Showing 1–50 of 317 results for author: Fazio, G

Detection and Evolution of Linear Polarization of the Galactic Center Transient MAXI J1744-294

Authors: Joseph M. Michail, Sebastiano D. von Fellenberg, Mayura Balakrishnan, Geoffrey C. Bower, Nicole M. Ford, Zach Sumners, Giovanni G. Fazio, Daryl Haggard, Joseph L. Hora, Garrett K. Keating, J. D. Livingston, Sera Markoff, Bart Ripperda, Sophia Sánchez-Maes, Howard A. Smith, S. P. Willner, Jun-Hui Zhao

Abstract: MAXI J1744$-$294, likely a low-mass X-ray binary system, is a Galactic-center transient source, detected at radio and X-ray wavelengths, located approximately $19''$ southeast of Sgr A*. We report the first detection of its variable linear polarization in four epochs spanning 2025 Apr 04--09. The normalized 33 and 43 GHz Stokes parameters $q$ and $u$ over the four epochs imply a common Faraday rot… ▽ More MAXI J1744$-$294, likely a low-mass X-ray binary system, is a Galactic-center transient source, detected at radio and X-ray wavelengths, located approximately $19''$ southeast of Sgr A*. We report the first detection of its variable linear polarization in four epochs spanning 2025 Apr 04--09. The normalized 33 and 43 GHz Stokes parameters $q$ and $u$ over the four epochs imply a common Faraday rotation screen with a rotation measure RM $=-63\,606^{+844}_{-861}$ radians m$^{-2}$, the third largest RM detected within the Galaxy. The RM is consistent with that of the Galactic center magnetar PSR J1745$-$2900, giving the first direct evidence that MAXI J1744 lies within the Galactic center region, is bound to Sgr A*, and therefore, is part of the nuclear star cluster. The uniformity in the Galactic center Faraday screen suggests that Sgr A*'s $\approx-10^5$ rad m$^{-2}$ RM is intrinsic rather than originating from an unrelated line-of-sight source. On 2025 Apr 06, we detected a secondary polarized component with an additional RM $\approx-6000$ rad m$^{-2}$, which was not seen at any other epoch. Assuming this secondary component primarily cools by synchrotron radiation, the implied local magnetic field strength is $\sim$15--30 gauss. In the context of a jetted X-ray binary progenitor, the additional RM screen and magnetic field strength are explainable with a short-lived knot in a putative jet. △ Less

Submitted 8 April, 2026; originally announced April 2026.

Comments: 15 pages, 6 figures, 4 tables, accepted to ApJ

An Agnostic Approach to Sustainability: From Capitals Substitutability to Non-Collapse Dynamics

Authors: Claudio Pirrone, Stefano Fricano, Gioacchino Fazio

Abstract: We construct a stochastic dynamical systems theory in which sustainability is a structural boundary property of a fully coupled Earth--Human--Production system. Each subsystem is modelled as a vector-valued process governed by stochastic differential equations with multiplicative noise and absolute bidirectional cross-subsystem flows. Biodiversity is endogenous, and societal evaluation is represen… ▽ More We construct a stochastic dynamical systems theory in which sustainability is a structural boundary property of a fully coupled Earth--Human--Production system. Each subsystem is modelled as a vector-valued process governed by stochastic differential equations with multiplicative noise and absolute bidirectional cross-subsystem flows. Biodiversity is endogenous, and societal evaluation is represented by a reflexive functional whose weights depend on evolving human capabilities. Sustainability, development, and sustainable development are defined as trajectory properties. Sustainability corresponds to boundary non-attainment with positive or unit probability; development corresponds to local ascent in the evaluation functional; sustainable development requires directional alignment under strictly positive survival probability. No optimisation problem is imposed. Necessary and sufficient conditions are derived using Feller boundary classification and stochastic Lyapunov methods. A central result identifies the sign of the net absolute cross-subsystem flow on each component as a phase-transition parameter: if negative near zero, the boundary is of exit type and almost-sure persistence is structurally impossible, independent of intrinsic regeneration, capability accumulation, or productivity parameters. Because flows are absolute, any perturbation diffuses through the entire coupled system without requiring correlated exogenous shocks. The reflexive evaluation structure generically induces non-transitive development relations, providing a formal mechanism for path-dependent welfare comparisons. Sustainability emerges as a geometric property of boundary structure and vector-field alignment, not as a corollary of intertemporal optimality. △ Less

Submitted 26 February, 2026; originally announced February 2026.

Photometric Constraints on Intermediate-mass Black Holes in the Galactic Centre

Authors: Tamojeet Roychowdhury, Sebastiano D. von Fellenberg, Joseph M. Michail, S. P. Willner, Nicole M. Ford, Zach Sumners, Sophia Sanchez-Maes, Tuan Do, Macarena Garcia Marin, Sera Markoff, Giovanni G. Fazio, Daryl Haggard, Joseph L. Hora, Bart Ripperda, Nadeen B. Sabha, Howard A. Smith, Gunther Witzel

Abstract: JWST/MIRI observations can place photometric limits on the presence of an intermediate-mass black hole (IMBH) near the Galactic Centre. The stellar complex IRS 13E, a co-moving conglomerate of young and massive stars, is a prime location to study because it has been speculated to be bound by an IMBH. Assuming a standard radiatively inefficient accretion flow (RIAF) and a minimum fractional variabi… ▽ More JWST/MIRI observations can place photometric limits on the presence of an intermediate-mass black hole (IMBH) near the Galactic Centre. The stellar complex IRS 13E, a co-moving conglomerate of young and massive stars, is a prime location to study because it has been speculated to be bound by an IMBH. Assuming a standard radiatively inefficient accretion flow (RIAF) and a minimum fractional variability of 10% of intrinsic luminosity, the wavelength of peak emission in the spectral energy distribution for an IMBH would lie in the mid-infrared ($\sim$ 5-25 $μ$m), and variability would be detectable in MIRI time-series observations. Monitoring fails to detect such variable emission (other than from Sgr A*) in and around the IRS 13E complex, and upper limits on a putative IMBH's intrinsic variability on timescales of minutes to about 1 hour are $\lesssim$1 mJy at 12 $μ$m and $\lesssim$2 mJy at 19 $μ$m. These translate to luminosities $\lesssim 25 \times 10^{32}$ erg/s. The resulting limits on the IMBH mass and accretion rate rule out any IMBH with mass $\gtrsim 10^3$ M$_\odot$ accreting at $\gtrsim 10^{-6}$ times Eddington rate at the location of IRS 13E. Further, the observations rule out an IMBH anywhere in the central 6" $\times$ 6" region that is more massive than $\approx$ 2 $\times 10^3$ M$_\odot$ and accreting at $\gtrsim 10^{-6}$ of the Eddington rate. Assuming Bondi accretion scaled to typical RIAF-accretion efficiencies, albeit somewhat uncertain, also allows us to rule out IMBHs moving with typical velocities of about 200 km/s and masses $\gtrsim 2 \times 10^3$ M$_\odot$. These methods showcase the effectiveness of photometric variability measurements in constraining the presence of accreting black holes in Galactic centre-like environments. △ Less

Submitted 18 November, 2025; originally announced November 2025.

Comments: 14 pages, 4 figures, accepted in Publications of Astronomical Society of the Pacific. Corresponding references for extinction correction (von Fellenberg et al.) and aperture correction (Michail et al.) also posted to arXiv today

Journal ref: Publications of the Astronomical Society of the Pacific 2025, Volume 137, Number 11

Mid-infrared extinction toward the Galactic center

Authors: Sebastiano D. von Fellenberg, Joseph M. Michail, S. P. Willner, Braden Seefeldt-Gail, Tamojeet Roychowdhury, Macarena Garcia Marin, Giovanni G. Fazio, Nicole M. Ford, Daryl Haggard, Joseph L. Hora, Howard A. Smith, Zach Sumners, Gunther Witzel

Abstract: We determine the mid-infrared (MIR, $\sim$5~μm--22~μm) extinction towards the Galactic center using MIRI/MRS integral field unit (IFU) observations of the central $3''\times3''$ region (near 5~μm) to $7''\times7''$ region (near 22~μm). To measure the MIR extinction, we employ two approaches: modeling the intrinsic-to-observed dust thermal spectrum and assessing the differential extinction between… ▽ More We determine the mid-infrared (MIR, $\sim$5~μm--22~μm) extinction towards the Galactic center using MIRI/MRS integral field unit (IFU) observations of the central $3''\times3''$ region (near 5~μm) to $7''\times7''$ region (near 22~μm). To measure the MIR extinction, we employ two approaches: modeling the intrinsic-to-observed dust thermal spectrum and assessing the differential extinction between hydrogen recombination lines. Expanding on prior work, we directly model the dust-opacity distribution along the line of sight, and we make available a Python code that provides a flexible tool for deriving intrinsic dust emission spectra. We confirm the spatial variability of extinction across the field, demonstrating that dusty sources--such as IRS~29N--exhibit higher local extinction. Furthermore, we verify the absence of PAH emission features in the Galactic center MIR spectra. Using the two complementary methods, we derive a refined ``best guess'' MIR extinction law for Sgr A* and the surrounding Galactic-center region. By applying the extinction law to a MIR flare measurement discussed in a companion paper Michail et al. 2025, we estimate a residual relative extinction uncertainty for the short MIRI/MRS grating on the order of $0.2~\mathrm{mag}$ {from $\sim$5 to $\sim$18~μm\ and $\sim$0.3~mag from $\sim$18 to $\sim$22~μm}, consistent with our uncertainty estimate. △ Less

Submitted 18 November, 2025; originally announced November 2025.

Comments: Accepted for publications in ApJ, Sgr A* SED companion paper posted to arXiv today (Michail et al.) and extinction correction results are used in IMBH constraint paper (Roychowdhury et al., 2025, PASP) also posted to arXiv today

First Mid-infrared Detection and Modeling of a Flare from Sgr A*. II. Mid-IR Spectral Energy Distribution and Millimeter Polarimetry

Authors: Joseph M. Michail, Sebastiano D. von Fellenberg, Garrett K. Keating, Ramprasad Rao, Tamojeet Roychowdhury, S. P. Willner, Nicole M. Ford, Daryl Haggard, Sera Markoff, Alexander Philippov, Bart Ripperda, Sophia Sánchez-Maes, Zach Sumners, Gunther Witzel, Mayura Balakrishnan, Sunil Chandra, Kazuhiro Hada, Macarena Garcia Marin, Mark A. Gurwell, Giovanni G. Fazio, Joseph L. Hora, Braden Seefeldt-Gail, Howard A. Smith

Abstract: S. D. von Fellenberg et al. (2025a, Paper I) reported the first mid-infrared detection of a flare from Sgr A*. The JWST/MIRI/MRS observations were consistent with an orbiting hotspot undergoing electron injection with a spectrum that subsequently breaks from synchrotron cooling. However, mid-infrared extinction measurements appropriate for these data were not yet determined, and therefore the temp… ▽ More S. D. von Fellenberg et al. (2025a, Paper I) reported the first mid-infrared detection of a flare from Sgr A*. The JWST/MIRI/MRS observations were consistent with an orbiting hotspot undergoing electron injection with a spectrum that subsequently breaks from synchrotron cooling. However, mid-infrared extinction measurements appropriate for these data were not yet determined, and therefore the temporal evolution of the absolute spectral index remained unknown. This work applies new Galactic Center extinction measurements to the flare observations. The evolution of the spectral index after the peak is fully consistent with that reported in Paper I with a maximum absolute mid-infrared spectral index $α_{\rm{MIR}}=0.45\pm0.01_{\rm{stat}}\pm0.08_{\rm{sys}}$ during the second mid-infrared flare peak, matching the known near-infrared spectral index during bright states ($α_{\rm{NIR}}\approx0.5$). There was a near-instantaneous change in the mid-infrared spectral index of $Δα_{\rm{MIR}}=0.33\pm0.06_{\rm{stat}}\pm0.11_{\rm{sys}}$ at the flare onset. We propose this as a quantitative definition for this infrared flare's beginning, physically interpreted as the underlying electron distribution's transition into a hard power-law distribution. This paper also reports the SMA millimeter polarization during the flare, which shows a small, distorted, but overall clockwise-oriented Stokes Q--U loop during the third mid-infrared peak. Extrapolating the mid-infrared flux power law to the millimeter yields a variable flux consistent with the observed 220 GHz emission. These results, together with the Paper I modeling, plausibly suggest a single hotspot produced both the mid-infrared and millimeter variability during this event. However, additional flares are required to make a general statement about the millimeter and mid-infrared connection. △ Less

Submitted 18 November, 2025; originally announced November 2025.

Comments: 20 pages, 8 figures, submitted to ApJ; revised version posted after minor referee comments addressed. Extinction companion paper posted to arXiv today (von Fellenberg et al.) and aperture correction results are used in IMBH constraint paper (Roychowdhury et al., 2025, PASP) also posted to arXiv today

Quantifying Systemic Vulnerability in the Foundation Model Industry

Authors: Claudio Pirrone, Stefano Fricano, Gioacchino Fazio

Abstract: The foundation model industry exhibits unprecedented concentration in critical inputs: semiconductors, energy infrastructure, elite talent, capital, and training data. Despite extensive sectoral analyses, no comprehensive framework exists for assessing overall industrial vulnerability. We develop the Artificial Intelligence Industrial Vulnerability Index (AIIVI) grounded in O-Ring production theor… ▽ More The foundation model industry exhibits unprecedented concentration in critical inputs: semiconductors, energy infrastructure, elite talent, capital, and training data. Despite extensive sectoral analyses, no comprehensive framework exists for assessing overall industrial vulnerability. We develop the Artificial Intelligence Industrial Vulnerability Index (AIIVI) grounded in O-Ring production theory, recognizing that foundation model production requires simultaneous availability of non-substitutable inputs. Given extreme data opacity and rapid technological evolution, we implement a validated human-in-the-loop methodology using large language models to systematically extract indicators from dispersed grey literature, with complete human verification of all outputs. Applied to six state-of-the-art foundation model developers, AIIVI equals 0.82, indicating extreme vulnerability driven by compute infrastructure (0.85) and energy systems (0.90). While industrial policy currently emphasizes semiconductor capacity, energy infrastructure represents the emerging binding constraint. This methodology proves applicable to other fast-evolving, opaque industries where traditional data sources are inadequate. △ Less

Submitted 24 March, 2026; v1 submitted 27 October, 2025; originally announced October 2025.

