Showing 1–50 of 205 results for author: Chung, A

Effective Personalized AI Tutors via LLM-Guided Reinforcement Learning

Authors: Angel Tsai-Hsuan Chung, Botong Zhang, Ling-Chieh Kung, Hamsa Bastani, Osbert Bastani

Abstract: Generative AI (GenAI) is rapidly reshaping education by unlocking the potential for personalized tutoring. Yet, emerging platforms largely focus on GenAI chatbot tutors that reactively answer student questions. We hypothesize that the efficacy of GenAI chatbot tutors can be substantially improved by proactively guiding student learning. To test this, we design a novel tutoring platform that tightl… ▽ More Generative AI (GenAI) is rapidly reshaping education by unlocking the potential for personalized tutoring. Yet, emerging platforms largely focus on GenAI chatbot tutors that reactively answer student questions. We hypothesize that the efficacy of GenAI chatbot tutors can be substantially improved by proactively guiding student learning. To test this, we design a novel tutoring platform that tightly integrates a carefully-designed GenAI chatbot with a reinforcement learning algorithm for sequencing practice problems. Critically, this algorithm leverages rich signals from student-chatbot interactions to adaptively select practice problems of an appropriate difficulty level. In partnership with the Taipei City Government and American Institute in Taiwan, we deployed our tutoring platform in conjunction with a five-month course to teach Python to students across ten high schools. We randomized students between a fixed practice problem sequence and our adaptive sequencing algorithm. We find that adaptive sequencing increased unassisted final exam performance by 0.15 standard deviations (equivalent to 6-9 months of schooling by some estimates); mediation analysis suggests that gains were driven by increased engagement. Our work provides large-scale field evidence that student-chatbot interactions provide valuable signals for proactively optimizing and personalizing student learning. △ Less

Submitted 10 July, 2026; originally announced August 2026.

A Naked Dwarf: Molecular Gas in the Completely Stripped HI Tail of VCC 1249

Authors: Bumhyun Lee, Aeree Chung, Paolo Serra, Nikki Zabel, Sungsoon Lim, Hyein Yoon, A. Boselli, Matteo Fossati, Yongjung Kim, Tomonari Michiyama, Juan Molina, Kana Morokuma-Matsui, Jaehyun Lee, Jeong Hwan Lee, Se-Heon Oh

Abstract: We present the first observational hints of the severe removal of both molecular and HI gas from the dwarf galaxy VCC 1249. This extreme stripping event is thought to be driven by the combined effects of tidal interaction and ram pressure. Using deep CO (2$-$1) observations from the James Clerk Maxwell Telescope (JCMT), we obtained marginal CO detections in three regions within the stripped HI tai… ▽ More We present the first observational hints of the severe removal of both molecular and HI gas from the dwarf galaxy VCC 1249. This extreme stripping event is thought to be driven by the combined effects of tidal interaction and ram pressure. Using deep CO (2$-$1) observations from the James Clerk Maxwell Telescope (JCMT), we obtained marginal CO detections in three regions within the stripped HI tail, with molecular masses of $\sim$10$^{5}$ to 10$^{6}$$M_{\odot}$, comparable to typical masses of giant molecular clouds. In contrast, we did not find CO emission within the stellar disk of VCC 1249. This indicates the severe removal of cold gas, which likely caused the sudden cessation of star formation in the galaxy. This identifies VCC 1249 as a unique laboratory for witnessing the rapid, environmentally-driven quenching of a dwarf galaxy. Our findings provide a critical observational link between gas removal mechanisms and the dramatic phase transition of cluster dwarfs from star-forming to quiescent systems. △ Less

Submitted 22 July, 2026; originally announced July 2026.

Comments: 9 pages, 3 figures, 2 tables, accepted for publication in ApJL

Improving Access to Essential Medicines via Decision-Aware Machine Learning

Authors: Angel Tsai-Hsuan Chung, Jatu Abdulai, Patrick Bayoh, Lawrence Sandi, Francis Smart, Hamsa Bastani, Osbert Bastani

Abstract: A critical challenge in healthcare systems in low- and middle-income countries (LMICs) is the efficient and equitable allocation of scarce resources, particularly essential medicines. This problem is complicated by limited high-quality data, which restricts the applicability of traditional data-driven techniques. We propose a novel decision-aware machine learning framework for essential medicines… ▽ More A critical challenge in healthcare systems in low- and middle-income countries (LMICs) is the efficient and equitable allocation of scarce resources, particularly essential medicines. This problem is complicated by limited high-quality data, which restricts the applicability of traditional data-driven techniques. We propose a novel decision-aware machine learning framework for essential medicines allocation, which additionally leverages multi-task learning to ensure sample efficiency and catalytic priors to ensure equitable allocation. In collaboration with the Sierra Leone national government, we performed a staggered, nationwide deployment of our system as a decision support tool. Our econometric evaluation finds an estimated 19% increase in consumption of allocated products in treated districts, demonstrating its efficacy at improving access to essential medicines. Our tool was subsequently scaled nationwide, covering an estimated 2 million women and children under five. Our work demonstrates how machine learning methods can improve efficiency at very low cost in resource-constrained global health settings. △ Less

Submitted 10 July, 2026; originally announced July 2026.

Journal ref: Nature, volume 653, issue 8116, 2026

Anthropogenic disturbance expands the climatic limits of annual plant dominance

Authors: Niv DeMalach, Roberto Salguero-Gomez, Oded Hollander, Jane Lucas, Alexander T. Strauss, Tilak Chaudhary, Y. Anny Chung, James K. McCarthy, Bruno Moreira, Laís Petri, Rachael Thornley, Ingrid J. Slette, Elizabeth T. Borer, Eric W. Seabloom, Joe Atkinson, Karen H. Beard, Lars A. Brudvig, Christopher P. Catano, Jane A. Catford, Aimee Classen, Adam Thomas Clark, Ciara Dwyer, Charles Fenster, Oscar Godoy, Or Gross , et al. (32 additional authors not shown)

Abstract: Disturbance regimes and nutrient inputs are changing worldwide, with consequences for the structure and functioning of plant communities. Classical life-history theory predicts that disturbance should shift communities from long-lived perennials toward short-lived annuals, and that nutrient enrichment may amplify this shift. However, these predictions have not been tested experimentally across bro… ▽ More Disturbance regimes and nutrient inputs are changing worldwide, with consequences for the structure and functioning of plant communities. Classical life-history theory predicts that disturbance should shift communities from long-lived perennials toward short-lived annuals, and that nutrient enrichment may amplify this shift. However, these predictions have not been tested experimentally across broad environmental gradients. Here, using a global coordinated grassland experiment spanning 37 sites, we tested how physical disturbance, vegetation removal and shallow soil tillage, and fertilisation reshape annual-perennial balance, and whether disturbance relaxes the climatic limits of annual dominance. Disturbance nearly doubled the proportion of annual species and more than doubled the relative cover of annuals, whereas fertilisation had little influence and did not interact with disturbance. The disturbance-driven shift arose through contrasting pathways: in graminoids and legumes, it reflected the loss of perennial cover, while in forbs, the expansion of annual cover. In the absence of disturbance, annual dominance was restricted to systems with extremely hot and dry summers, but disturbance nearly tripled the extent of climate space in which annuals dominated. By rapidly reassembling after disturbance, annuals may help maintain vegetation cover, but their expansion also signals loss of perennial cover and the long-term ecosystem functions associated with it. △ Less

Submitted 9 July, 2026; originally announced July 2026.