Comments: Conference Paper - SIEPI (29-30 January 2026) - Bari

Weight-dependent and weight-independent measures of quantum incompatibility in multiparameter estimation

Authors: Jiayu He, Gabriele Fazio, Matteo G. A. Paris

Abstract: Multiparameter quantum estimation faces a fundamental challenge due to the inherent incompatibility of optimal measurements for different parameters, a direct consequence of quantum non-commutativity. This incompatibility is quantified by the gap between the symmetric logarithmic derivative (SLD) quantum Cramér-Rao bound, which is not always attainable, and the asymptotically achievable Holevo bou… ▽ More Multiparameter quantum estimation faces a fundamental challenge due to the inherent incompatibility of optimal measurements for different parameters, a direct consequence of quantum non-commutativity. This incompatibility is quantified by the gap between the symmetric logarithmic derivative (SLD) quantum Cramér-Rao bound, which is not always attainable, and the asymptotically achievable Holevo bound. This work provides a comprehensive analysis of this gap by introducing and contrasting two scalar measures. The first is the weight-independent quantumness measure $R$, which captures the intrinsic incompatibility of the estimation model. The second is a tighter, weight-dependent measure $T[W]$ which explicitly incorporates the cost matrix $W$ assigning relative importance to different parameters. We establish a hierarchy of bounds based on these two measures and derive necessary and sufficient conditions for their saturation. Through analytical and numerical studies of tunable qubit and qutrit models with SU(2) unitary encoding, we demonstrate that the weight-dependent bound $C_{T}[W]$ often provides a significantly tighter approximation to the Holevo bound $C_{H}[W]$ than the $R$-dependent bound, especially in higher-dimensional systems. We also develop an approach based on $C_{T}[W]$ to compute the Holevo bound $C_{H}[W]$ analytically. Our results highlight the critical role of the weight matrix's structure in determining the precision limits of multiparameter quantum metrology. △ Less

Submitted 21 October, 2025; originally announced October 2025.

Orders matter: tight bounds on the precision of sequential quantum estimation for multiparameter models

Authors: Gabriele Fazio, Jiayu He, Matteo G. A. Paris

Abstract: In multiparameter quantum metrology, the ultimate precision of joint estimation is dictated by the Holevo Cramér-Rao bound. In this paper, we discuss and analyze in detail an alternative approach: the stepwise estimation strategy. In this approach, parameters are estimated sequentially, using an optimized fraction of the total available resources allocated to each step. We derive a tight and achie… ▽ More In multiparameter quantum metrology, the ultimate precision of joint estimation is dictated by the Holevo Cramér-Rao bound. In this paper, we discuss and analyze in detail an alternative approach: the stepwise estimation strategy. In this approach, parameters are estimated sequentially, using an optimized fraction of the total available resources allocated to each step. We derive a tight and achievable precision bound for this protocol, the stepwise separable bound, and provide its closed-form analytical expression, revealing a crucial dependence on the chosen measurement ordering. We provide a rigorous comparison with the joint measurement strategy, deriving analytical conditions that determine when the stepwise approach offers superior precision. Through the analysis of several paradigmatic SU(2) unitary encoding models, we demonstrate that the stepwise strategy can indeed outperform joint measurements, particularly in scenarios characterized by non-optimal probes or models with a high degree of sloppiness. Our findings establish stepwise estimation as a powerful alternative to joint and collective measurements, proving that sequential protocols can provide a genuine metrological advantage, especially in resource-constrained or imperfect experimental settings. △ Less

Submitted 22 October, 2025; v1 submitted 16 October, 2025; originally announced October 2025.

Comments: 26 pages, 1 figure

Higher Hölder regularity for degenerate elliptic PDEs with data in Morrey spaces

Authors: Giuseppe Di Fazio, Rafayel Teymurazyan, José Miguel Urbano

Abstract: We establish sharp local $C^{1,α}$-regularity for weak solutions to degenerate elliptic equations of $p$-Laplacian type with data in Morrey spaces. The proof relies on the Fefferman-Phong inequality and standard tools from regularity theory for nonlinear PDEs. We establish sharp local $C^{1,α}$-regularity for weak solutions to degenerate elliptic equations of $p$-Laplacian type with data in Morrey spaces. The proof relies on the Fefferman-Phong inequality and standard tools from regularity theory for nonlinear PDEs. △ Less

Submitted 11 October, 2025; originally announced October 2025.

Comments: 12 pages

MSC Class: 35B65; 35J70; 35J92

PEARLS: 21 Transients Found in the Three-Epoch NIRCam Observations in the Continuous Viewing Zone of the James Webb Space Telescope

Authors: Haojing Yan, Bangzheng Sun, Zhiyuan Ma, Lifan Wang, Christopher N. A. Willmer, Wenlei Chen, Norman A. Grogin, John F. Beacom, S. P. Willner, Seth H. Cohen, Rogier A. Windhorst, Rolf A. Jansen, Cheng Cheng, Jia-Sheng Huang, Min Yun, Hansung B. Gim, Heidi B. Hammel, Stefanie N. Milam, Anton M. Koekemoer, Lei Hu, Jose M. Diego, Jake Summers, Jordan C. J. D'Silva, Dan Coe, Christopher J. Conselice , et al. (17 additional authors not shown)

Abstract: We present 21 transients from our three-epoch, four-band NIRCam observations covering 14.16 arcmin^2 in the Spitzer IRAC Dark Field (IDF), taken by the JWST Prime Extragalactic Areas for Reionization and Lensing Science program with a time cadence of ~6 months. A separate Hubble Space Telescope program provided Advanced Camera for Surveys optical imaging contemporaneous with the second and third e… ▽ More We present 21 transients from our three-epoch, four-band NIRCam observations covering 14.16 arcmin^2 in the Spitzer IRAC Dark Field (IDF), taken by the JWST Prime Extragalactic Areas for Reionization and Lensing Science program with a time cadence of ~6 months. A separate Hubble Space Telescope program provided Advanced Camera for Surveys optical imaging contemporaneous with the second and third epochs of the NIRCam observations. The NIRSpec spectroscopy on three transients confirmed a Type Ia supernova at z=1.63 and the host galaxies of the other two at z=2.64 and 1.90, respectively. Combining these with the photometric redshifts (z_ph) of the host galaxies in the rest of the sample, we find that the transients are in either a "mid-z" group at z>1.6 with M_V < -16.0 mag or a "low-z" group at z < 0.4 with M_H > -14.0 mag. The mid-z transients are consistent with supernovae. In contrast, the low-z transients' luminosities fall in the range of the so-called "gap transients" between supernovae and novae. However, this latter conclusion is only tentative due to possible catastrophic failures in z_ph that could bias them to low-z. Conversely, if they are indeed at z < 0.4, it would be worth studying similar transients in the future. Our work further demonstrates the power of NIRCam in transient science and also shows that it would be more fruitful to carry out a long-term monitoring program with more passbands, a higher cadence and prompt follw-up spectroscopy. Being in the continuous viewing zone of the JWST, the IDF is an ideal field for this purpose. △ Less

Submitted 10 January, 2026; v1 submitted 13 June, 2025; originally announced June 2025.

Comments: Accepted (on December 9, 2025) for publication in ApJ. Revisions made to match the published version

JWST's PEARLS: A z=6 quasar in a train-wreck galaxy merger system

Authors: Madeline A. Marshall, Rogier A. Windhorst, Giovanni Ferrami, S. P. Willner, Maria Polletta, William C. Keel, Giovanni G. Fazio, Seth H. Cohen, Timothy Carleton, Rolf A. Jansen, Rachel Honor, Rafael Ortiz III, Jake Summers, Jordan C. J. D'Silva, Anton M. Koekemoer, Dan Coe, Christopher J. Conselice, Jose M. Diego, Simon P. Driver, Brenda Frye, Norman A. Grogin, Nor Pirzkal, Aaron Robotham, Russell E. Ryan, Jr., Christopher N. A. Willmer , et al. (13 additional authors not shown)

Abstract: We present JWST NIRSpec integral field spectroscopy observations of the z=5.89 quasar NDWFS J1425+3254 from 0.6-5.3 microns, covering the rest-frame ultraviolet and optical at a spectral resolution of R~100. The quasar has a black hole mass of $M_{\rm{BH}}=(1.4\substack{+3.1\\-1.0})\times10^9 M_\odot$ and an Eddington ratio of $L_{\rm{Bol}}/L_{\rm{Edd}}=0.3\substack{+0.6\\-0.2}$, as implied from t… ▽ More We present JWST NIRSpec integral field spectroscopy observations of the z=5.89 quasar NDWFS J1425+3254 from 0.6-5.3 microns, covering the rest-frame ultraviolet and optical at a spectral resolution of R~100. The quasar has a black hole mass of $M_{\rm{BH}}=(1.4\substack{+3.1\\-1.0})\times10^9 M_\odot$ and an Eddington ratio of $L_{\rm{Bol}}/L_{\rm{Edd}}=0.3\substack{+0.6\\-0.2}$, as implied from the broad Balmer H$α$ and H$β$ lines. The quasar host has significant ongoing obscured star formation, as well as a quasar-driven outflow with velocity $6050\substack{+460\\-630}$ km/s and ionised outflow rate of $1650\substack{+130\\-1230}M_\odot$yr$^{-1}$. This is possibly one of the most extreme outflows in the early Universe. The data also reveal that two companion galaxies are merging with the quasar host. The north-eastern companion galaxy is relatively old and very massive, with a luminosity-weighted stellar age of $65\substack{+9\\-4}$ Myr, stellar mass of $(3.6\substack{+0.6\\-0.3})\times10^{11} M_\odot$, and star-formation rate (SFR) of ~15-30 $M_\odot$yr$^{-1}$. A bridge of gas connects this companion galaxy and the host, confirming their ongoing interaction. A second merger is occurring between the quasar host and a much younger companion galaxy to the south, with a stellar age of $6.7\pm1.8$ Myr, stellar mass of $(1.9\pm0.4)\times10^{10} M_\odot$, and SFR of ~40-65 $M_\odot$yr$^{-1}$. There is also another galaxy in the field, likely in the foreground at z=1.135, which could be gravitationally lensing the quasar with magnification $1<μ<2$, and, thus, <0.75 mag. Overall, the system is a 'train-wreck' merger of three galaxies, with star formation and extreme quasar activity that were likely triggered by these ongoing interactions. △ Less

Submitted 3 September, 2025; v1 submitted 27 February, 2025; originally announced February 2025.

Comments: Accepted for publication in A&A

Journal ref: A&A 702, A174 (2025)

Cartan Quantum Metrology

Authors: Gabriele Fazio, Jiayu He, Matteo G. A. Paris

Abstract: We address the characterization of two-qubit gates, focusing on bounds to precision in the joint estimation of the three parameters that define their Cartan decomposition. We derive the optimal probe states that jointly maximize precision, minimize sloppiness, and eliminate quantum incompatibility. Additionally, we analyze the properties of the set of optimal probes and evaluate their robustness a… ▽ More We address the characterization of two-qubit gates, focusing on bounds to precision in the joint estimation of the three parameters that define their Cartan decomposition. We derive the optimal probe states that jointly maximize precision, minimize sloppiness, and eliminate quantum incompatibility. Additionally, we analyze the properties of the set of optimal probes and evaluate their robustness against noise. △ Less

Submitted 12 February, 2025; originally announced February 2025.

Comments: 17 pages, 8 figures

First mid-infrared detection and modeling of a flare from Sgr A*

Authors: Sebastiano D. von Fellenberg, Tamojeet Roychowdhury, Joseph M. Michail, Zach Sumners, Grace Sanger-Johnson, Giovanni G. Fazio, Daryl Haggard, Joseph L. Hora, Alexander Philippov, Bart Ripperda, Howard A. Smith, S. P. Willner, Gunther Witzel, Shuo Zhang, Eric E. Becklin, Geoffrey C. Bower, Sunil Chandra, Tuan Do, Macarena Garcia Marin, Mark A. Gurwell, Nicole M. Ford, Kazuhiro Hada, Sera Markoff, Mark R. Morris, Joey Neilsen , et al. (2 additional authors not shown)

Abstract: The time-variable emission from the accretion flow of Sgr A*, the supermassive black hole at the Galactic Center, has long been examined in the radio-to-mm, near-infrared (NIR), and X-ray regimes of the electromagnetic spectrum. However, until now, sensitivity and angular resolution have been insufficient in the crucial mid-infrared (MIR) regime. The MIRI instrument on JWST has changed that, and w… ▽ More The time-variable emission from the accretion flow of Sgr A*, the supermassive black hole at the Galactic Center, has long been examined in the radio-to-mm, near-infrared (NIR), and X-ray regimes of the electromagnetic spectrum. However, until now, sensitivity and angular resolution have been insufficient in the crucial mid-infrared (MIR) regime. The MIRI instrument on JWST has changed that, and we report the first MIR detection of Sgr A*. The detection was during a flare that lasted about 40 minutes, a duration similar to NIR and X-ray flares, and the source's spectral index steepened as the flare ended. The steepening suggests synchrotron cooling is an important process for Sgr A*'s variability and implies magnetic field strengths $\sim$40--70 Gauss in the emission zone. Observations at $1.3~\mathrm{mm}$ with the Submillimeter Array revealed a counterpart flare lagging the MIR flare by $\approx$10 minutes. The observations can be self-consistently explained as synchrotron radiation from a single population of gradually cooling high-energy electrons accelerated through (a combination of) magnetic reconnection and/or magnetized turbulence. △ Less

Submitted 13 January, 2025; originally announced January 2025.

Comments: Accepted for publication ApJL

Regularity for Weak Solutions to First-Order Local Mean Field Games

Authors: Abdulrahman Alharbi, Diogo Gomes, Giuseppe Di Fazio, Melih Ucer

Abstract: We establish interior regularity results for first-order, stationary, local mean-field game (MFG) systems. Specifically, we study solutions of the coupled system consisting of a Hamilton-Jacobi-Bellman equation $H(x, Du, m) = 0$ and a transport equation $-\operatorname{div}(m D_pH(x, Du, m)) = 0$ in a domain $Ω\subset \mathbb{R}^d$. Under suitable structural assumptions on the Hamiltonian $H$, wit… ▽ More We establish interior regularity results for first-order, stationary, local mean-field game (MFG) systems. Specifically, we study solutions of the coupled system consisting of a Hamilton-Jacobi-Bellman equation $H(x, Du, m) = 0$ and a transport equation $-\operatorname{div}(m D_pH(x, Du, m)) = 0$ in a domain $Ω\subset \mathbb{R}^d$. Under suitable structural assumptions on the Hamiltonian $H$, without requiring monotonicity of the system, convexity of the Hamiltonian, separability in variables, or smoothness beyond basic continuity in $(p,m)$, we introduce a notion of weak solutions that allows the application of techniques from elliptic regularity theory. Our main contribution is to prove that the value function $u$ is locally Hölder continuous in $Ω$. The proof leverages the connection between first-order MFG systems and quasilinear equations in divergence form, adapting classical techniques to handle the specific structure of MFG systems. △ Less

Submitted 2 June, 2025; v1 submitted 17 November, 2024; originally announced November 2024.

Comments: 25 pages

MSC Class: 35Q89 (Primary) 35B65 (Secondary)

Journal ref: Nonlinear Differential Equations and Applications, 2025

Evolutionary Game Dynamics Applied to Strategic Adoption of Immersive Technologies in Cultural Heritage and Tourism

Authors: Gioacchino Fazio, Stefano Fricano, Claudio Pirrone

Abstract: Immersive technologies such as Metaverse, AR, and VR are at a crossroads, with many actors pondering their adoption and potential sectors interested in integration. The cultural and tourism industries are particularly impacted, facing significant pressure to make decisions that could shape their future landscapes. Stakeholders' perceptions play a crucial role in this process, influencing the speed… ▽ More Immersive technologies such as Metaverse, AR, and VR are at a crossroads, with many actors pondering their adoption and potential sectors interested in integration. The cultural and tourism industries are particularly impacted, facing significant pressure to make decisions that could shape their future landscapes. Stakeholders' perceptions play a crucial role in this process, influencing the speed and extent of technology adoption. As immersive technologies promise to revolutionize experiences, stakeholders in these fields weigh the benefits and challenges of embracing such innovations. The current choices will likely determine the trajectory of cultural preservation and tourism enhancement, potentially transforming how we engage with history, art, and travel. Starting from a decomposition of stakeholders' perceptions into principal components using Q-methodology, this article employs an evolutionary game model to attempt to map possible scenarios and highlight potential decision-making trajectories. The proposed approach highlights how evolutionary dynamics lead to identifying a dominant long-term strategy that emerges from the complex system of coexistence among various stakeholders. △ Less

Submitted 26 August, 2024; originally announced September 2024.

General Relativistic effects and the NIR variability of Sgr A* II: A systematic approach to temporal asymmetry

Authors: Sebastiano D. von Fellenberg, Gunther Witzel, Michi Bauboeck, Hui-Hsuan Chung, Nicola Marchili, Greg Martinez, Matteo Sadun-Bordoni, Guillaume Bourdarot, Tuan Do, Antonia Drescher, Giovanni Fazio, Frank Eisenhauer, Reinhard Genzel, Stefan Gillessen, Joseph L. Hora, Felix Mang, Thomas Ott, Howard A. Smith, Eduardo Ros, Diogo C. Ribeiro, Felix Widmann, S. P. Willner, J. Anton Zensus

Abstract: A systematic study, based on the third-moment structure function, of Sgr A*'s variability finds an exponential rise time $τ_{1,\rm{obs}}=14.8^{+0.4}_{-1.5}~\mathrm{minutes}$ and decay time $τ_{2,\rm{obs}}=13.1^{+1.3}_{-1.4}~\mathrm{minutes}$. This symmetry of the flux-density variability is consistent with earlier work, and we interpret it as caused by the dominance of Doppler boosting, as opposed… ▽ More A systematic study, based on the third-moment structure function, of Sgr A*'s variability finds an exponential rise time $τ_{1,\rm{obs}}=14.8^{+0.4}_{-1.5}~\mathrm{minutes}$ and decay time $τ_{2,\rm{obs}}=13.1^{+1.3}_{-1.4}~\mathrm{minutes}$. This symmetry of the flux-density variability is consistent with earlier work, and we interpret it as caused by the dominance of Doppler boosting, as opposed to gravitational lensing, in Sgr~A*'s light curve. A relativistic, semi-physical model of Sgr~A* confirms an inclination angle $i<45$ degrees. The model also shows that the emission of the intrinsic radiative process can have some asymmetry even though the observed emission does not. The third-moment structure function, which is a measure of the skewness of the light-curve increments, may be a useful summary statistic in other contexts of astronomy because it senses only temporal asymmetry, i.e., it averages to zero for any temporally symmetric signal. △ Less

Submitted 9 July, 2024; originally announced July 2024.

Comments: Accepted for publication in A&A letters

Journal ref: A&A 688, L12 (2024)

Multiwavelength Observations of Sgr A*. II. 2019 July 21 and 26

Authors: Joseph M. Michail, Farhad Yusef-Zadeh, Mark Wardle, Devaky Kunneriath, Joseph L. Hora, Howard Bushouse, Giovanni G. Fazio, Sera Markoff, Howard A. Smith

Abstract: We report on the final two days of a multiwavelength campaign of Sgr A* observing in the radio, submillimeter, infrared, and X-ray bands in July 2019. Sgr A* was remarkably active, showing multiple flaring events across the electromagnetic spectrum. We detect a transient $\sim35$-minute periodicity feature in Spitzer Space Telescope light curves on 21 July 2019. Time-delayed emission was detected… ▽ More We report on the final two days of a multiwavelength campaign of Sgr A* observing in the radio, submillimeter, infrared, and X-ray bands in July 2019. Sgr A* was remarkably active, showing multiple flaring events across the electromagnetic spectrum. We detect a transient $\sim35$-minute periodicity feature in Spitzer Space Telescope light curves on 21 July 2019. Time-delayed emission was detected in ALMA light curves, suggesting a hotspot within the accretion flow on a stable orbit. On the same night, we observe a decreased flux in the submillimeter light curve following an X-ray flare detected by the Chandra X-ray Observatory and model the feature with an adiabatically expanding synchrotron hotspot occulting the accretion flow. The event is produced by a plasma $0.55~R_{\text{S}}$ in radius with an electron spectrum $p=2.84$. It is threaded by a $\sim130$ Gauss magnetic field and expands at $0.6\%$ the speed of light. Finally, we reveal an unambiguous flare in the infrared, submillimeter, and radio, demonstrating that the variable emission is intrinsically linked. We jointly fit the radio and submillimeter light curves using an adiabatically expanding synchrotron hotspot and find it is produced by a plasma with an electron spectrum $p=0.59$, $187$ Gauss magnetic field, and radius $0.47~R_{\text{S}}$ that expands at $0.029c$. In both cases, the uncertainty in the appropriate lower and upper electron energy bounds may inflate the derived equipartition field strengths by a factor of 2 or more. Our results confirm that both synchrotron- and adiabatic-cooling processes are involved in the variable emission's evolution at submillimeter and infrared wavelengths. △ Less

Submitted 3 June, 2024; originally announced June 2024.

Comments: 24 pages, 13 figures, accepted to The Astrophysical Journal. Comments welcome! Paper I can be found here: arXiv:2107.09681

TREASUREHUNT: Transients and Variability Discovered with HST in the JWST North Ecliptic Pole Time Domain Field

Authors: Rosalia O'Brien, Rolf A. Jansen, Norman A. Grogin, Seth H. Cohen, Brent M. Smith, Ross M. Silver, W. P. Maksym III, Rogier A. Windhorst, Timothy Carleton, Anton M. Koekemoer, Nimish P. Hathi, Christopher N. A. Willmer, Brenda L. Frye, M. Alpaslan, M. L. N. Ashby, T. A. Ashcraft, S. Bonoli, W. Brisken, N. Cappelluti, F. Civano, C. J. Conselice, V. S. Dhillon, S. P. Driver, K. J. Duncan, R. Dupke , et al. (34 additional authors not shown)

Abstract: The JWST North Ecliptic Pole (NEP) Time Domain Field (TDF) is a $>$14 arcmin diameter field optimized for multi-wavelength time-domain science with JWST. It has been observed across the electromagnetic spectrum both from the ground and from space, including with the Hubble Space Telescope (HST). As part of HST observations over 3 cycles (the "TREASUREHUNT" program), deep images were obtained with… ▽ More The JWST North Ecliptic Pole (NEP) Time Domain Field (TDF) is a $>$14 arcmin diameter field optimized for multi-wavelength time-domain science with JWST. It has been observed across the electromagnetic spectrum both from the ground and from space, including with the Hubble Space Telescope (HST). As part of HST observations over 3 cycles (the "TREASUREHUNT" program), deep images were obtained with ACS/WFC in F435W and F606W that cover almost the entire JWST NEP TDF. Many of the individual pointings of these programs partially overlap, allowing an initial assessment of the potential of this field for time-domain science with HST and JWST. The cumulative area of overlapping pointings is ~88 arcmin$^2$, with time intervals between individual epochs that range between 1 day and 4$+$ years. To a depth of $m_{AB}$ $\simeq$ 29.5 mag (F606W), we present the discovery of 12 transients and 190 variable candidates. For the variable candidates, we demonstrate that Gaussian statistics are applicable, and estimate that ~80 are false positives. The majority of the transients will be supernovae, although at least two are likely quasars. Most variable candidates are AGN, where we find 0.42% of the general $z$ $<$ 6 field galaxy population to vary at the $~3σ$ level. Based on a 5-year timeframe, this translates into a random supernova areal density of up to ~0.07 transients per arcmin$^2$ (~245 deg$^{-2}$) per epoch, and a variable AGN areal density of ~1.25 variables per arcmin$^2$ (~4500 deg$^{-2}$) to these depths. △ Less

Submitted 2 May, 2024; v1 submitted 10 January, 2024; originally announced January 2024.

Comments: 32 pages, 11 figures, 5 tables, 1 Appendix

$C^{1,α}$ Regularity For Stationary Mean-Field Games With Logarithmic Coupling

Authors: Tigran Bakaryan, Giuseppe Di Fazio, Diogo A. Gomes

Abstract: This paper investigates stationary mean-field games (MFGs) on the torus with Lipschitz non-homogeneous diffusion and logarithmic-like couplings. The primary objective is to understand the existence of $C^{1,α}$ solutions to address the research gap between low-regularity results for bounded and measurable diffusions and the smooth results modeled by the Laplacian. We use the Hopf--Cole transform… ▽ More This paper investigates stationary mean-field games (MFGs) on the torus with Lipschitz non-homogeneous diffusion and logarithmic-like couplings. The primary objective is to understand the existence of $C^{1,α}$ solutions to address the research gap between low-regularity results for bounded and measurable diffusions and the smooth results modeled by the Laplacian. We use the Hopf--Cole transformation to convert the MFG system into a scalar elliptic equation. Then, we apply Morrey space methods to establish the existence and regularity of solutions. The introduction of Morrey space methods offers a novel approach to address regularity issues in the context of MFGs. △ Less

Submitted 25 October, 2023; originally announced October 2023.

Comments: 26 pages

MSC Class: 35J4; 35A0; 91A16;

Hidden giants in JWST's PEARLS: An ultra-massive z=4.26 sub-millimeter galaxy that is invisible to HST

Authors: Ian Smail, Ugne Dudzeviciute, Mark Gurwell, Giovanni G. Fazio, S. P. Willner, A. M. Swinbank, Vinodiran Arumugam, Jake Summers, Seth H. Cohen, Rolf A. Jansen, Rogier A. Windhorst, Ashish Meena, Adi Zitrin, William C. Keel, Dan Coe, Christopher J. Conselice, Jordan C. J. D'Silva, Simon P. Driver, Brenda Frye, Norman A. Grogin, Anton M. Koekemoer, Madeline A. Marshall, Mario Nonino, Nor Pirzkal, Aaron Robotham , et al. (10 additional authors not shown)

Abstract: We present a multi-wavelength analysis using SMA, JCMT, NOEMA, JWST, HST, and SST of two dusty strongly star-forming galaxies, 850.1 and 850.2, seen through the massive cluster lens A1489. These SMA-located sources both lie at z=4.26 and have bright dust continuum emission, but 850.2 is a UV-detected Lyman-break galaxy, while 850.1 is undetected at <2um, even with deep JWST/NIRCam observations. We… ▽ More We present a multi-wavelength analysis using SMA, JCMT, NOEMA, JWST, HST, and SST of two dusty strongly star-forming galaxies, 850.1 and 850.2, seen through the massive cluster lens A1489. These SMA-located sources both lie at z=4.26 and have bright dust continuum emission, but 850.2 is a UV-detected Lyman-break galaxy, while 850.1 is undetected at <2um, even with deep JWST/NIRCam observations. We investigate their stellar, ISM, and dynamical properties, including a pixel-level SED analysis to derive sub-kpc-resolution stellar-mass and Av maps. We find that 850.1 is one of the most massive and highly obscured, Av~5, galaxies known at z>4 with M*~10^11.8 Mo (likely forming at z>6), and 850.2 is one of the least massive and least obscured, Av~1, members of the z>4 dusty star-forming population. The diversity of these two dust-mass-selected galaxies illustrates the incompleteness of galaxy surveys at z>3-4 based on imaging at <2um, the longest wavelengths feasible from HST or the ground. The resolved mass map of 850.1 shows a compact stellar mass distribution, Re(mass)~1kpc, but its expected evolution to z~1.5 and then z~0 matches both the properties of massive, quiescent galaxies at z~1.5 and ultra-massive early-type galaxies at z~0. We suggest that 850.1 is the central galaxy of a group in which 850.2 is a satellite that will likely merge in the near future. The stellar morphology of 850.1 shows arms and a linear bar feature which we link to the active dynamical environment it resides within. △ Less

Submitted 28 June, 2023; originally announced June 2023.

Comments: Submitted to ApJ, comments welcome!