Modeling Direct Waves in Binary Black Hole Ringdowns

Authors: Richard Dyer, Adrian Ka-Wai Chung, Christopher J. Moore

Abstract: Direct waves, prompt signals propagating from a plunging object to the observer, exist alongside quasinormal modes in binary black hole ringdown. It has been suggested that the properties of the direct wave are related to the event horizon; this simplifies modeling the direct wave and suggests the possibility of using it as a new observational probe of the horizon geometry. This paradigm is tested… ▽ More Direct waves, prompt signals propagating from a plunging object to the observer, exist alongside quasinormal modes in binary black hole ringdown. It has been suggested that the properties of the direct wave are related to the event horizon; this simplifies modeling the direct wave and suggests the possibility of using it as a new observational probe of the horizon geometry. This paradigm is tested by extracting direct waves from numerical-relativity waveforms, adapting techniques originally developed for studying quasinormal modes. The direct wave is identified over a range of ringdown start times, demonstrating the utility of the horizon mode model. However, the direct wave frequency is found to deviate from the horizon value, limiting its utility as a probe of the event horizon. △ Less

Submitted 23 June, 2026; originally announced June 2026.

Comments: 5 pages plus supplemental material, 7 figures

A Universal Physics Defining the Radiation Spectra of Blazars and Gamma-Ray Bursts

Authors: Z. Lucas Uhm, Sang-Sung Lee, Bing Zhang, Judith Racusin, Bindu Rani, Myungshin Im, Aeree Chung, Hyung Mok Lee

Abstract: Blazars and gamma-ray bursts (GRBs) are both cosmic beacons of extreme energy release powered by relativistic jets. However, they originate from tremendously different environments. Blazars are the sustained powerhouses driven by supermassive black holes at galactic centers, whereas GRBs are the transient death signals of massive stars or merging compact objects. Here we show that, despite the eno… ▽ More Blazars and gamma-ray bursts (GRBs) are both cosmic beacons of extreme energy release powered by relativistic jets. However, they originate from tremendously different environments. Blazars are the sustained powerhouses driven by supermassive black holes at galactic centers, whereas GRBs are the transient death signals of massive stars or merging compact objects. Here we show that, despite the enormous differences, a universal physics defines the radiation spectra of blazars and GRBs. The blazar spectrum is well described by a "log-parabola" function. Employing a simple toy model with a single optically-thin region of a decreasing magnetic field, we produce the log-parabola spectrum very naturally for blazars. We find that the blazar spectrum is shaped by the "cooling physics" of relativistic electrons in the fast-cooling regime, which we identify as the universal physics since we previously showed that the fast-cooling physics of electrons with a decreasing magnetic field also explains the mysterious low-energy spectral index of the gamma-ray spectrum for a majority of GRBs. This fast-cooling physics of electrons likely nails down the physical origin underlying the universal scaling of the jet energetics between blazars and GRBs, which was observationally suggested more than a decade ago. We highlight that the spectrum shaper in both blazars and GRBs is the cooling physics, not the acceleration mechanism. This finding is conventional-belief-defying and may open up new avenues in a wide range of astrophysics. △ Less

Submitted 14 June, 2026; originally announced June 2026.

Comments: ApJ published, 9 pages, 4 figures, 1 table

Measuring a Black Hole's Area Immediately after Merger: A Direct-Wave Test of Hawking's Area Law

Authors: Adrian Ka-Wai Chung, Kelvin Ka-Ho Lam, Anna Liu, Nicolas Yunes

Abstract: Black-hole area is the geometric variable behind horizon thermodynamics. We introduce a gravitational-wave method to infer a Kerr-equivalent horizon area from direct waves in the near-merger signal, before quasinormal ringing dominates at late times. Applied to GW250114, and interpreting the fitted direct-wave frequency and damping rate as horizon quantities, we find that analyses initiated $3$--… ▽ More Black-hole area is the geometric variable behind horizon thermodynamics. We introduce a gravitational-wave method to infer a Kerr-equivalent horizon area from direct waves in the near-merger signal, before quasinormal ringing dominates at late times. Applied to GW250114, and interpreting the fitted direct-wave frequency and damping rate as horizon quantities, we find that analyses initiated $3$--$4.5M$ before the peak-amplitude time yield an area consistent with the Kerr remnant. This result gives a first area measurement using direct waves and a new near-merger test of Hawking's area law. △ Less

Submitted 4 June, 2026; originally announced June 2026.

Comments: 5 pages of main text (with 3 figures), 2 pages of End Matter (with 1 figure)

Report number: LIGO PNP P2600278

MINDGAMES: A Live Arena for Evaluating Social and Strategic Reasoning in Multi-Agent LLMs

Authors: Kevin Wang, Anna Thöni, Benjamin Kempinski, Bobby Cheng, Jianzhu Yao, Benjamin Finch, Leon Guertler, Viraj Nadkarni, Yihan Jiang, Aliaksei Korshuk, Alexander Buyantuev, Ilya Makarov, Siyuan Wu, Yu-Chi Cheng, Yan-Ru Ju, Ti-Rong Wu, I-Hsuan Chu, Yu-Yu Yang, I-Chen Wu, Yitian Huang, Qinlu Cao, Yiheng Sun, Yuhong Dai, Hongkun Yao, Jingxuan Fu , et al. (28 additional authors not shown)

Abstract: Large language models (LLMs) are increasingly deployed as interactive agents, yet their capacity for social and strategic reasoning over extended interaction remains poorly understood. Existing evaluations rely on static vignettes or single-game benchmarks that cannot capture the sustained, multi-faceted reasoning that real-world multi-agent settings demand. We introduce Mindgames, a multi-game ar… ▽ More Large language models (LLMs) are increasingly deployed as interactive agents, yet their capacity for social and strategic reasoning over extended interaction remains poorly understood. Existing evaluations rely on static vignettes or single-game benchmarks that cannot capture the sustained, multi-faceted reasoning that real-world multi-agent settings demand. We introduce Mindgames, a multi-game arena and evaluation platform for LLM agents that operationalizes complementary reasoning demands relevant to ``theory of mind'': belief attribution under hidden information, opponent modeling through repeated strategic interaction, cooperative inference under knowledge asymmetries, and sustained deception in social deduction. Built on TextArena, Mindgames provides a unified interaction interface, TrueSkill-based rating, and full trajectory logging across four game environments. We instantiate Mindgames through a 2025 competition cycle hosted at a major AI conference, which assessed 944 submitted agents from 76 teams across four games: Colonel Blotto, Iterated Prisoner's Dilemma, Codenames, and Secret Mafia. Our analysis surfaces both agent-level and evaluation-level limitations: brittle rule adherence remains a major bottleneck, top-performing systems repeatedly rely on explicit structural scaffolding, and leaderboard validity differs sharply across environments. In particular, failure-heavy environments can reward robustness to opponent errors as much as strategic ability, with Secret Mafia exhibiting a pronounced error-survival confound in this cycle. We release a dataset of 29,571 multi-agent games with turn-level observations, actions, and rewards, together with MG-Ref, a deterministic offline tournament protocol that scores new agents against a frozen reference pool of top-ranked, low-error Stage~II submissions under the same error-attribution lens used in this analysis. △ Less

Submitted 28 May, 2026; originally announced May 2026.