NANCY: Next-generation All-sky Near-infrared Community surveY

Authors: Jiwon Jesse Han, Arjun Dey, Adrian M. Price-Whelan, Joan Najita, Edward F. Schlafly, Andrew Saydjari, Risa H. Wechsler, Ana Bonaca, David J Schlegel, Charlie Conroy, Anand Raichoor, Alex Drlica-Wagner, Juna A. Kollmeier, Sergey E. Koposov, Gurtina Besla, Hans-Walter Rix, Alyssa Goodman, Douglas Finkbeiner, Abhijeet Anand, Matthew Ashby, Benedict Bahr-Kalus, Rachel Beaton, Jayashree Behera, Eric F. Bell, Eric C Bellm , et al. (184 additional authors not shown)

Abstract: The Nancy Grace Roman Space Telescope is capable of delivering an unprecedented all-sky, high-spatial resolution, multi-epoch infrared map to the astronomical community. This opportunity arises in the midst of numerous ground- and space-based surveys that will provide extensive spectroscopy and imaging together covering the entire sky (such as Rubin/LSST, Euclid, UNIONS, SPHEREx, DESI, SDSS-V, GAL… ▽ More The Nancy Grace Roman Space Telescope is capable of delivering an unprecedented all-sky, high-spatial resolution, multi-epoch infrared map to the astronomical community. This opportunity arises in the midst of numerous ground- and space-based surveys that will provide extensive spectroscopy and imaging together covering the entire sky (such as Rubin/LSST, Euclid, UNIONS, SPHEREx, DESI, SDSS-V, GALAH, 4MOST, WEAVE, MOONS, PFS, UVEX, NEO Surveyor, etc.). Roman can uniquely provide uniform high-spatial-resolution (~0.1 arcsec) imaging over the entire sky, vastly expanding the science reach and precision of all of these near-term and future surveys. This imaging will not only enhance other surveys, but also facilitate completely new science. By imaging the full sky over two epochs, Roman can measure the proper motions for stars across the entire Milky Way, probing 100 times fainter than Gaia out to the very edge of the Galaxy. Here, we propose NANCY: a completely public, all-sky survey that will create a high-value legacy dataset benefiting innumerable ongoing and forthcoming studies of the universe. NANCY is a pure expression of Roman's potential: it images the entire sky, at high spatial resolution, in a broad infrared bandpass that collects as many photons as possible. The majority of all ongoing astronomical surveys would benefit from incorporating observations of NANCY into their analyses, whether these surveys focus on nearby stars, the Milky Way, near-field cosmology, or the broader universe. △ Less

Submitted 20 June, 2023; originally announced June 2023.

Comments: Submitted to the call for white papers for the Roman Core Community Survey (June 16th, 2023), and to the Bulletin of the AAS

A Diverse Population of z ~ 2 ULIRGs Revealed by JWST Imaging

Authors: J. -S. Huang, Zi-Jian Li, Cheng Cheng, Meicun Hou, Haojing Yan, S. P. Willner, Y. -S. Dai, X. Z. Zheng, J. Pan, D. Rigopoulou, T. Wang, Zhiyuan Li, Piaoran Liang, A. Esamdin, G. G. Fazio

Abstract: Four ultra-luminous infrared galaxies (ULIRGs) observed with JWST/NIRcam in the Cosmos Evolution Early Release Science program offer an unbiased preview of the $z\approx2$ ULIRG population. The objects were originally selected at 24 $μ$m and have strong polycyclic aromatic hydrocarbon emission features observed with Spitzer/IRS. The four objects have similar stellar masses of ${\sim}10^{11}$ M… ▽ More Four ultra-luminous infrared galaxies (ULIRGs) observed with JWST/NIRcam in the Cosmos Evolution Early Release Science program offer an unbiased preview of the $z\approx2$ ULIRG population. The objects were originally selected at 24 $μ$m and have strong polycyclic aromatic hydrocarbon emission features observed with Spitzer/IRS. The four objects have similar stellar masses of ${\sim}10^{11}$ M$_\odot$ but otherwise are quite diverse. One is an isolated disk galaxy, but it has an active nucleus as shown by X-ray observations and by a bright point-source nucleus. Two others are merging pairs with mass ratios of 6-7:1. One has active nuclei in both components, while the other has only one active nucleus: the one in the less-massive neighbor, not the ULIRG. The fourth object is clumpy and irregular and is probably a merger, but there is no sign of an active nucleus. The intrinsic spectral energy distributions for the four AGNs in these systems are typical of type-2 QSOs. This study is consistent with the idea that even if internal processes can produce large luminosities at $z\sim2$, galaxy merging may still be necessary for the most luminous objects. The diversity of these four initial examples suggests that large samples will be needed to understand the $z\approx2$ ULIRG population. △ Less

Submitted 6 April, 2023; v1 submitted 3 April, 2023; originally announced April 2023.

Comments: 9 pages, 3 figures, 1 table, accepted for publication in ApJ. V2 updates author affiliations and acknowledgments, not scientific content

Matrix Weights and Regularity for Degenerate Elliptic Equations

Authors: Giuseppe Di Fazio, Maria Stella Fanciullo, Dario Daniele Monticelli, Scott Rodney, Pietro Zamboni

Abstract: We prove local boundedness, Harnack's inequality and local regularity for weak solutions of quasilinear degenerate elliptic equations in divergence form with Rough coefficients. Degeneracy is encoded by a non-negative, symmetric, measurable matrix valued function Q(x) and two suitable non-negative weight functions. We setup an axiomatic approach in terms of suitable geometric conditions and local… ▽ More We prove local boundedness, Harnack's inequality and local regularity for weak solutions of quasilinear degenerate elliptic equations in divergence form with Rough coefficients. Degeneracy is encoded by a non-negative, symmetric, measurable matrix valued function Q(x) and two suitable non-negative weight functions. We setup an axiomatic approach in terms of suitable geometric conditions and local Sobolev-Poincaré inequalities. Data integrability is close to L1 and is exploited in terms of a suitable Stummel-Kato class that in some cases is necessary for local regularity. △ Less

Submitted 4 February, 2023; originally announced February 2023.

MSC Class: 35J70; 35J60; 35B65

The JCMT SCUBA-2 Survey of the James Webb Space Telescope North Ecliptic Pole Time-Domain Field

Authors: Minhee Hyun, Myungshin Im, Ian R. Smail, William D. Cotton, Jack E. Birkin, Satoshi Kikuta, Hyunjin Shim, Christopher N. A. Willmer, James J. Condon, Rogier A. Windhorst, Seth H. Cohen, Rolf A. Jansen, Chun Ly, Yuichi Matsuda, Giovanni G. Fazio, A. M. Swinbank, Haojing Yan

Abstract: The James Webb Space Telescope Time-Domain Field (JWST-TDF) is an $\sim$14$'$ diameter field near the North Ecliptic Pole that will be targeted by one of the JWST Guaranteed Time Observations programs. Here, we describe our James Clerk Maxwell Telescope SCUBA-2 850 $μ$m imaging of the JWST-TDF and present the submillimeter source catalog and properties. We also present a catalog of radio sources f… ▽ More The James Webb Space Telescope Time-Domain Field (JWST-TDF) is an $\sim$14$'$ diameter field near the North Ecliptic Pole that will be targeted by one of the JWST Guaranteed Time Observations programs. Here, we describe our James Clerk Maxwell Telescope SCUBA-2 850 $μ$m imaging of the JWST-TDF and present the submillimeter source catalog and properties. We also present a catalog of radio sources from Karl J. Jansky Very Large Array 3 GHz observations of the field. These observations were obtained to aid JWST's study of the dust-obscured galaxies that contribute significantly to the cosmic star formation at high redshifts. Our deep 850 $μ$m map covers the JWST TDF at a noise level of $σ_{850}$ = 1.0 mJy beam$^{-1}$, detecting 83/31 sources in the main/supplementary signal-to-noise ratio (S/N $>$ 4 / S/N = 3.5 - 4) sample respectively. The 3 GHz observations cover a 24$'$ diameter field with a 1 $σ$ noise of 1$μ$Jy beam$^{-1}$ at a 0$.\!\!^{\prime\prime}$7 FWHM. We identified eighty-five 3 GHz counterparts to sixty-six 850 $μ$m sources and then matched these with multiwavelength data from the optical to the mid-infrared wave bands. We performed spectral energy distribution fitting for 61 submillimeter galaxies (SMGs) matched with optical/near-infrared data, and found that SMGs at S/N $>$ 4 have a median value of $z_{phot} = $2.22 $\pm$ 0.12, star formation rates of 300 $\pm$ 40 M$_{\odot}\,{\rm yr^{-1}}$ (Chabrier initial mass function), and typical cold dust masses of 5.9 $\pm$ 0.7 $ \times$ 10$^{8} $M$_{\odot}$, in line with bright SMGs from other surveys. The large cold dust masses indicate correspondingly large cool gas masses, which we suggest are a key factor necessary to drive the high star formation rates seen in this population △ Less

Submitted 7 January, 2023; originally announced January 2023.

Comments: 22 pages, 18 figures (1 extended figure and the full catalog are included), Published in ApJS

Journal ref: ApJS 264 19 (2023)

JWST's PEARLS: Prime Extragalactic Areas for Reionization and Lensing Science: Project Overview and First Results

Authors: Rogier A. Windhorst, Seth H. Cohen, Rolf A. Jansen, Jake Summers, Scott Tompkins, Christopher J. Conselice, Simon P. Driver, Haojing Yan, Dan Coe, Brenda Frye, Norman Grogin, Anton Koekemoer, Madeline A. Marshall, Rosalia O'Brien, Nor Pirzkal, Aaron Robotham, Russell E. Ryan, Jr., Christopher N. A. Willmer, Timothy Carleton, Jose M. Diego, William C. Keel, Paolo Porto, Caleb Redshaw, Sydney Scheller, Stephen M. Wilkins , et al. (60 additional authors not shown)

Abstract: We give an overview and describe the rationale, methods, and first results from NIRCam images of the JWST "Prime Extragalactic Areas for Reionization and Lensing Science" ("PEARLS") project. PEARLS uses up to eight NIRCam filters to survey several prime extragalactic survey areas: two fields at the North Ecliptic Pole (NEP); seven gravitationally lensing clusters; two high redshift proto-clusters;… ▽ More We give an overview and describe the rationale, methods, and first results from NIRCam images of the JWST "Prime Extragalactic Areas for Reionization and Lensing Science" ("PEARLS") project. PEARLS uses up to eight NIRCam filters to survey several prime extragalactic survey areas: two fields at the North Ecliptic Pole (NEP); seven gravitationally lensing clusters; two high redshift proto-clusters; and the iconic backlit VV 191 galaxy system to map its dust attenuation. PEARLS also includes NIRISS spectra for one of the NEP fields and NIRSpec spectra of two high-redshift quasars. The main goal of PEARLS is to study the epoch of galaxy assembly, AGN growth, and First Light. Five fields, the JWST NEP Time-Domain Field (TDF), IRAC Dark Field (IDF), and three lensing clusters, will be observed in up to four epochs over a year. The cadence and sensitivity of the imaging data are ideally suited to find faint variable objects such as weak AGN, high-redshift supernovae, and cluster caustic transits. Both NEP fields have sightlines through our Galaxy, providing significant numbers of very faint brown dwarfs whose proper motions can be studied. Observations from the first spoke in the NEP TDF are public. This paper presents our first PEARLS observations, their NIRCam data reduction and analysis, our first object catalogs, the 0.9-4.5 $μ$m galaxy counts and Integrated Galaxy Light. We assess the JWST sky brightness in 13 NIRCam filters, yielding our first constraints to diffuse light at 0.9-4.5 μm. PEARLS is designed to be of lasting benefit to the community. △ Less

Submitted 28 November, 2022; v1 submitted 9 September, 2022; originally announced September 2022.

Comments: Accepted to AJ, comments welcome. We ask anyone who uses our public PEARLS (NEP TDF) data to refer to this overview paper

Webb's PEARLS: Bright 1.5--2.0 micron Dropouts in the Spitzer/IRAC Dark Field

Authors: Haojing Yan, Seth H. Cohen, Rogier A. Windhorst, Rolf A. Jansen, Zhiyuan Ma, John F. Beacom, Cheng Cheng, Jia-Sheng Huang, Norman A. Grogin, S. P. Willner, Min Yun, Heidi B. Hammel, Stefanie N. Milam, Christopher J. Conselice, Simon P. Driver, Brenda Frye, Madeline A. Marshall, Anton Koekemoer, Christopher N. A. Willmer, Aaron Robotham, Jordan C. J. D'Silva, Jake Summers, Chenxiaoji Ling, Jeremy Lim, Kevin Harrington , et al. (13 additional authors not shown)

Abstract: Using the first epoch of four-band NIRCam observations obtained by the James Webb Space Telescope (JWST) Prime Extragalactic Areas for Reionization and Lensing Science Program in the Spitzer IRAC Dark Field, we search for F150W and F200W dropouts. In 14.2 arcmin^2, we have found eight F150W dropouts and eight F200W dropouts, all brighter than 27.5 mag (the brightest being ~24 mag) in the band to t… ▽ More Using the first epoch of four-band NIRCam observations obtained by the James Webb Space Telescope (JWST) Prime Extragalactic Areas for Reionization and Lensing Science Program in the Spitzer IRAC Dark Field, we search for F150W and F200W dropouts. In 14.2 arcmin^2, we have found eight F150W dropouts and eight F200W dropouts, all brighter than 27.5 mag (the brightest being ~24 mag) in the band to the red side of the break. As they are detected in multiple bands, these must be real objects. Their nature, however, is unclear, and characterizing their properties is important for realizing the full potential of JWST. If the observed color decrements are due to the Lyman break, these objects should be at z >~ 11.7 and z >~ 15.4, respectively. The color diagnostics show that at least four F150W dropouts are far away from the usual contaminators encountered in dropout searches (red galaxies at much lower redshifts or brown dwarf stars). While the diagnostics of the F200W dropouts are less certain due to the limited number of passbands, at least one of them is likely not a known type of contaminant, and the rest are consistent with either high-redshift galaxies with evolved stellar populations or old galaxies at z ~ 3 to 8. If a significant fraction of our dropouts are indeed at z ~ 12, we have to face the severe problem of explaining their high luminosities and number densities. Spectroscopic identifications of such objects are urgently needed. △ Less

Submitted 7 December, 2022; v1 submitted 8 September, 2022; originally announced September 2022.