MAUVE-MUSE: Ionization and Kinematic Signatures of Environmental Effects on Virgo Cluster Disks

Authors: Toby Brown, Luca Cortese, Barbara Catinella, A. Fraser-McKelvie, Adam B. Watts, Amirnezam Amiri, Alessandro Boselli, Woorak Choi, Aeree Chung, Timothy A. Davis, Eric Emsellem, Pavel Jáchym, María J. Jiménez-Donaire, Tutku Kolcu, Bumhyun Lee, Andrei Ristea, Jesse van de Sande, Kristine Spekkens, Sabine Thater, Christine D. Wilson, Nikki Zabel

Abstract: We present early science results from the MAUVE (Multiphase Astrophysics to Unveil the Virgo Environment) program which targets 40 Virgo Cluster galaxies to investigate the effect of environment on the interstellar medium (ISM) at ~100 pc scales. From 12 galaxies in the MAUVE-MUSE early sample, we find systematically elevated line ratios compared to PHANGS-MUSE field disks, with higher medians of… ▽ More We present early science results from the MAUVE (Multiphase Astrophysics to Unveil the Virgo Environment) program which targets 40 Virgo Cluster galaxies to investigate the effect of environment on the interstellar medium (ISM) at ~100 pc scales. From 12 galaxies in the MAUVE-MUSE early sample, we find systematically elevated line ratios compared to PHANGS-MUSE field disks, with higher medians of [N II]/H$α$ (0.75 vs. 0.50), [S II]/H$α$ (0.57 vs. 0.49), and [O III]/H$β$ (1.04 vs. 0.68). Spatially resolved BPT diagrams show 74% of MAUVE-MUSE spaxels ionized by sources other than H II regions, versus 61% in the field, and we find these ionization differences to be closely coupled to broadened kinematics. 44% of MAUVE-MUSE spaxels exceed H$α$ $σ_{LOS} = 40$ km/s (vs. 26% in the field), driven mainly by non-star-forming gas with $σ_{LOS}$ between 40 and 80 km/s, consistent with enhanced contribution of diffuse ionized gas (DIG). A subdominant tail of 5% of spaxels at $σ_{LOS} > 100$ km/s, largely absent in PHANGS-MUSE (1%), points to shocks or turbulent mixing layers from intracluster interactions. Our results show that environmental quenching primarily suppresses star formation, unveiling DIG as the dominant ionized component in cluster disks. The elevated line ratios and broadened kinematics observed in the MAUVE sample reflect the physical state of the ISM in the absence of vigorous star formation, rather than widespread direct environmental excitation. The observed shock-like emission provides an additional, secondary contribution likely driven by active interactions with the intracluster medium. △ Less

Submitted 21 April, 2026; originally announced April 2026.

Comments: 17 pages, 11 figures + appendices, accepted for publication in ApJ

Quadratic gravity corrections to scalar QNMs of rapidly rotating black holes

Authors: Stef J. B. Husken, Tom van der Steen, Simon Maenaut, Kelvin Ka-Ho Lam, Maxim D. Jockwer, Adrian Ka-Wai Chung, Thomas Hertog, Tjonnie G. F. Li, Nicolás Yunes

Abstract: In an effective-field-theory framework for gravity, black-hole quasinormal mode spectra acquire corrections in quadratic-curvature, scalar-tensor extensions of general relativity. Previous calculations of such corrections were limited to moderate spins, since the corresponding background solutions relied on expansions in the spin parameter. Using recently constructed numerical black-hole solutions… ▽ More In an effective-field-theory framework for gravity, black-hole quasinormal mode spectra acquire corrections in quadratic-curvature, scalar-tensor extensions of general relativity. Previous calculations of such corrections were limited to moderate spins, since the corresponding background solutions relied on expansions in the spin parameter. Using recently constructed numerical black-hole solutions valid for large spin, we compute the leading-order deviations from general relativity in the scalar quasinormal mode spectrum of rotating black holes in scalar Gauss-Bonnet and dynamical Chern-Simons gravity. We solve the resulting perturbation equations with pseudo-spectral collocation methods, allowing us to determine the quasinormal-mode corrections for dimensionless spins up to $a/M=0.99$, with accuracy better than $\lesssim 10^{-3}$ for the $l=m=0$ mode and $\lesssim 10^{-6}$ for higher multipoles. For spins $a/M>0.9$, the corrections to certain modes can increase by orders of magnitude. △ Less

Submitted 14 April, 2026; v1 submitted 2 April, 2026; originally announced April 2026.

Comments: 13 pages, 5 figures; minor technical corrections to references and appendix

BASS. LI. Cool gas supply of HI-massive local Seyfert galaxies

Authors: Jeein Kim, Aeree Chung, O. Ivy Wong, Junhyun Baek, Chandrashekar Murugeshan, Michael J. Koss, Kyuseok Oh, Franz Erik Bauer, Chin-Shin Chang, Yaherlyn Diaz, Kohei Ichikawa, Darshan Kakkad, Minjin Kim, Macon Magno, Ignacio del Moral-Castro, Richard Mushotzky, Alessandro Peca, Claudio Ricci, Matilde Signorini, Miguel Parra Tello, Benny Trakhtenbrot, Jong-Hak Woo

Abstract: We present neutral atomic hydrogen (HI) imaging observations of 22 HI-rich ($M_{\rm HI} \gtrsim 10^{9.7} M_\odot$), hard X-ray-selected local Seyferts to explore how cool gas is supplied to active galactic nuclei (AGN) hosts. The sample predominantly resides in group-like, gas-rich environments. About 80% (18/22) of the galaxies have HI-detected neighbors, 61% (11/18) of which clearly exhibit stro… ▽ More We present neutral atomic hydrogen (HI) imaging observations of 22 HI-rich ($M_{\rm HI} \gtrsim 10^{9.7} M_\odot$), hard X-ray-selected local Seyferts to explore how cool gas is supplied to active galactic nuclei (AGN) hosts. The sample predominantly resides in group-like, gas-rich environments. About 80% (18/22) of the galaxies have HI-detected neighbors, 61% (11/18) of which clearly exhibit strong lopsidedness, one-sided gas tails, and/or gas structures connecting to nearby companion galaxies, suggesting gas exchange histories. We examine the HI size-mass relation and star formation properties of these HI-rich AGN hosts, finding no systematic deviations from known scaling relations. In most cases, our samples are the most massive systems within their respective groups, implying that our sample is more likely to acquire gas rather than lose it. Interestingly, galaxies with more extended HI disks show stronger AGN activity. Considering that extended HI is often associated with external processes, this finding suggests that environmentally accreted gas - through galaxy interactions and gas exchange with neighboring systems - may have played a role in supplying additional fuel to the AGNs in our sample. Notably, the HI extent-AGN activity correlation becomes even tighter for those AGN hosts whose neighboring galaxies are gas poor or lack HI, further supporting externally supplied gas as a fuel source. △ Less

Submitted 16 March, 2026; originally announced March 2026.

Comments: 19 pages, 3 tables, 6+7 figures, accepted for publication in A&A

MBD: A Model-Based Debiasing Framework Across User, Content, and Model Dimensions

Authors: Yuantong Li, Lei Yuan, Zhihao Zheng, Weimiao Wu, Songbin Liu, Jeong Min Lee, Ali Selman Aydin, Shaofeng Deng, Junbo Chen, Xinyi Zhang, Hongjing Xia, Sam Fieldman, Matthew Kosko, Wei Fu, Du Zhang, Peiyu Yang, Albert Jin Chung, Xianlei Qiu, Miao Yu, Zhongwei Teng, Hao Chen, Sunny Baek, Hui Tang, Yang Lv, Renze Wang , et al. (5 additional authors not shown)

Abstract: Modern recommendation systems rank candidates by aggregating multiple behavioral signals through a value model. However, many commonly used signals are inherently affected by heterogeneous biases. For example, watch time naturally favors long-form content, loop rate favors short - form content, and comment probability favors videos over images. Such biases introduce two critical issues: (1) value… ▽ More Modern recommendation systems rank candidates by aggregating multiple behavioral signals through a value model. However, many commonly used signals are inherently affected by heterogeneous biases. For example, watch time naturally favors long-form content, loop rate favors short - form content, and comment probability favors videos over images. Such biases introduce two critical issues: (1) value model scores may be systematically misaligned with users' relative preferences - for instance, a seemingly low absolute like probability may represent exceptionally strong interest for a user who rarely engages; and (2) changes in value modeling rules can trigger abrupt and undesirable ecosystem shifts. In this work, we ask a fundamental question: can biased behavioral signals be systematically transformed into unbiased signals, under a user - defined notion of ``unbiasedness'', that are both personalized and adaptive? We propose a general, model-based debiasing (MBD) framework that addresses this challenge by augmenting it with distributional modeling. By conditioning on a flexible subset of features (partial feature set), we explicitly estimate the contextual mean and variance of the engagement distribution for arbitrary cohorts (e.g., specific video lengths or user regions) directly alongside the main prediction. This integration allows the framework to convert biased raw signals into unbiased representations, enabling the construction of higher-level, calibrated signals (such as percentiles or z - scores) suitable for the value model. Importantly, the definition of unbiasedness is flexible and controllable, allowing the system to adapt to different personalization objectives and modeling preferences. Crucially, this is implemented as a lightweight, built-in branch of the existing MTML ranking model, requiring no separate serving infrastructure. △ Less

Submitted 15 March, 2026; originally announced March 2026.

Spacetime of rotating black holes surrounded by massive scalar charges

Authors: Adrian Ka-Wai Chung

Abstract: Massive scalar charges are ubiquitous in extensions to General Relativity and the Standard Model in particle physics. We describe spectral methods which can accurately construct the spacetime of rotating black holes with dimensionless spin up to $a \leq 0.8$ surrounded by massive scalar fields nonminimally coupled to spacetime curvature. We consider axi dilaton, dynamical Chern Simons, and scalar… ▽ More Massive scalar charges are ubiquitous in extensions to General Relativity and the Standard Model in particle physics. We describe spectral methods which can accurately construct the spacetime of rotating black holes with dimensionless spin up to $a \leq 0.8$ surrounded by massive scalar fields nonminimally coupled to spacetime curvature. We consider axi dilaton, dynamical Chern Simons, and scalar Gauss Bonnet couplings, and obtain leading order solutions for both the scalar field and the associated metric modifications. Our method accurately resolves massive scalar fields with Compton wavelengths as short as 5 times the black hole mass, achieving residual errors $\lesssim 10^{-5}$, and yields the corresponding leading order spacetime modifications with residual errors $\lesssim 10^{-3}$. Using the constructed spacetimes, we computes the leading-order shifts in the surface gravity and the angular velocity of the event horizon, important information for computing the quasinormal modes. These results pave the way to incorporate massive scalar charges into electromagnetic observations and gravitational-wave detections of black holes, potentially enabling new probes of fundamental scalar degrees of freedom. △ Less

Submitted 31 May, 2026; v1 submitted 10 February, 2026; originally announced February 2026.

Comments: 21 pages of main text, 13 figures; Match the published version; Data product available at https://zenodo.org/records/20022233

Journal ref: Phys. Rev. D 113, 095032 (2026)

CHILES XI: Resolved HI morphologies and the evolution of the H2/HI ratio over the last five billion years

Authors: J. Blue Bird, N. Luber, H. B. Gim, J. H. van Gorkom, D. J. Pisano, Min S. Yun, E. Momjian, K. M. Hess, D. Lucero, J. Donovan Meyer, A. Chung

Abstract: We present the neutral gas morphology of four galaxies from z = 0.22 to 0.47 obtained with the COSMOS HI Large Extragalactic Survey (CHILES). The HI is resolved at the highest redshift with the 7.5 arcsec beam of CHILES and 43 kpc linear scale, with all four galaxies having extended HI. Three are massive galaxies (Mstellar > 3 e10 Mo), with HI masses of 1.6 - 6.7 e10 Mo, and active star formation… ▽ More We present the neutral gas morphology of four galaxies from z = 0.22 to 0.47 obtained with the COSMOS HI Large Extragalactic Survey (CHILES). The HI is resolved at the highest redshift with the 7.5 arcsec beam of CHILES and 43 kpc linear scale, with all four galaxies having extended HI. Three are massive galaxies (Mstellar > 3 e10 Mo), with HI masses of 1.6 - 6.7 e10 Mo, and active star formation (3 - 30 Mo/yr). The morphology and kinematics of the galaxies vary from regular to disturbed, including an asymmetric HI disk surrounding the fourth smaller galaxy (Mstellar ~ e9 Mo). CO(1-0) observations of the sample, obtained with the LMT, confirm the redshifts of three of the four galaxies and we derive H2 masses of 0.4 - 5.2 e10 Mo. JWST imaging with four combined NIRCam filters reveals disturbed stellar components with compact knots in two of the galaxies. We combine our new higher-redshift galaxies with previously published observations to conduct a more complete study of HI and H2 evolution in the redshift range 0 - 0.5. With our HI flux-limited observations compared to similar lower redshift galaxies with high stellar mass (Mstellar > e10 Mo), the results show the mean H2/HI ratio at the highest redshift is 10.3 +- 3.4 larger than the mean H2/HI ratio in the local Universe. △ Less

Submitted 16 January, 2026; originally announced January 2026.