Comments: Accepted for publication in ApJL

Multi-wavelength Variability of Sagittarius A* in July 2019

Authors: H. Boyce, D. Haggard, G. Witzel, S. von Fellenberg, S. P. Willner, E. E. Becklin, T. Do, A. Eckart, G. G. Fazio, M. A. Gurwell, J. L. Hora, S. Markoff, M. R. Morris, J. Neilsen, M. Nowak, H. A. Smith, S. Zhang

Abstract: We report timing analysis of near-infrared (NIR), X-ray, and sub-millimeter (submm) data during a three-day coordinated campaign observing Sagittarius A*. Data were collected at 4.5 micron with the Spitzer Space Telescope, 2-8 keV with the Chandra X-ray Observatory, 3-70 keV with NuSTAR, 340 GHz with ALMA, and at 2.2 micron with the GRAVITY instrument on the Very Large Telescope Interferometer. Tw… ▽ More We report timing analysis of near-infrared (NIR), X-ray, and sub-millimeter (submm) data during a three-day coordinated campaign observing Sagittarius A*. Data were collected at 4.5 micron with the Spitzer Space Telescope, 2-8 keV with the Chandra X-ray Observatory, 3-70 keV with NuSTAR, 340 GHz with ALMA, and at 2.2 micron with the GRAVITY instrument on the Very Large Telescope Interferometer. Two dates show moderate variability with no significant lags between the submm and the infrared at 99% confidence. July 18 captured a moderately bright NIR flare (F_K ~ 15 mJy) simultaneous with an X-ray flare (F ~ 0.1 cts/s) that most likely preceded bright submm flux (F ~ 5.5 Jy) by about +34 (+14 -33) minutes at 99% confidence. The uncertainty in this lag is dominated by the fact that we did not observe the peak of the submm emission. A synchrotron source cooled through adiabatic expansion can describe a rise in the submm once the synchrotron-self-Compton NIR and X-ray peaks have faded. This model predicts high GHz and THz fluxes at the time of the NIR/X-ray peak and electron densities well above those implied from average accretion rates for Sgr A*. However, the higher electron density postulated in this scenario would be in agreement with the idea that 2019 was an extraordinary epoch with a heightened accretion rate. Since the NIR and X-ray peaks can also be fit by a non-thermal synchrotron source with lower electron densities, we cannot rule out an unrelated chance coincidence of this bright submm flare with the NIR/X-ray emission. △ Less

Submitted 24 March, 2022; originally announced March 2022.

Comments: Accepted for publication in The Astrophysical Journal

Constraining particle acceleration in Sgr A* with simultaneous GRAVITY, Spitzer, NuSTAR and Chandra observations

Authors: R. Abuter, A. Amorim, M. Bauböck, F. Baganoff, J. P. Berge, H. Boyce, H. Bonnet, W. Brandner, Y. Clénet, R. Davies, P. T. de Zeeuw, J. Dexter, Y. Dallilar, A. Drescher, A. Eckart, F. Eisenhauer, G. G. Fazio, N. M. Förster Schreiber, K. Foster, C. Gammie, P. Garcia, F. Gao, E. Gendron, R. Genzel, G. Ghisellini , et al. (59 additional authors not shown)

Abstract: We report the time-resolved spectral analysis of a bright near-infrared and moderate X-ray flare of Sgr A*. We obtained light curves in the $M$-, $K$-, and $H$-bands in the mid- and near-infrared and in the $2-8~\mathrm{keV}$ and $2-70~\mathrm{keV}$ bands in the X-ray. The observed spectral slope in the near-infrared band is $νL_ν\propto ν^{0.5\pm0.2}$; the spectral slope observed in the X-ray ban… ▽ More We report the time-resolved spectral analysis of a bright near-infrared and moderate X-ray flare of Sgr A*. We obtained light curves in the $M$-, $K$-, and $H$-bands in the mid- and near-infrared and in the $2-8~\mathrm{keV}$ and $2-70~\mathrm{keV}$ bands in the X-ray. The observed spectral slope in the near-infrared band is $νL_ν\propto ν^{0.5\pm0.2}$; the spectral slope observed in the X-ray band is $νL_ν\propto ν^{-0.7\pm0.5}$. We tested synchrotron and synchrotron self-Compton (SSC) scenarios. The observed near-infrared brightness and X-ray faintness, together with the observed spectral slopes, pose challenges for all models explored. We rule out a scenario in which the near-infrared emission is synchrotron emission and the X-ray emission is SSC. A one-zone model in which both the near-infrared and X-ray luminosity are produced by SSC and a model in which the luminosity stems from a cooled synchrotron spectrum can explain the flare. In order to describe the mean SED, both models require specific values of the maximum Lorentz factor $γ_{max}$, which however differ by roughly two orders of magnitude: the SSC model suggests that electrons are accelerated to $γ_{max}\sim 500$, while cooled synchrotron model requires acceleration up to $γ_{max}\sim5\times 10^{4}$. The SSC scenario requires electron densities of $10^{10}~\mathrm{cm^{-3}}$ much larger than typical ambient densities in the accretion flow, and thus require in an extraordinary accretion event. In contrast, assuming a source size of $1R_s$, the cooled synchrotron scenario can be realized with densities and magnetic fields comparable with the ambient accretion flow. For both models, the temporal evolution is regulated through the maximum acceleration factor $γ_{max}$, implying that sustained particle acceleration is required to explain at least a part of the temporal evolution of the flare. △ Less

Submitted 2 July, 2021; originally announced July 2021.

Comments: accepted for publication in Astronomy & Astrophysics; preview abstract shortened due to arXiv requirements

Journal ref: A&A 654, A22 (2021)

Beyond Simple AGN Unification with Chandra-observed 3CRR Sources

Authors: Joanna Kuraszkiewicz, Belinda J. Wilkes, Adam Atanas, Johannes Buchner, Jonathan C. McDowell, S. P. Willner, Matthew L. N. Ashby, Mojegan Azadi, Peter Barthel, Martin Haas, Diana M. Worrall, Mark Birkinshaw, Robert Antonucci, Rolf Chini, Giovanni G. Fazio, Charles Lawrence, Patrick Ogle

Abstract: Low-frequency radio selection finds radio-bright galaxies regardless of the amount of obscuration by gas and dust. We report \chandra\ observations of a complete 178~MHz-selected, and so orientation unbiased, sample of 44 $0.5<z<1$ 3CRR sources. The sample is comprised of quasars and narrow-line radio galaxies (NLRGs) with similar radio luminosities, and the radio structure serves as both an age a… ▽ More Low-frequency radio selection finds radio-bright galaxies regardless of the amount of obscuration by gas and dust. We report \chandra\ observations of a complete 178~MHz-selected, and so orientation unbiased, sample of 44 $0.5<z<1$ 3CRR sources. The sample is comprised of quasars and narrow-line radio galaxies (NLRGs) with similar radio luminosities, and the radio structure serves as both an age and an orientation indicator. Consistent with Unification, intrinsic obscuration (measured by \nh, X-ray hardness ratio, and X-ray luminosity) generally increases with inclination. However, the sample includes a population not seen in high-$z$ 3CRR sources: NLRGs viewed at intermediate inclination angles with \nh~$<10^{22}$~cm$^{-2}$. Multiwavelength analysis suggests these objects have lower $L/L_{\rm Edd}$ than typical NLRGs at similar orientation. Thus both orientation and $L/L_{\rm Edd}$ are important, and a "radiation-regulated Unification" provides a better explanation of the sample's observed properties. In comparison with the 3CRR sample at $1<z<2$, our lower-redshift sample shows a higher fraction of Compton-thin NLRGs (45\% vs.\ 29\%) but similar Compton-thick fraction (20\%), implying a larger covering factor of Compton-thin material at intermediate viewing angles and so a more "puffed-up" torus atmosphere. We posit that this is due to a range of $L/L_{\rm Edd}$ extending to lower values in this sample. In contrast, at high redshifts the narrower range and high $L/L_{\rm Edd}$ values allowed orientation (and so simple Unification) to dominate the sample's observed properties. △ Less

Submitted 27 April, 2021; originally announced April 2021.

A Complete 16 micron-Selected Galaxy Sample at $z\sim1$: Mid-infrared Spectral Energy Distributions

Authors: J. -S. Huang, Y. -S. Dai, S. P. Willner, S. M. Faber, C. Cheng, H. Xu, S. Wu, X. Shao, C. Hao, X. Xia, D. Rigopoulou, M. Pereira Santaella, G. Magdis, I. Cortzen, H. Yan, G. Fazio, P. Assmann, N. Araneda, L. Fan, M. Musin, Z. Wang, K. C. Xu, C. He, A. Esamdin

Abstract: We describe a complete, flux-density-limited sample of galaxies at redshift $0.8 < z < 1.3$ selected at 16 micron. At the selection wavelength near 8 micron rest, the observed emission comes both from dust heated by intense star formation and from active galactic nuclei (AGNs). Fitting the spectral energy distributions (SEDs) of the sample galaxies to local-galaxy templates reveals that more than… ▽ More We describe a complete, flux-density-limited sample of galaxies at redshift $0.8 < z < 1.3$ selected at 16 micron. At the selection wavelength near 8 micron rest, the observed emission comes both from dust heated by intense star formation and from active galactic nuclei (AGNs). Fitting the spectral energy distributions (SEDs) of the sample galaxies to local-galaxy templates reveals that more than half the galaxies have SEDs dominated by star formation. About one sixth of the galaxy SEDs are dominated by an AGN, and nearly all the rest of the SEDs are composite. Comparison with X-ray and far-infrared observations shows that combinations of luminosities at rest-frame 4.5 and 8 micron give good measures of both AGN luminosity and star-formation rate. The sample galaxies mostly follow the established star-forming main sequence for $z=1$ galaxies, but of the galaxies more than 0.5 dex above that main sequence, more than half have AGN-type SEDs. Similarly, the most luminous AGNs tend to have higher star-formation rates than the main sequence value. Galaxies with stellar masses $>$10$^{11}$\,\Msun\ are unlikely to host an AGN. About 1% of the sample galaxies show an SED with dust emission typical of neither star formation nor an AGN. △ Less

Submitted 28 April, 2021; v1 submitted 8 March, 2021; originally announced March 2021.

Comments: 14 pages, 5 tables, 29 figures, ApJ accepted v2 corrects author name formatting

Spitzer IRAC observations of JWST calibration stars

Authors: Jessica E. Krick, Patrick Lowrance, Sean Carey, Seppo Laine, Carl Grillmair, Schuyler D. Van Dyk, William J. Glaccum, James G. Ingalls, George Rieke, Joseph L. Hora, Giovanni G. Fazio, Karl D. Gordon, Ralph C. Bohlin

Abstract: We present infrared photometry of all 36 potential JWST calibrators for which there is archival Spitzer IRAC data. This photometry can then be used to inform stellar models necessary to provide absolute calibration for all JWST instruments. We describe in detail the steps necessary to measure IRAC photometry from archive retrieval to photometric corrections. To validate our photometry we examine t… ▽ More We present infrared photometry of all 36 potential JWST calibrators for which there is archival Spitzer IRAC data. This photometry can then be used to inform stellar models necessary to provide absolute calibration for all JWST instruments. We describe in detail the steps necessary to measure IRAC photometry from archive retrieval to photometric corrections. To validate our photometry we examine the distribution of uncertainties from all detections in all four IRAC channels as well as compare the photometry and its uncertainties to those from models, ALLWISE, and the literature. 75% of our detections have standard deviations per star of all observations within each channel of less than three percent. The median standard deviations are 1.2, 1.3, 1.1, and 1.9% in [3.6] - [8.0] respectively. We find less than 8% standard deviations in differences of our photometry with ALLWISE, and excellent agreement with literature values (less than 3% difference) lending credence to our measured fluxes. JWST is poised to do ground-breaking science, and accurate calibration and cross-calibration with other missions will be part of the underpinnings of that science. △ Less

Submitted 3 February, 2021; originally announced February 2021.

Comments: 16 pages, 5 figures, AJ accepted

The VANDELS ESO public spectroscopic survey: final Data Release of 2087 spectra and spectroscopic measurements

Authors: B. Garilli, R. McLure, L. Pentericci, P. Franzetti, A. Gargiulo, A. Carnall, O. Cucciati, A. Iovino, R. Amorin, M. Bolzonella, A. Bongiorno, M. Castellano, A. Cimatti, M. Cirasuolo, F. Cullen, J. Dunlop, D. Elbaz, S. Finkelstein, A. Fontana, F. Fontanot, M. Fumana, L. Guaita, W. Hartley, M. Jarvis, S. Juneau , et al. (72 additional authors not shown)

Abstract: VANDELS is an ESO Public Spectroscopic Survey designed to build a sample of high signal to noise, medium resolution spectra of galaxies at redshift between 1 and 6.5. Here we present the final Public Data Release of the VANDELS Survey, comprising 2087 redshift measurements. We give a detailed description of sample selection, observations and data reduction procedures. The final catalogue reaches a… ▽ More VANDELS is an ESO Public Spectroscopic Survey designed to build a sample of high signal to noise, medium resolution spectra of galaxies at redshift between 1 and 6.5. Here we present the final Public Data Release of the VANDELS Survey, comprising 2087 redshift measurements. We give a detailed description of sample selection, observations and data reduction procedures. The final catalogue reaches a target selection completeness of 40% at iAB = 25. The high Signal to Noise ratio of the spectra (above 7 in 80% of the spectra) and the dispersion of 2.5Å allowed us to measure redshifts with high precision, the redshift measurement success rate reaching almost 100%. Together with the redshift catalogue and the reduced spectra, we also provide optical mid-IR photometry and physical parameters derived through SED fitting. The observed galaxy sample comprises both passive and star forming galaxies covering a stellar mass range 8.3< Log(M*/Msolar)<11.7. All catalogues and spectra are accessible through the survey database (http://vandels.inaf.it) where all information can be queried interactively, and via the ESO Archive (https://www.eso.org/qi/). △ Less

Submitted 19 January, 2021; originally announced January 2021.