The impact of ram pressure on the radio spectral index and magnetic field of NGC 4522: A high-resolution VLA continuum study

Authors: Woorak Choi, Aeree Chung, Chang-Goo Kim, Bumhyun Lee, Luca Cortese, Toby Brown, Barbara Catinella, Eric Emsellem, A. Fraser-McKelvie, Jiayi Sun, Adam Watts

Abstract: We present high-resolution Very Large Array (VLA) continuum observations at S-band ($3$ GHz, $560$ pc scale) and X-band ($10$ GHz, $200$ pc scale) of the ram-pressure-stripped Virgo galaxy NGC 4522, to investigate the characteristics of its radio continuum, spectral index, and magnetic field under the influence of the intracluster medium (ICM). The total radio continuum shows an asymmetry that ext… ▽ More We present high-resolution Very Large Array (VLA) continuum observations at S-band ($3$ GHz, $560$ pc scale) and X-band ($10$ GHz, $200$ pc scale) of the ram-pressure-stripped Virgo galaxy NGC 4522, to investigate the characteristics of its radio continuum, spectral index, and magnetic field under the influence of the intracluster medium (ICM). The total radio continuum shows an asymmetry that extends northwest, mirroring the HI gas distribution, but showing distinct features in the extraplanar regions. The spectral index steepens systematically from $α\sim-0.6$ in the main disk to $α\sim-1.1$ in the outer disk. We find that the spectral index behavior of the outer disk is mainly due to an ICM shock that can re-accelerate electrons and a significant reduction of thermal emission. Intriguingly, extraplanar clouds exhibit exceptionally flat spectral indices ($α\sim-0.2$ to $0$), resulting from a combination of significantly enhanced thermal emission and pronounced spectral aging of the non-thermal component. Although some of these regions correlate with H$α$, others do not. We propose that the mixing between the ICM and interstellar medium (ISM) is an alternative mechanism that enhances thermal emission independently of star formation. Polarized continuum emissions are highly asymmetric, preferentially distributed along the ICM wind side, and the polarization fraction increases radially outward from the galactic midplane, indicating that the polarized emission is strongly influenced by the ICM wind. Our results show how and where the ICM substantially affects the ISM, and also demonstrate that high-frequency observations are crucial for analyzing the radio continuum of ram pressure stripping galaxies. △ Less

Submitted 15 January, 2026; originally announced January 2026.

Comments: 25 pages, 12 figures, Accepted for publication in ApJ

More than Segmentation: Benchmarking SAM 3 for Segmentation, 3D Perception, and Reconstruction in Robotic Surgery

Authors: Wenzhen Dong, Jieming Yu, Yiming Huang, Hongqiu Wang, Lei Zhu, Albert C. S. Chung, Hongliang Ren, Long Bai

Abstract: The recent SAM 3 and SAM 3D have introduced significant advancements over the predecessor, SAM 2, particularly with the integration of language-based segmentation and enhanced 3D perception capabilities. SAM 3 supports zero-shot segmentation across a wide range of prompts, including point, bounding box, and language-based prompts, allowing for more flexible and intuitive interactions with the mode… ▽ More The recent SAM 3 and SAM 3D have introduced significant advancements over the predecessor, SAM 2, particularly with the integration of language-based segmentation and enhanced 3D perception capabilities. SAM 3 supports zero-shot segmentation across a wide range of prompts, including point, bounding box, and language-based prompts, allowing for more flexible and intuitive interactions with the model. In this empirical evaluation, we assess the performance of SAM 3 in robot-assisted surgery, benchmarking its zero-shot segmentation with point and bounding box prompts and exploring its effectiveness in dynamic video tracking, alongside its newly introduced language prompt segmentation. While language prompts show potential, their performance in the surgical domain is currently suboptimal, highlighting the need for further domain-specific training. Additionally, we investigate SAM 3D's depth reconstruction abilities, demonstrating its capacity to process surgical scene data and reconstruct 3D anatomical structures from 2D images. Through comprehensive testing on the MICCAI EndoVis 2017 and EndoVis 2018 benchmarks, SAM 3 shows clear improvements over SAM and SAM 2 in both image and video segmentation under spatial prompts, while the zero-shot evaluations of SAM 3D on SCARED, StereoMIS, and EndoNeRF indicate strong monocular depth estimation and realistic 3D instrument reconstruction, yet also reveal remaining limitations in complex, highly dynamic surgical scenes. △ Less

Submitted 10 December, 2025; v1 submitted 8 December, 2025; originally announced December 2025.

Comments: Technical Report

The MALATANG survey: star formation, dense gas, and AGN feedback in NGC 1068

Authors: Shuting Lin, Siyi Feng, Zhi-Yu Zhang, Chunyi Zhang, Qing-Hua Tan, Junzhi Wang, Yu Gao, Xue-Jian Jiang, Yang Gao, Xiao-Long Wang, Junfeng Wang, Jian-Fa Wang, Satoki Matsushita, Aeree Chung, Kotaro Kohno, Tosaki Tomoka, Thomas R. Greve

Abstract: We aim to investigate the interplay between dense molecular gas, star formation, and active galactic nucleus (AGN) feedback in the luminous infrared galaxy (LIRG) NGC 1068 at sub-kiloparsec scales. We present the HCN (4-3) and HCO$^+$ (4-3) maps of NGC 1068, obtained with JCMT as part of the Mapping the dense molecular gas in the strongest star-forming galaxies (MALATANG) project, and perform spat… ▽ More We aim to investigate the interplay between dense molecular gas, star formation, and active galactic nucleus (AGN) feedback in the luminous infrared galaxy (LIRG) NGC 1068 at sub-kiloparsec scales. We present the HCN (4-3) and HCO$^+$ (4-3) maps of NGC 1068, obtained with JCMT as part of the Mapping the dense molecular gas in the strongest star-forming galaxies (MALATANG) project, and perform spatially resolved analyses of their correlations with infrared luminosity and soft X-ray emission. Spatially resolved relations between the luminosities of infrared dust emission and dense molecular gas tracers ($L_{\rm IR}-L'_{\rm dense}$) are found to be nearly linear, without clear evidence of excess contributions from AGN activity. The spatially resolved X-ray emission ($L^{\rm gas}_{0.5-2\,\mathrm{keV}}$) displays a radially-dependent twofold correlation with the star formation rate (SFR), suggesting distinct gas-heating mechanisms between the galaxy center and the outer regions. A super-linear scaling is obtained in galactic center regions with SFR surface density ($Σ_{\rm SFR}$) $>$ 8.2 $\times$ 10$^{-6}$ $M_\odot$ yr$^{-1}$ kpc$^{-2}$: log($L^{\rm gas}_{0.5-2\,\mathrm{keV}}$/erg s$^{-1}$) = 2.2 log(SFR/$M_\odot$ yr$^{-1}$) + 39.1. We further found a statistically significant super-linear correlation ($β= 1.34$ $\pm$ 0.86) between $L^{\rm gas}_{0.5-2\,\mathrm{keV}}$/SFR and HCN(4-3)/CO(1-0) intensity ratio, whereas no such trend is seen for HCO$^+$(4-3)/CO(1-0) or CO(3-2)/CO(1-0). These findings indicate that AGN feedback does not dominate star formation regulation on sub-kiloparsec scales, and that the excitation of dense gas traced by HCN (4-3) may be more directly influenced by high-energy feedback processes compared to HCO$^+$ (4-3) and CO (3-2). △ Less

Submitted 4 December, 2025; originally announced December 2025.