Comments: 16 pages, 13 figures, accepted for publication in Astronomy & Astrophysics

Journal ref: A&A 647, A150 (2021)

Rapid Variability of Sgr A* across the Electromagnetic Spectrum

Authors: G. Witzel, G. Martinez, S. P. Willner, E. E. Becklin, 4 H. Boyce, T. Do, A. Eckart, G. G. Fazio, A. Ghez, M. A. Gurwell, D. Haggard, R. Herrero-Illana, J. L. Hora, Z. Li, J. Liu, N. Marchili, Mark R. Morris, Howard A. Smith, M. Subroweit, J. A. Zensus

Abstract: Sagittarius A* (Sgr A*) is the variable radio, near-infrared (NIR), and X-ray source associated with accretion onto the Galactic center black hole. We have analyzed a comprehensive submillimeter (including new observations simultaneous with NIR monitoring), NIR, and 2-8 keV dataset. Submillimeter variations tend to lag those in the NIR by $\sim$30 minutes. An approximate Bayesian computation (ABC)… ▽ More Sagittarius A* (Sgr A*) is the variable radio, near-infrared (NIR), and X-ray source associated with accretion onto the Galactic center black hole. We have analyzed a comprehensive submillimeter (including new observations simultaneous with NIR monitoring), NIR, and 2-8 keV dataset. Submillimeter variations tend to lag those in the NIR by $\sim$30 minutes. An approximate Bayesian computation (ABC) fit to the X-ray first-order structure function shows significantly less power at short timescales in the X-rays than in the NIR. Less X-ray variability at short timescales combined with the observed NIR-X-ray correlations means the variability can be described as the result of two strictly correlated stochastic processes, the X-ray process being the low-pass-filtered version of the NIR process. The NIR--X-ray linkage suggests a simple radiative model: a compact, self-absorbed synchrotron sphere with high-frequency cutoff close to NIR frequencies plus a synchrotron self-Compton scattering component at higher frequencies. This model, with parameters fit to the submillimeter, NIR, and X-ray structure functions, reproduces the observed flux densities at all wavelengths, the statistical properties of all light curves, and the time lags between bands. The fit also gives reasonable values for physical parameters such as magnetic flux density $B\approx13$ G, source size $L \approx2.2R_{S}$, and high-energy electron density $n_{e}\approx4\times10^{7}$ cm$^{-3}$. An animation illustrates typical light curves, and we make public the parameter chain of our Bayesian analysis, the model implementation, and the visualization code. △ Less

Submitted 7 June, 2021; v1 submitted 18 November, 2020; originally announced November 2020.

Comments: Accepted by ApJS, June 3, 2021. The journal version of figure 21 is animated. The animation can also be found here: https://doi.org/10.17617/1.kctx3s25. This version (version 2) has been revised according to the referee's suggestions and includes optimized figures and some changes and corrections of the text; no scientific conclusions have changed

Disentangling the AGN and Star-Formation Contributions to the Radio-X-ray Emission of Radio-Loud Quasars at 1<z<2

Authors: Mojegan Azadi, Belinda Wilkes, Joanna Kuraszkiewicz, Jonathan McDowell, Ralf Siebenmorgen, Matthew Ashby, Mark Birkinshaw, Diana Worrall, Natasha Abrams, Peter Barthel, Giovanni Fazio, Martin Haas, Sóley Hyman, Rafael Martínez-Galarza, Eileen Meyer

Abstract: We constrain the emission mechanisms responsible for the prodigious electromagnetic output generated by active galactic nuclei (AGN) and their host galaxies with a novel state-of-the-art AGN radio- to-X-ray spectral energy distribution model fitting code (ARXSED). ARXSED combines multiple components to fit the spectral energy distributions (SEDs) of AGN and their host galaxies. Emission components… ▽ More We constrain the emission mechanisms responsible for the prodigious electromagnetic output generated by active galactic nuclei (AGN) and their host galaxies with a novel state-of-the-art AGN radio- to-X-ray spectral energy distribution model fitting code (ARXSED). ARXSED combines multiple components to fit the spectral energy distributions (SEDs) of AGN and their host galaxies. Emission components include radio structures such as lobes and jets, infrared emission from the AGN torus, visible-to-X-ray emission from the accretion disk, and radio-to-ultraviolet emission from the host galaxy. Applying ARXSED to the radio SEDs of 20 3CRR quasars at 1 < z < 2 verifies the need for more than a simple power law when compact radio structures are present. The non-thermal emission contributes 91%-57% of the observed-frame 1.25mm to 850μm flux, and this component must be accounted for when using these wavelengths to estimate star-formation properties. We predict the presence of strong radio-linked X-ray emission in more than half the sample sources. ARXSED estimates median (and the associated first and third quartile ranges) BH mass of $2.9_{1.7}^{6.0} \times 10^9~\rm M_{\odot}$, logarithm of Eddington ratio of $ -1.0_{-1.2}^{-0.6} $, and spin of $ 0.98_{0.94}^{0.99} $ for our sample. The inferred AGN torus and accretion disk parameters agree with those estimated from spectroscopic analyses of similar samples in the literature. We present the median intrinsic SED of the luminous radio-loud quasars at 1 < z < 2 ; this SED represents a significant improvement in the way each component is modeled. △ Less

Submitted 24 February, 2023; v1 submitted 5 November, 2020; originally announced November 2020.

The CANDELS/SHARDS multi-wavelength catalog in GOODS-N: Photometry, Photometric Redshifts, Stellar Masses, Emission line fluxes and Star Formation Rates

Authors: Guillermo Barro, Pablo G. Perez-Gonzalez, Antonio Cava, Gabriel Brammer, Viraj Pandya, Carmen Eliche Moral, Pilar Esquej, Helena Dominguez-Sanchez, Belen Alcalde Pampliega, Yicheng Guo, Anton M. Koekemoer, Jonathan R. Trump, Matthew L. N. Ashby, Nicolas Cardiel, Marco Castellano, Christopher J. Conselice, Mark E. Dickinson, Timothy Dolch, Jennifer L. Donley, Nestor Espino Briones, Sandra M. Faber, Giovanni G. Fazio, Henry Ferguson, Steve Finkelstein, Adriano Fontana , et al. (30 additional authors not shown)

Abstract: We present a WFC3 F160W ($H$-band) selected catalog in the CANDELS/GOODS-N field containing photometry from the ultraviolet (UV) to the far-infrared (IR), photometric redshifts and stellar parameters derived from the analysis of the multi-wavelength data. The catalog contains 35,445 sources over the 171 arcmin$^{2}$ of the CANDELS F160W mosaic. The 5$σ$ detection limits (within an aperture of radi… ▽ More We present a WFC3 F160W ($H$-band) selected catalog in the CANDELS/GOODS-N field containing photometry from the ultraviolet (UV) to the far-infrared (IR), photometric redshifts and stellar parameters derived from the analysis of the multi-wavelength data. The catalog contains 35,445 sources over the 171 arcmin$^{2}$ of the CANDELS F160W mosaic. The 5$σ$ detection limits (within an aperture of radius 0\farcs17) of the mosaic range between $H=27.8$, 28.2 and 28.7 in the wide, intermediate and deep regions, that span approximately 50\%, 15\% and 35\% of the total area. The multi-wavelength photometry includes broad-band data from UV (U band from KPNO and LBC), optical (HST/ACS F435W, F606W, F775W, F814W, and F850LP), near-to-mid IR (HST/WFC3 F105W, F125W, F140W and F160W, Subaru/MOIRCS Ks, CFHT/Megacam K, and \spitzer/IRAC 3.6, 4.5, 5.8, 8.0 $μ$m) and far IR (\spitzer/MIPS 24$μ$m, HERSCHEL/PACS 100 and 160$μ$m, SPIRE 250, 350 and 500$μ$m) observations. In addition, the catalog also includes optical medium-band data (R$\sim50$) in 25 consecutive bands, $λ=500$ to 950~nm, from the SHARDS survey and WFC3 IR spectroscopic observations with the G102 and G141 grisms (R$\sim210$ and 130). The use of higher spectral resolution data to estimate photometric redshifts provides very high, and nearly uniform, precision from $z=0-2.5$. The comparison to 1,485 good quality spectroscopic redshifts up to $z\sim3$ yields $Δz$/(1+$z_{\rm spec}$)$=$0.0032 and an outlier fraction of $η=$4.3\%. In addition to the multi-band photometry, we release added-value catalogs with emission line fluxes, stellar masses, dust attenuations, UV- and IR- based star formation rates and rest-frame colors. △ Less

Submitted 1 August, 2019; originally announced August 2019.

Comments: The catalogs, images and spectra are available in Rainbow-slicer (https://bit.ly/2OxKKx1 ), navigator (https://bit.ly/2GDS180 ) and MAST (https://bit.ly/2YtoBQ4 ). In addition to the photometry and other added-value catalogs we release UV+IR star formation rates based on Spitzer (MIPS) and Herschel (PACS and SPIRE) in the 5 CANDELS fields

Journal ref: The Astrophysical Journal Supplement Series, Volume 243, Number 2, 2019

Interfacing CRYSTAL/AMBER to Optimize QM/MM Lennard-Jones Parameters for Water and to Study Solvation of TiO2 Nanoparticles

Authors: Asmus Ougaard Doh, Daniele Selli, Gianluca Fazio, Lorenzo Ferraro, Jens Jørgen Mortensen, Bartolomeo Civalleri, Cristiana Di Valentin

Abstract: Metal oxide nanoparticles (NPs) are regarded as good candidates for many technological applications, where their functional environment is often an aqueous solution. The correct description of metal oxide electronic structure is still a challenge for local and semilocal density functionals, whereas hybrid functional methods provide an improved description, and local atomic function based codes suc… ▽ More Metal oxide nanoparticles (NPs) are regarded as good candidates for many technological applications, where their functional environment is often an aqueous solution. The correct description of metal oxide electronic structure is still a challenge for local and semilocal density functionals, whereas hybrid functional methods provide an improved description, and local atomic function based codes such as CRYSTAL17 outperform plane wave codes when it comes to hybrid functional calculations. However, the computational cost of hybrids are still prohibitive for systems of real sizes, in a real environment. Therefore, we here present and critically assess the accuracy of our electrostatic embedding quantum mechanical/molecular mechanical (QM/MM) coupling between CRYSTAL17 and AMBER16, and demonstrate some of its capabilities via the case study of TiO2 NPs in water. First, we produced new Lennard-Jones (LJ) parameters that improve the accuracy of water-water interactions in the B3LYP/TIP3P coupling. Then, we applied our QM/MM coupling methodology to describe the interaction of a 1 nm wide multilayer of water surrounding a spherical TiO2 nanoparticle (NP). Optimizing the QM/MM water water parameters was found to have little to no effect on the local NP properties, which provide insights into the range of influence that can be attributed to the LJ term in the QM/MM coupling. The effect of adding additional water in an MM fashion on the geometry optimized nanoparticle structure is small, but more evident effects are seen in its electronic properties. We also show that there is good transferability of existing QM/MM LJ parameters for organic molecules water interactions to our QM/MM implementation, even though these parameters were obtained with a different QM code and QM/MM implementation, but with the same functional. △ Less

Submitted 20 March, 2019; originally announced March 2019.

Deep ugrizY Imaging and DEEP2/3 Spectroscopy: A Photometric Redshift Testbed for LSST and Public Release of Data from the DEEP3 Galaxy Redshift Survey

Authors: Rongpu Zhou, Michael C. Cooper, Jeffrey A. Newman, Matthew L. N. Ashby, James Aird, Christopher J. Conselice, Marc Davis, Aaron A. Dutton, S. M. Faber, Jerome J. Fang, G. G. Fazio, Puragra Guhathakurta, Dale Kocevski, David C. Koo, Kirpal Nandra, Andrew C. Phillips, David J. Rosario, Edward F. Schlafly, Jonathan R. Trump, Benjamin Weiner, Christopher N. A. Willmer, Renbin Yan

Abstract: We present catalogs of calibrated photometry and spectroscopic redshifts in the Extended Groth Strip, intended for studies of photometric redshifts (photo-z's). The data includes ugriz photometry from CFHTLS and Y-band photometry from the Subaru Suprime camera, as well as spectroscopic redshifts from the DEEP2, DEEP3 and 3D-HST surveys. These catalogs incorporate corrections to produce effectively… ▽ More We present catalogs of calibrated photometry and spectroscopic redshifts in the Extended Groth Strip, intended for studies of photometric redshifts (photo-z's). The data includes ugriz photometry from CFHTLS and Y-band photometry from the Subaru Suprime camera, as well as spectroscopic redshifts from the DEEP2, DEEP3 and 3D-HST surveys. These catalogs incorporate corrections to produce effectively matched-aperture photometry across all bands, based upon object size information available in the catalog and Moffat profile point spread function fits. We test this catalog with a simple machine learning-based photometric redshift algorithm based upon Random Forest regression, and find that the corrected aperture photometry leads to significant improvement in photo-z accuracy compared to the original SExtractor catalogs from CFHTLS and Subaru. The deep ugrizY photometry and spectroscopic redshifts are well-suited for empirical tests of photometric redshift algorithms for LSST. The resulting catalogs are publicly available. We include a basic summary of the strategy of the DEEP3 Galaxy Redshift Survey to accompany the recent public release of DEEP3 data. △ Less

Submitted 12 August, 2019; v1 submitted 19 March, 2019; originally announced March 2019.

Comments: 20 pages, 9 figures; published in MNRAS; for associated catalogs, see http://d-scholarship.pitt.edu/36064/

Journal ref: MNRAS 488, 4565-4584 (2019)

Increasing the Discovery Space in Astrophysics - A Collation of Six Submitted White Papers

Authors: G. Fabbiano, M. Elvis, A. Accomazzi, G. B. Berriman, N. Brickhouse, S. Bose, D. Carrera, I. Chilingarian, F. Civano, B. Czerny, R. D'Abrusco, B. Diemer, J. Drake, R. Emami Meibody, J. R. Farah, G. G. Fazio, E. Feigelson, F. Fornasini, Jay Gallagher, J. Grindlay, L. Hernquist, D. J. James, M. Karovska, V. Kashyap, D. -W. Kim , et al. (24 additional authors not shown)

Abstract: We write in response to the call from the 2020 Decadal Survey to submit white papers illustrating the most pressing scientific questions in astrophysics for the coming decade. We propose exploration as the central question for the Decadal Committee's discussions.The history of astronomy shows that paradigm changing discoveries are not driven by well formulated scientific questions, based on the kn… ▽ More We write in response to the call from the 2020 Decadal Survey to submit white papers illustrating the most pressing scientific questions in astrophysics for the coming decade. We propose exploration as the central question for the Decadal Committee's discussions.The history of astronomy shows that paradigm changing discoveries are not driven by well formulated scientific questions, based on the knowledge of the time. They were instead the result of the increase in discovery space fostered by new telescopes and instruments. An additional tool for increasing the discovery space is provided by the analysis and mining of the increasingly larger amount of archival data available to astronomers. Revolutionary observing facilities, and the state of the art astronomy archives needed to support these facilities, will open up the universe to new discovery. Here we focus on exploration for compact objects and multi messenger science. This white paper includes science examples of the power of the discovery approach, encompassing all the areas of astrophysics covered by the 2020 Decadal Survey. △ Less

Submitted 18 March, 2019; v1 submitted 15 March, 2019; originally announced March 2019.