Comments: 12 pages, 7 figures. Accepted for publication in A&A

Journal ref: A&A 707, A20 (2026)

Evaluating Long-Context Reasoning in LLM-Based WebAgents

Authors: Andy Chung, Yichi Zhang, Kaixiang Lin, Aditya Rawal, Qiaozi Gao, Joyce Chai

Abstract: As large language model (LLM)-based agents become increasingly integrated into daily digital interactions, their ability to reason across long interaction histories becomes crucial for providing personalized and contextually aware assistance. However, the performance of these agents in long context scenarios, particularly for action-taking WebAgents operating in realistic web environments, remains… ▽ More As large language model (LLM)-based agents become increasingly integrated into daily digital interactions, their ability to reason across long interaction histories becomes crucial for providing personalized and contextually aware assistance. However, the performance of these agents in long context scenarios, particularly for action-taking WebAgents operating in realistic web environments, remains largely unexplored. This paper introduces a benchmark for evaluating long context reasoning capabilities of WebAgents through sequentially dependent subtasks that require retrieval and application of information from extended interaction histories. We develop a novel evaluation framework that simulates multi-session user interactions by injecting irrelevant task trajectories between dependent subtasks, creating contexts ranging from 25,000 to 150,000 tokens. Through extensive evaluation of four popular models, Claude-3.7, GPT-4.1, Llama 4, and o4-mini, we observe a dramatic performance degradation as context length increases, with success rates dropping from 40-50\% in baseline conditions to less than 10\% in long context scenarios. Our detailed error analysis reveals that agents primarily fail due to getting stuck in loops and losing track of original task objectives. We further propose an implicit RAG approach that provides modest improvements by generating task-relevant summaries, though fundamental limitations in long context reasoning persist. These findings highlight critical challenges for deploying WebAgents in realistic, long-term user interaction scenarios and provide insights for developing more robust agent architectures capable of maintaining coherent task execution across extended contexts. △ Less

Submitted 3 December, 2025; originally announced December 2025.

Comments: Accepted NeurIPS 25 LAW Workshop

Multiphase Astrophysics to Unveil the Virgo Environment (MAUVE)

Authors: Barbara Catinella, Luca Cortese, Jiayi Sun, Toby Brown, Eric Emsellem, Amelia Fraser-McKelvie, Adam B. Watts, Amy Attwater, Andrew Battisti, Alessandro Boselli, Woorak Choi, Aeree Chung, Elisabete da Cunha, Timothy A. Davis, Sara Ellison, Pavel Jáchym, Maria J. Jimenez-Donaire, Tutku Kolcu, Bumhyun Lee, James McGregor, Ian Roberts, Eva Schinnerer, Kristine Spekkens, Sabine Thater, David Thilker , et al. (4 additional authors not shown)

Abstract: The Multiphase Astrophysics to Unveil the Virgo Environment (MAUVE) project is a multi-facility programme exploring how dense environments transform galaxies. Combining a VLT/MUSE P110 Large Programme and ALMA observations of 40 late-type Virgo Cluster galaxies, MAUVE resolves star formation, kinematics, and chemical enrichment within their molecular gas discs. A key goal is to track the evolution… ▽ More The Multiphase Astrophysics to Unveil the Virgo Environment (MAUVE) project is a multi-facility programme exploring how dense environments transform galaxies. Combining a VLT/MUSE P110 Large Programme and ALMA observations of 40 late-type Virgo Cluster galaxies, MAUVE resolves star formation, kinematics, and chemical enrichment within their molecular gas discs. A key goal is to track the evolution of cold gas that survives in the inner regions of satellites after entering the cluster, and how it evolves across different infall stages. With its high spatial resolution -- probing down to the physical scales of giant molecular cloud complexes -- and multiphase synergy, MAUVE aims to offer a time-resolved view of environmental quenching and set a new benchmark for cluster galaxy studies. △ Less

Submitted 21 November, 2025; originally announced November 2025.

Comments: 4 pages, 3 figures. Published in the ESO Messenger 195

Journal ref: The Messenger, 2025, Vol. 195, pages 15-18

CHILES X: Molecular and atomic gas at intermediate redshift

Authors: Kelley M. Hess, John Hibbard, Jennifer Donovan Meyer, Hansung B. Gim, Nicholas M. Luber, Min S. Yun, Julia Blue Bird, Richard Dodson, Aeree Chung, Danielle Lucero, Emmanuel Momjian, D. J. Pisano, J. H. van Gorkom

Abstract: We present ALMA CO observations of 14 HI-detected galaxies from the CHILES survey found in a cosmic over-density at z~0.12. This is the largest collection of spatially resolved CO + HI observations beyond the local Universe (z>0.05) to date. While the HI-detected parent sample spans a range of stellar masses, star formation rates (SFR), and environments, we only directly detect CO in the highest s… ▽ More We present ALMA CO observations of 14 HI-detected galaxies from the CHILES survey found in a cosmic over-density at z~0.12. This is the largest collection of spatially resolved CO + HI observations beyond the local Universe (z>0.05) to date. While the HI-detected parent sample spans a range of stellar masses, star formation rates (SFR), and environments, we only directly detect CO in the highest stellar mass galaxies, log(M_*/M_Sun)>10.0, with SFRs greater than ~2 M_Sun/yr. The detected CO has the kinematic signature of a rotating disk, consistent with the HI. We stack the CO non-detections and find a mean H_2 mass of log(M_H2/M_Sun) = 8.46 in galaxies with a mean stellar mass of log(M_*/M_Sun) = 9.35. In addition to high stellar masses and SFRs, the systems detected in CO are spatially larger, have redder overall colors, and exhibit broader (stacked) line widths. The CO emission is spatially coincident with both the highest stellar mass surface density and star forming region of the galaxies, as revealed by the 1.4 GHz continuum emission. We interpret the redder colors as the molecular gas being coincident with dusty regions of obscured star formation. The 14 HI detections show a range of morphologies, but the HI reservoir is always more extended than the CO. Finally, we compare with samples in the literature and find mild evidence for evolution in the molecular gas reservoir and H_2-to-HI gas ratio with redshift in HI flux-limited samples. We show that the scatter in the HI, and HI-to-stellar mass ratio is too great to conclusively measure evolution below z=0.2, and is even extremely difficult below z=0.4. Detections from CHILES are likely to be the only individual galaxies detected in HI between 0.1<z<0.23 for the foreseeable future due to the severity of satellite radio frequency interference, and its preferential impact on short baselines which dominate contemporary HI surveys. △ Less

Submitted 16 October, 2025; v1 submitted 9 October, 2025; originally announced October 2025.

Comments: Accepted for publication in A&A. Abstract abridged for the arxiv submission

Journal ref: A&A 705, A163 (2026)

Analytic and accurate approximate metrics for black holes with arbitrary rotation in beyond-Einstein gravity using spectral methods

Authors: Kelvin Ka-Ho Lam, Adrian Ka-Wai Chung, Nicolás Yunes

Abstract: A key obstacle for theory-specific tests of general relativity is the lack of accurate black-hole solutions in beyond-Einstein theories, especially for moderate to high spins. We address this by developing a general framework--based on spectral and pseudospectral methods--to obtain analytic, closed-form spacetimes representing stationary, axisymmetric black holes in effective-field-theory extensio… ▽ More A key obstacle for theory-specific tests of general relativity is the lack of accurate black-hole solutions in beyond-Einstein theories, especially for moderate to high spins. We address this by developing a general framework--based on spectral and pseudospectral methods--to obtain analytic, closed-form spacetimes representing stationary, axisymmetric black holes in effective-field-theory extensions of general relativity to leading order in the coupling constants. The approach models the spacetime (and extra fields) as a stationary, axisymmetric deformation of the Kerr metric in Boyer-Lindquist-like coordinates, expands metric deformations as a spectral series in radius and polar angle, and converts the resulting beyond-Einstein field equations into algebraic equations for the spectral coefficients. For any given spin, these equations are solved via standard linear-algebra methods; the coefficients are then fitted as functions of spin with non-linear functions, yielding fully analytic metrics for rotating black holes in beyond-Einstein theories. We apply this to quadratic gravity theories--dynamical Chern-Simons, scalar-Gauss-Bonnet, and axi-dilaton gravity--obtaining solutions valid for any spin, including near-extremal cases with errors below machine precision for $a \leq 0.9$ and $\lesssim 10^{-8}$ for $a \leq 0.999$. We show that existing slowly-rotating solutions break down at $a \sim (0.2, 0.6)$, depending on approximation order and chosen accuracy. We then use our metrics to compute observables, such as the surface gravity, horizon angular velocity, and the locations of the innermost circular orbit and the photon ring. The framework is general and applicable to other effective-field-theory extensions for black holes of any spin. △ Less

Submitted 15 January, 2026; v1 submitted 6 October, 2025; originally announced October 2025.

Comments: 26 pages, 16 figures; matches published version

Journal ref: Phys. Rev. D 113, 024030 (2026)

Spinning Black Holes in Modified Gravity via Spectral Methods

Authors: Kelvin Ka-Ho Lam, Adrian Ka-Wai Chung, Nicolás Yunes

Abstract: Rapidly-rotating black-hole spacetimes outside general relativity are key to many tests of Einstein's theory. We here develop an efficient spectral method to represent such spacetimes analytically, in closed-form, and to high accuracy, in a large class of effective-field-theory extensions of general relativity. We exemplify this method by constructing, for the first time, closed-form and analytic… ▽ More Rapidly-rotating black-hole spacetimes outside general relativity are key to many tests of Einstein's theory. We here develop an efficient spectral method to represent such spacetimes analytically, in closed-form, and to high accuracy, in a large class of effective-field-theory extensions of general relativity. We exemplify this method by constructing, for the first time, closed-form and analytic representations of spinning black holes in scalar-Gauss-Bonnet, dynamical Chern-Simons, and axidilaton gravity to an accuracy better than $10^{-8}$ for all dimensionless spins below 0.99. △ Less

Submitted 18 January, 2026; v1 submitted 8 September, 2025; originally announced September 2025.

Comments: 5 pages of main text, 2 figures; matches published version

Journal ref: Phys. Rev. Lett. 136, 021401 (2026)

High-Distance Error-Correcting Codes for Fermion-to-Qubit Mappings in 2D and 3D

Authors: Ruby Wei, Aqua Chung, Luke Coffman, Su-Kuan Chu, Xun Gao

Abstract: Quantum simulation of fermionic systems is a leading application of quantum computers. One promising approach is to represent fermions with qubits via fermion-to-qubit mappings. In this work, we present high-distance fermion-to-qubit stabilizer codes for simulating 2D and 3D fermionic systems. These codes achieve arbitrarily large code distances while keeping stabilizer weights constant. They also… ▽ More Quantum simulation of fermionic systems is a leading application of quantum computers. One promising approach is to represent fermions with qubits via fermion-to-qubit mappings. In this work, we present high-distance fermion-to-qubit stabilizer codes for simulating 2D and 3D fermionic systems. These codes achieve arbitrarily large code distances while keeping stabilizer weights constant. They also preserve locality by mapping local fermionic operators to local qubit operators at any fixed distance. Notably, our 3D construction is the first to simultaneously achieve high distance, constant stabilizer weights, and locality preservation. Our construction is based on concatenating a small-distance 2D or 3D fermion-to-qubit code with a high-distance fermionic color code. Together, these features provide a robust and scalable pathway to quantum simulation of fermionic systems. △ Less

Submitted 29 August, 2025; originally announced September 2025.

Comments: 18 pages, 8 figures

VERTICO IX: Signatures of environmental processing of the gas in Virgo cluster spiral galaxies through mapping of CO isotopologues

Authors: Timothy A. Davis, Toby Brown, Maria J. Jimenez-Donaire, Christine D. Wilson, Dhruv Bisaria, Alessandro Boselli, Barbara Catinella, Aeree Chung, Luca Cortese, Sara Ellison, Bumhyun Lee, Ian D. Roberts, Kristine Spekkens, Vicente Villanueva, Nikki Zabel

Abstract: In this work we study CO isotopologue emission in the largest cluster galaxy sample to date: 48 VERTICO spiral galaxies in Virgo. We show for the first time in a significant sample that the physical conditions within the molecular gas appear to change as a galaxy's ISM is affected by environmental processes. 13CO is detected across the sample, both directly and via stacking, while C18O is detected… ▽ More In this work we study CO isotopologue emission in the largest cluster galaxy sample to date: 48 VERTICO spiral galaxies in Virgo. We show for the first time in a significant sample that the physical conditions within the molecular gas appear to change as a galaxy's ISM is affected by environmental processes. 13CO is detected across the sample, both directly and via stacking, while C18O is detected in a smaller number of systems. We use these data to study trends with global and radial galaxy properties. We show that the CO/13CO line ratio changes systematically with a variety of galaxy properties, including mean gas surface density, HI-deficiency and galaxy morphology. 13CO/C18O line ratios vary significantly, both radially and between galaxies, suggesting real variations in abundances are present. Such abundance changes may be due to star formation history differences, or speculatively even stellar initial mass function variations. We present a model where the optical depth of the molecular gas appears to change as a galaxy's ISM is affected by environmental processes. The molecular gas appears to become more transparent as the molecular medium is stripped, and then more opaque as the tightly bound remnant gas settles deep in the galaxy core. This explains the variations we see, and also helps explain similar observations in cluster early-type galaxies. Next generation simulations and dedicated observations of additional isotopologues could thus provide a powerful tool to help us understand the impact of environment on the ISM, and thus the quenching of galaxies. △ Less

Submitted 23 July, 2025; originally announced July 2025.

Comments: 12 pages, 11 figures, MNRAS accepted

Journal ref: Mon Not R Astron Soc (2025) 4031-4048

BASS. XLIV. Morphological preferences of local hard X-ray selected AGN

Authors: Miguel Parra Tello, Franz E. Bauer, Demetra De Cicco, Goran Doll, Michael Koss, Ezequiel Treister, Carolina Finlez, Marco Troncoso, Connor Auge, I. del Moral-Castro, Aeeree Chung, Kriti K. Gupta, Jeein Kim, Kyuseok Oh, Claudio Ricci, Federica Ricci, Alejandra Rojas, Turgay Caglar, Fiona Harrison, Meredith C. Powell, Daniel Stern, Benny Trakhtenbrot, C. Megan Urry