An Ultra Deep Field survey with WFIRST

Authors: Anton M. Koekemoer, R. J. Foley, D. N. Spergel, M. Bagley, R. Bezanson, F. B. Bianco, R. Bouwens, L. Bradley, G. Brammer, P. Capak, I. Davidzon, G. De Rosa, M. E. Dickinson, O. Doré, J. S. Dunlop, R. S. Ellis, X. Fan, G. G. Fazio, H. C. Ferguson, A. V. Filippenko, S. Finkelstein, B. Frye, E. Gawiser, N. A. Grogin, N. P. Hathi , et al. (47 additional authors not shown)

Abstract: Studying the formation and evolution of galaxies at the earliest cosmic times, and their role in reionization, requires the deepest imaging possible. Ultra-deep surveys like the HUDF and HFF have pushed to mag \mAB$\,\sim\,$30, revealing galaxies at the faint end of the LF to $z$$\,\sim\,$9$\,-\,$11 and constraining their role in reionization. However, a key limitation of these fields is their siz… ▽ More Studying the formation and evolution of galaxies at the earliest cosmic times, and their role in reionization, requires the deepest imaging possible. Ultra-deep surveys like the HUDF and HFF have pushed to mag \mAB$\,\sim\,$30, revealing galaxies at the faint end of the LF to $z$$\,\sim\,$9$\,-\,$11 and constraining their role in reionization. However, a key limitation of these fields is their size, only a few arcminutes (less than a Mpc at these redshifts), too small to probe large-scale environments or clustering properties of these galaxies, crucial for advancing our understanding of reionization. Achieving HUDF-quality depth over areas $\sim$100 times larger becomes possible with a mission like the Wide Field Infrared Survey Telescope (WFIRST), a 2.4-m telescope with similar optical properties to HST, with a field of view of $\sim$1000 arcmin$^2$, $\sim$100$\times$ the area of the HST/ACS HUDF. This whitepaper motivates an Ultra-Deep Field survey with WFIRST, covering $\sim$100$\,-\,$300$\times$ the area of the HUDF, or up to $\sim$1 deg$^2$, to \mAB$\,\sim\,$30, potentially revealing thousands of galaxies and AGN at the faint end of the LF, at or beyond $z$\,$\sim$\,9$\,-\,$10 in the epoch of reionization, and tracing their LSS environments, dramatically increasing the discovery potential at these redshifts. (Note: This paper is a somewhat expanded version of one that was submitted as input to the Astro2020 Decadal Survey, with this version including an Appendix (which exceeded the Astro2020 page limits), describing how the science drivers for a WFIRST Ultra Deep Field might map into a notional observing program, including the filters used and exposure times needed to achieve these depths.) △ Less

Submitted 19 March, 2019; v1 submitted 14 March, 2019; originally announced March 2019.

Populations behind the source-subtracted cosmic infrared background anisotropies

Authors: A. Kashlinsky, R. G. Arendt, M. Ashby, F. Atrio-Barandela, V. Bromm, N. Cappelluti, S. Clesse, A. Comastri, J-G. Cuby, S. Driver, G. Fazio, A. Ferrara, A. Finoguenov, D. Fixsen, J. Garcia-Bellido, G. Hasinger, K. Helgason, R. J. Hill, R. Jansen, J. Kruk, J. Mather, P. Natarajan, N. Odegard, T. Reiprich, M. Ricotti , et al. (5 additional authors not shown)

Abstract: While the upcoming telescopes will reveal correspondingly fainter, more distant galaxies, a question will persist: what more is there that these telescopes cannot see? One answer is the source-subtracted Cosmic Infrared Background (CIB). The CIB is comprised of the collective light from all sources remaining after known, resolved sources are accounted for. Ever-more-sensitive surveys will identify… ▽ More While the upcoming telescopes will reveal correspondingly fainter, more distant galaxies, a question will persist: what more is there that these telescopes cannot see? One answer is the source-subtracted Cosmic Infrared Background (CIB). The CIB is comprised of the collective light from all sources remaining after known, resolved sources are accounted for. Ever-more-sensitive surveys will identify the brightest of these, allowing them to be removed, and - like peeling layers off an onion - reveal deeper layers of the CIB. In this way it is possible to measure the contributions from populations not accessible to direct telescopic observation. Measurement of fluctuations in the source-subtracted CIB, i.e., the spatial power spectrum of the CIB after subtracting resolved sources, provides a robust means of characterizing its faint, and potentially new, populations. Studies over the past 15 years have revealed source-subtracted CIB fluctuations on scales out to ~100' which cannot be explained by extrapolating from known galaxy populations. Moreover, they appear highly coherent with the unresolved Cosmic X-ray Background, hinting at a significant population of accreting black holes among the CIB sources. Characterizing the source-subtracted CIB with high accuracy, and thereby constraining the nature of the new populations, is feasible with upcoming instruments and would produce critically important cosmological information in the next decade. New coextensive deep and wide-area near-infrared, X-ray, and microwave surveys will bring decisive opportunities to examine, with high fidelity, the spatial spectrum and origin of the CIB fluctuations and their cross-correlations with cosmic microwave and X-ray backgrounds, and determine the formation epochs and the nature of the new sources (stellar nucleosynthetic or accreting black holes). △ Less

Submitted 11 March, 2019; originally announced March 2019.

Comments: Science whitepaper submitted to the Astro2020 Decadal Survey

CDIM: Cosmic Dawn Intensity Mapper Final Report

Authors: Asantha Cooray, Tzu-Ching Chang, Stephen Unwin, Michael Zemcov, Andrew Coffey, Patrick Morrissey, Nasrat Raouf, Sarah Lipscy, Mark Shannon, Gordon Wu, Renyue Cen, Ranga Ram Chary, Olivie Doré, Xiaohui Fan, Giovanni G. Fazio, Steven L. Finkelstein, Caroline Heneka, Bomee Lee, Philip Linden, Hooshang Nayyeri, Jason Rhodes, Raphael Sadoun, Marta B. Silva, Hy Trac, Hao-Yi Wu , et al. (1 additional authors not shown)

Abstract: The Cosmic Dawn Intensity Mapper (CDIM) will transform our understanding of the era of reionization when the Universe formed the first stars and galaxies, and UV photons ionized the neutral medium. CDIM goes beyond the capabilities of upcoming facilities by carrying out wide area spectro-imaging surveys, providing redshifts of galaxies and quasars during reionization as well as spectral lines that… ▽ More The Cosmic Dawn Intensity Mapper (CDIM) will transform our understanding of the era of reionization when the Universe formed the first stars and galaxies, and UV photons ionized the neutral medium. CDIM goes beyond the capabilities of upcoming facilities by carrying out wide area spectro-imaging surveys, providing redshifts of galaxies and quasars during reionization as well as spectral lines that carry crucial information on their physical properties. CDIM will make use of unprecedented sensitivity to surface brightness to measure the intensity fluctuations of reionization on large-scales to provide a valuable and complementary dataset to 21-cm experiments. The baseline mission concept is an 83-cm infrared telescope equipped with a focal plane of 24 \times 20482 detectors capable of R = 300 spectro-imaging observations over the wavelength range of 0.75 to 7.5 μm using Linear Variable Filters (LVFs). CDIM provides a large field of view of 7.8 deg2 allowing efficient wide area surveys, and instead of moving instrumental components, spectroscopic mapping is obtained through a shift-and-stare strategy through spacecraft operations. CDIM design and capabilities focus on the needs of detecting faint galaxies and quasars during reionization and intensity fluctuation measurements of key spectral lines, including Lyman-α and Hα radiation from the first stars and galaxies. The design is low risk, carries significant science and engineering margins, and makes use of technologies with high technical readiness level for space observations. △ Less

Submitted 18 March, 2019; v1 submitted 7 March, 2019; originally announced March 2019.

Comments: 62 pages

The Stellar-to-Halo Mass Ratios of Passive and Star-Forming Galaxies at z~2-3 from the SMUVS survey

Authors: William I. Cowley, Karina I. Caputi, Smaran Deshmukh, Matthew L. N. Ashby, Giovanni G. Fazio, Olivier Le Fevre, Johan P. U. Fynbo, Olivier Ilbert, Bo. Milvang-Jensen

Abstract: In this work, we use measurements of galaxy stellar mass and two-point angular correlation functions to constrain the stellar-to-halo mass ratios (SHMRs) of passive and \np\ galaxies at $z\sim2-3$, as identified in the \emph{Spitzer} Matching Survey of the UltraVISTA ultra-deep Stripes (SMUVS). We adopt a sophisticated halo modeling approach to statistically divide our two populations into central… ▽ More In this work, we use measurements of galaxy stellar mass and two-point angular correlation functions to constrain the stellar-to-halo mass ratios (SHMRs) of passive and \np\ galaxies at $z\sim2-3$, as identified in the \emph{Spitzer} Matching Survey of the UltraVISTA ultra-deep Stripes (SMUVS). We adopt a sophisticated halo modeling approach to statistically divide our two populations into central and satellite galaxies. For central galaxies, we find that the normalization of the SHMR is greater for our passive population. Through the modeling of $Λ$ cold dark matter halo mass accretion histories, we show that this can only arise if the conversion of baryons into stars was more efficient at higher redshifts and additionally that passive galaxies can be plausibly explained as residing in halos with the highest formation redshifts (i.e., those with the lowest accretion rates) at a given halo mass. At a fixed stellar mass, satellite galaxies occupy host halos with a greater mass than central galaxies, and we find further that the fraction of passive galaxies that are satellites is higher than for the combined population. This, and our derived satellite quenching timescales, combined with earlier estimates from the literature, support dynamical/environmental mechanisms as the dominant process for satellite quenching at $z\lesssim3$. △ Less

Submitted 19 March, 2019; v1 submitted 29 January, 2019; originally announced January 2019.

Comments: 17 pages, 9 Figures, 1 Table. Accepted for publication in ApJ. Minor changes to previous version

Near-Infrared Survey and Photometric Redshifts in the Extended GOODS-North field

Authors: Li-Ting Hsu, Lihwai Lin, Mark Dickinson, Haojing Yan, Hsieh Bau-Ching, Wei-Hao Wang, Chien-Hsiu Lee, Chi-Hung Yan, Douglas Scott, S. P. Willner, Masami Ouchi, Matthew L. N. Ashby, Yi-Wen Chen, Emanuele Daddi, David Elbaz, Giovanni G. Fazio, Sebastien Foucaud, Jiasheng Huang, David C. Koo, Glenn Morrison, Frazer Owen, Maurilio Pannella, Alexendra Pope, Luc Simard, Shiang-Yu Wang

Abstract: We present deep $J$ and $H$-band images in the extended Great Observatories Origins Deep Survey-North (GOODS-N) field covering an area of 0.22 $\rm{deg}^{2}$. The observations were taken using WIRCam on the 3.6-m Canada France Hawaii Telescope (CFHT). Together with the reprocessed $K_{\rm s}$-band image, the $5σ$ limiting AB magnitudes (in 2" diameter apertures) are 24.7, 24.2, and 24.4 AB mag in… ▽ More We present deep $J$ and $H$-band images in the extended Great Observatories Origins Deep Survey-North (GOODS-N) field covering an area of 0.22 $\rm{deg}^{2}$. The observations were taken using WIRCam on the 3.6-m Canada France Hawaii Telescope (CFHT). Together with the reprocessed $K_{\rm s}$-band image, the $5σ$ limiting AB magnitudes (in 2" diameter apertures) are 24.7, 24.2, and 24.4 AB mag in the $J$, $H$, and $K_{\rm s}$ bands, respectively. We also release a multi-band photometry and photometric redshift catalog containing 93598 sources. For non-X-ray sources, we obtained a photometric redshift accuracy $σ_{\mathrm{NMAD}}=0.036$ with an outlier fraction $η= 7.3\%$. For X-ray sources, which are mainly active galactic nuclei (AGNs), we cross-matched our catalog with the updated 2M-CDFN X-ray catalog from Xue et al. (2016) and found that 658 out of 683 X-ray sources have counterparts. $GALEX$ UV data are included in the photometric redshift computation for the X-ray sources to give $σ_{\mathrm{NMAD}} = 0.040$ with $η=10.5\%$. Our approach yields more accurate photometric redshift estimates compared to previous works in this field. In particular, by adopting AGN-galaxy hybrid templates, our approach delivers photometric redshifts for the X-ray counterparts with fewer outliers compared to the 3D-HST catalog, which fit these sources with galaxy-only templates. △ Less

Submitted 31 December, 2018; originally announced January 2019.

Simultaneous X-ray and Infrared Observations of Sagittarius A*'s Variability

Authors: H. Boyce, D. Haggard, G. Witzel, S. P. Willner, J. Neilsen, J. L. Hora, S. Markoff, G. Ponti, F. Baganoff, E. Becklin, G. Fazio, P. Lowrance, M. R. Morris, H. A. Smith

Abstract: Emission from Sgr A* is highly variable at both X-ray and infrared (IR) wavelengths. Observations over the last ~20 years have revealed X-ray flares that rise above a quiescent thermal background about once per day, while faint X-ray flares from Sgr A* are undetectable below the constant thermal emission. In contrast, the IR emission of Sgr A* is observed to be continuously variable. Recently, sim… ▽ More Emission from Sgr A* is highly variable at both X-ray and infrared (IR) wavelengths. Observations over the last ~20 years have revealed X-ray flares that rise above a quiescent thermal background about once per day, while faint X-ray flares from Sgr A* are undetectable below the constant thermal emission. In contrast, the IR emission of Sgr A* is observed to be continuously variable. Recently, simultaneous observations have indicated a rise in IR flux density around the same time as every distinct X-ray flare, while the opposite is not always true (peaks in the IR emission may not be coincident with an X-ray flare). Characterizing the behaviour of these simultaneous X-ray/IR events and measuring any time lag between them can constrain models of Sgr A*'s accretion flow and the flare emission mechanism. Using 100+ hours of data from a coordinated campaign between the Spitzer Space Telescope and the Chandra X-ray Observatory, we present results of the longest simultaneous IR and X-ray observations of Sgr A* taken to date. The cross-correlation between the IR and X-ray light curves in this unprecedented dataset, which includes four modest X-ray/IR flares, indicates that flaring in the X-ray may lead the IR by approximately 10-20 minutes with 68% confidence. However, the 99.7% confidence interval on the time-lag also includes zero, i.e., the flaring remains statistically consistent with simultaneity. Long duration and simultaneous multiwavelength observations of additional bright flares will improve our ability to constrain the flare timing characteristics and emission mechanisms, and must be a priority for Galactic Center observing campaigns. △ Less

Submitted 13 December, 2018; originally announced December 2018.

Comments: 12 pages, 6 figures, 3 tables, accepted for publication in ApJ

LSST Observing Strategy White Paper: LSST Observations of WFIRST Deep Fields

Authors: R. J. Foley, A. M. Koekemoer, D. N. Spergel, F. B. Bianco, P. Capak, L. Dai, O. Dore, G. G. Fazio, H. Ferguson, A. V. Filippenko, B. Frye, L. Galbany, E. Gawiser, C. Gronwall, N. P. Hathi, C. Hirata, R. Hounsell, S. W. Jha, A. G. Kim, P. L. Kelly, J. W. Kruk, S. Malhotra, K. S. Mandel, R. Margutti, D. Marrone , et al. (16 additional authors not shown)

Abstract: The Wide-Field Infrared Survey Telescope (WFIRST) is expected to launch in the mid-2020s. With its wide-field near-infrared (NIR) camera, it will survey the sky to unprecedented detail. As part of normal operations and as the result of multiple expected dedicated surveys, WFIRST will produce several relatively wide-field (tens of square degrees) deep (limiting magnitude of 28 or fainter) fields. I… ▽ More The Wide-Field Infrared Survey Telescope (WFIRST) is expected to launch in the mid-2020s. With its wide-field near-infrared (NIR) camera, it will survey the sky to unprecedented detail. As part of normal operations and as the result of multiple expected dedicated surveys, WFIRST will produce several relatively wide-field (tens of square degrees) deep (limiting magnitude of 28 or fainter) fields. In particular, a planned supernova survey is expected to image 3 deep fields in the LSST footprint roughly every 5 days over 2 years. Stacking all data, this survey will produce, over all WFIRST supernova fields in the LSST footprint, ~12-25 deg^2 and ~5-15 deg^2 regions to depths of ~28 mag and ~29 mag, respectively. We suggest LSST undertake mini-surveys that will match the WFIRST cadence and simultaneously observe the supernova survey fields during the 2-year WFIRST supernova survey, achieving a stacked depth similar to that of the WFIRST data. We also suggest additional observations of these same regions throughout the LSST survey to get deep images earlier, have long-term monitoring in the fields, and produce deeper images overall. These fields will provide a legacy for cosmology, extragalactic, and transient/variable science. △ Less

Submitted 30 November, 2018; originally announced December 2018.

Comments: White Paper in response to LSST Call for Observing Strategy Input

Keck OSIRIS AO LIRG Analysis: Feedback in the Nuclei of Luminous Infrared Galaxies

Authors: Vivian U, Anne M. Medling, Hanae Inami, Lee Armus, Tanio Díaz-Santos, Vassilis Charmandaris, Justin Howell, Sabrina Stierwalt, George C. Privon, Sean T. Linden, David B. Sanders, Claire E. Max, Aaron S. Evans, Loreto Barcos-Muñoz, Charleston W. K. Chiang, Phil Appleton, Gabriela Canalizo, Giovanni Fazio, Kazushi Iwasawa, Kirsten Larson, Joseph Mazzarella, Eric Murphy, Jeffrey Rich, Jason Surace

Abstract: The role of feedback in triggering or quenching star formation and hence driving galaxy evolution can be directly studied with high resolution integral field observations. The manifestation of feedback in shocks is particularly important to examine in galaxy mergers, where violent interactions of gas takes place in the interstellar medium during the course of the galactic collision. As part of our… ▽ More The role of feedback in triggering or quenching star formation and hence driving galaxy evolution can be directly studied with high resolution integral field observations. The manifestation of feedback in shocks is particularly important to examine in galaxy mergers, where violent interactions of gas takes place in the interstellar medium during the course of the galactic collision. As part of our effort to systematically study the local population of luminous infrared galaxies within the Great Observatories All-Sky LIRG Survey, we undertook the Keck OSIRIS AO LIRG Analysis observing campaign to study the gas dynamics in the inner kiloparsec regions of these systems at spatial scales of a few 10s of parsecs. With high-resolution near-infrared adaptive optics-assisted integral-field observations taken with OSIRIS on the Keck Telescopes, we employ near-infrared diagnostics such as Brg and the ro-vibrationally excited H2 lines to quantify the nuclear star formation rate and identify feedback associated with shocked molecular gas seen in 21 nearby luminous infrared galaxies. Shocked molecular gas is preferentially found in the ultraluminous infrared systems, but may also be triggered at a lower luminosity, earlier merging stage. On circumnuclear scales, AGN have a strong effect on heating the surrounding molecular gas, though their coupling is not simply driven by AGN strength but rather is complicated by orientation, dust shielding, density, and other factors. We find that the nuclear star formation correlates with merger class and diminishing projected nuclear separations. These trends are largely consistent with the picture of merger-induced starbursts within the center of galaxy mergers. △ Less

Submitted 22 November, 2018; originally announced November 2018.

Comments: Accepted to ApJ; 31 pages (with 5 tables and 10 embedded figures) + figure set

Journal ref: 2019 ApJ, 871, 166

Spitzer Observations of Interstellar Object 1I/`Oumuamua

Authors: DE Trilling, M Mommert, JL Hora, D Farnocchia, P Chodas, J Giorgini, HA Smith, S Carey, CM Lisse, M Werner, A McNeill, SR Chesley, JP Emery, G Fazio, YR Fernandez, A Harris, M Marengo, M Mueller, A Roegge, N Smith, HA Weaver, K Meech, M Micheli

Abstract: 1I/`Oumuamua is the first confirmed interstellar body in our Solar System. Here we report on observations of `Oumuamua made with the Spitzer Space Telescope on 2017 November 21--22 (UT). We integrated for 30.2~hours at 4.5 micron (IRAC channel 2). We did not detect the object and place an upper limit on the flux of 0.3 uJy (3sigma). This implies an effective spherical diameter less than [98, 140,… ▽ More 1I/`Oumuamua is the first confirmed interstellar body in our Solar System. Here we report on observations of `Oumuamua made with the Spitzer Space Telescope on 2017 November 21--22 (UT). We integrated for 30.2~hours at 4.5 micron (IRAC channel 2). We did not detect the object and place an upper limit on the flux of 0.3 uJy (3sigma). This implies an effective spherical diameter less than [98, 140, 440] meters and albedo greater than [0.2, 0.1, 0.01] under the assumption of low, middle, or high thermal beaming parameter eta, respectively. With an aspect ratio for `Oumuamua of 6:1, these results correspond to dimensions of [240:40, 341:57, 1080:180] meters, respectively. We place upper limits on the amount of dust, CO, and CO2 coming from this object that are lower than previous results; we are unable to constrain the production of other gas species. Both our size and outgassing limits are important because `Oumuamua's trajectory shows non-gravitational accelerations that are sensitive to size and mass and presumably caused by gas emission. We suggest that `Oumuamua may have experienced low-level post-perihelion volatile emission that produced a fresh, bright, icy mantle. This model is consistent with the expected eta value and implied high albedo value for this solution, but, given our strict limits on CO and CO2, requires another gas species --- probably H2O --- to explain the observed non-gravitational acceleration. Our results extend the mystery of `Oumuamua's origin and evolution. △ Less

Submitted 19 November, 2018; originally announced November 2018.

Journal ref: Published in the Astronomical Journal, 156, 261 (2018)

Regularity estimates in weighted Morrey spaces for quasilinear elliptic equations

Authors: Giuseppe Di Fazio, Truyen Nguyen

Abstract: We study regularity for solutions of quasilinear elliptic equations of the form $÷\A(x,u,\nabla u) = ÷\F $ in bounded domains in $\R^n$. The vector field $\A$ is assumed to be continuous in $u$, and its growth in $\nabla u$ is like that of the $p$-Laplace operator. We establish interior gradient estimates in weighted Morrey spaces for weak solutions $u$ to the equation under a small BMO condition… ▽ More We study regularity for solutions of quasilinear elliptic equations of the form $÷\A(x,u,\nabla u) = ÷\F $ in bounded domains in $\R^n$. The vector field $\A$ is assumed to be continuous in $u$, and its growth in $\nabla u$ is like that of the $p$-Laplace operator. We establish interior gradient estimates in weighted Morrey spaces for weak solutions $u$ to the equation under a small BMO condition in $x$ for $\A$. As a consequence, we obtain that $\nabla u$ is in the classical Morrey space $\calM^{q,λ}$ or weighted space $L^q_w$ whenever $|\F|^{\frac{1}{p-1}}$ is respectively in $\calM^{q,λ}$ or $L^q_w$, where $q$ is any number greater than $p$ and $w$ is any weight in the Muckenhoupt class $A_{\frac{q}{p}}$. In addition, our two-weight estimate allows the possibility to acquire the regularity for $\nabla u$ in a weighted Morrey space that is different from the functional space that the data $|\F|^{\frac{1}{p-1}}$ belongs to. △ Less

Submitted 29 October, 2018; originally announced October 2018.

MSC Class: 30H35; 35B45; 35B65; 35J92

The Star Formation Reference Survey III: A Multi-wavelength View of Star Formation in Nearby Galaxies

Authors: Smriti Mahajan, M. L. N. Ashby, S. P. Willner, P. Barmby, G. G. Fazio, A. Maragkoudakis, S. Raychaudhury, A. Zezas

Abstract: We present multi-wavelength global star formation rate (SFR) estimates for 326 galaxies from the Star Formation Reference Survey (SFRS) in order to determine the mutual scatter and range of validity of different indicators. The widely used empirical SFR recipes based on 1.4 GHz continuum, 8.0 $μ$m polycyclic aromatic hydrocarbons (PAH), and a combination of far-infrared (FIR) plus ultraviolet (UV)… ▽ More We present multi-wavelength global star formation rate (SFR) estimates for 326 galaxies from the Star Formation Reference Survey (SFRS) in order to determine the mutual scatter and range of validity of different indicators. The widely used empirical SFR recipes based on 1.4 GHz continuum, 8.0 $μ$m polycyclic aromatic hydrocarbons (PAH), and a combination of far-infrared (FIR) plus ultraviolet (UV) emission are mutually consistent with scatter of $\raise{-0.8ex}\stackrel{\textstyle <}{\sim }$0.3 dex. The scatter is even smaller, $\raise{-0.8ex}\stackrel{\textstyle <}{\sim }$0.24 dex, in the intermediate luminosity range 9.3<log(L(60 $μ$m/L$_\odot$)<10.7. The data prefer a non-linear relation between 1.4 GHz luminosity and other SFR measures. PAH luminosity underestimates SFR for galaxies with strong UV emission. A bolometric extinction correction to far-ultraviolet luminosity yields SFR within 0.2 dex of the total SFR estimate, but extinction corrections based on UV spectral slope or nuclear Balmer decrement give SFRs that may differ from the total SFR by up to 2 dex. However, for the minority of galaxies with UV luminosity ${>}5\times10^9$ L$_{\odot}$ or with implied far-UV extinction <1 mag, the UV spectral slope gives extinction corrections with 0.22~dex uncertainty. △ Less

Submitted 19 October, 2018; v1 submitted 2 October, 2018; originally announced October 2018.

Comments: To be published in Monthly Notices of the Royal Astronomical Society. Data tables available at https://www.cfa.harvard.edu/irac/SFRS/ . V2 has minor clarifications from V1; no changes in data or results

Role of charged particle emission on the evaporation residue formation in the $^{82}$Se+$^{138}$Ba reaction leading to the $^{220}$Th compound nucleus

Authors: G. Mandaglio, A. K. Nasirov, A. Anastasi, F. Curciarello, G. Fazio, G. Giardina

Abstract: We present detailed results of a theoretical investigation on the production of evaporation residue nuclei obtained in a heavy ion reaction when charged particles (proton and $α$-particle) are also emitted with the neutron evaporation along the deexcitation cascade of the formed compound nucleus. The almost mass symmetric $^{82}$Se+$^{138}$Ba reaction has been studied since there are many experime… ▽ More We present detailed results of a theoretical investigation on the production of evaporation residue nuclei obtained in a heavy ion reaction when charged particles (proton and $α$-particle) are also emitted with the neutron evaporation along the deexcitation cascade of the formed compound nucleus. The almost mass symmetric $^{82}$Se+$^{138}$Ba reaction has been studied since there are many experimental results on individual evaporation residue (ER) cross sections after few light particle emissions along the cascade of the $^{220}$Th compound nucleus (CN) covering the wide 12--70 MeV excitation energy range. Our specific theoretical results on the ER cross sections for the $^{82}$Se+$^{138}$Ba are in good agreement with the available experimental measurements, but our overall theoretical results concerning all possible relevant contributions of evaporation residues are several times greater than the ERs measured in experiment. The discrepancy could be due to the experimental difficulties in the identification of ER nuclei after the emission of multiple neutral and charged particles, nevertheless the analysis of ER data is very important to test the reliability of the model and to stress the importance on the investigation of ER nuclei also obtained after charged particle emissions. △ Less

Submitted 20 September, 2018; originally announced September 2018.

Comments: 16 pages, 4 figures, Accepted for publication in Nucl. Phys. A

Journal ref: Nuclear Physics A 979 (2018) 204