Abstract: We present morphological classifications for the hosts of 1189 hard X-ray selected (14-195 keV) active galactic nuclei (AGNs) from the Swift-BAT 105-month catalog as part of the BAT AGN Spectroscopic Survey (BASS). BASS provides a powerful all-sky census of nearby AGN, minimizing obscuration biases and providing a robust dataset for studying AGN-host galaxy connections. Classifications are based o… ▽ More We present morphological classifications for the hosts of 1189 hard X-ray selected (14-195 keV) active galactic nuclei (AGNs) from the Swift-BAT 105-month catalog as part of the BAT AGN Spectroscopic Survey (BASS). BASS provides a powerful all-sky census of nearby AGN, minimizing obscuration biases and providing a robust dataset for studying AGN-host galaxy connections. Classifications are based on volunteer-based visual inspection on the Zooniverse platform, adapted from Galaxy Zoo DECaLS (GZD). Dual-contrast grz color composite images, generated from public surveys (e.g., NOAO Legacy Survey, Pan-STARRS, SDSS) and dedicated observations enabled key morphological features to be identified. Our analysis reveals that, with respect to a control sample of inactive galaxies matched in redshift and i-band magnitude, BASS AGN hosts show a deficiency of smooth ellipticals (~70%) and disks with prominent arms (~80%), while displaying an excess of mergers or disturbed systems (~400%), and disk galaxies without a spiral structure (~300%). These trends suggest a preference for AGN activity in gas-rich, dynamically disturbed environments or transitional disk systems. We also find a higher bar fraction among AGN hosts than the control sample (~50% vs. ~30%). We further explore the relations between AGN properties (e.g., X-ray luminosity, black hole mass, and Eddington ratio) and host morphology, and find that high-luminosity and high-accretion AGN preferentially reside in smooth or point-like hosts. In parallel, lower-luminosity AGN are more common in disk galaxies. These results underscore the importance of morphological studies in understanding the fueling and feedback mechanisms that drive AGN activity and their role in galaxy evolution. Our dataset provides a valuable benchmark for future multiwavelength surveys (e.g. LSST, Roman, and Euclid) and automated morphological classification efforts. △ Less

Submitted 26 June, 2025; originally announced June 2025.

Comments: 20 pages, 24 figures. Accepted for publication on A&A

Journal ref: A&A 700, A111 (2025)

The MALATANG survey: Dense gas distribution on sub-kiloparsec scales across the disk of M82

Authors: Jian-Fa Wang, Yu Gao, Qing-Hua Tan, Xue-Jian Jiang, Li Ji, Zhi-Yu Zhang, Jun-Zhi Wang, Jun-Feng Wang, R. Thomas Greve, Yan Jiang, Ashley Bemis, Elias Brinks, Aeree Chung, J. Malcolm Currie, Richard de Grijs, Taotao Fang, C. Luis Ho, Bumhyun Lee, Satoki Matsushita, Michał Michałowski, Soojong Pak, Panomporn Poojon, G. Mark Rawlings, Amelie Saintonge, Yi-Chen Sun , et al. (1 additional authors not shown)

Abstract: We present observations of HCN J=4-3 and HCO^+ J=4-3 lines obtained with the James Clerk Maxwell Telescope as part of the MALATANG survey, combined with archival HCN J=1-0 and HCO^+ J=1-0 data from the Green Bank Telescope, to study the spatial distribution and excitation conditions of dense molecular gas in the disk of M82. We detect HCN J=4-3 and HCO^+ J=4-3 emission within the central region (<… ▽ More We present observations of HCN J=4-3 and HCO^+ J=4-3 lines obtained with the James Clerk Maxwell Telescope as part of the MALATANG survey, combined with archival HCN J=1-0 and HCO^+ J=1-0 data from the Green Bank Telescope, to study the spatial distribution and excitation conditions of dense molecular gas in the disk of M82. We detect HCN J=4-3 and HCO^+ J=4-3 emission within the central region (< 500 pc) of the galaxy, while the J=1-0 emission lines exhibit a more extended spatial distribution (> 700 pc). The dense gas shows a clear double-lobed structure in both spatial distribution and kinematics, with the HCN and HCO^+ J=4-3 lines in the southwest lobe blueshifted by ~ 40 km/s relative to the J=1-0 lines. The HCN J=4-3/1-0 and HCO^+ J=4-3/1-0 line-luminosity ratios range from 0.09 to 0.53 and from 0.14 to 0.87, respectively, with mean values of 0.18 +/- 0.04 and 0.36 +/- 0.06. The HCN ratio is lower than the typical average observed in nearby star-forming galaxies, whereas the HCO^+ ratio is comparatively higher, suggesting that the high-J HCN emission in M82 is significantly sub-thermally excited. Spatially, the peak values of the J=4-3/1-0 ratios are found in the northwest region of M82, coinciding with the galaxy-scale outflow. Elevated HCN/HCO^+ ratios are also detected in roughly the same area, potentially tracing local excitation enhancements driven by the outflow. The HCN/HCO^+ J=4-3 ratio across all detected regions ranges from 0.19 to 1.07 with a mean value of 0.41 +/- 0.11, which is significantly lower than the average J=1-0 ratio of 0.76 +/- 0.08. Both ratios are significantly lower than the average values observed in nearby star-forming galaxies, which could be related to the relatively low gas density and the presence of an extended photo-dissociation region in M82. △ Less

Submitted 26 June, 2025; v1 submitted 25 June, 2025; originally announced June 2025.

Journal ref: A&A 700, A72 (2025)

Black hole ringdown spectroscopy of curvature-coupled scalar and pseudoscalar fields

Authors: Adrian Ka-Wai Chung, Nicolás Yunes

Abstract: Remnant black holes formed in compact binary coalescences provide a clean setting for probing additional fields coupled to gravity. By analyzing the ringdown signals of the loudest LIGO-Virgo-KAGRA binary-black hole mergers, we search for massless curvature-coupled (pseudo)scalar fields arising in extensions to general relativity. We find no evidence for such fields and place 90\% credible upper l… ▽ More Remnant black holes formed in compact binary coalescences provide a clean setting for probing additional fields coupled to gravity. By analyzing the ringdown signals of the loudest LIGO-Virgo-KAGRA binary-black hole mergers, we search for massless curvature-coupled (pseudo)scalar fields arising in extensions to general relativity. We find no evidence for such fields and place 90\% credible upper limits on the coupling length scale, $\ell \lesssim (25$-$45)$ km, corresponding to scales significantly below the horizons of the remnant black holes. These results include the first gravitational-wave constraint on an axidilaton-type coupling. By isolating the ringdown phase and performing extensive robustness checks, our analysis provides a complementary observational probe to existing full-waveform constraints. As the gravitational-wave catalog expands, black hole ringdown spectroscopy will enable increasingly sensitive probes of gravity and additional fields using astrophysical black holes. △ Less

Submitted 28 July, 2026; v1 submitted 17 June, 2025; originally announced June 2025.

Comments: Match the published version

Journal ref: Phys. Rev. D 114, L021505 (2026)

Black hole spectroscopy: from theory to experiment

Authors: Emanuele Berti, Vitor Cardoso, Gregorio Carullo, Jahed Abedi, Niayesh Afshordi, Simone Albanesi, Vishal Baibhav, Swetha Bhagwat, José Luis Blázquez-Salcedo, Béatrice Bonga, Bruno Bucciotti, Giada Caneva Santoro, Pablo A. Cano, Collin Capano, Mark Ho-Yeuk Cheung, Cecilia Chirenti, Gregory B. Cook, Adrian Ka-Wai Chung, Marina De Amicis, Kyriakos Destounis, Oscar J. C. Dias, Walter Del Pozzo, Francisco Duque, Will M. Farr, Eliot Finch , et al. (43 additional authors not shown)

Abstract: The "ringdown" radiation emitted by oscillating black holes has great scientific potential. By carefully predicting the frequencies and amplitudes of black hole quasinormal modes and comparing them with gravitational-wave data from compact binary mergers we can advance our understanding of the two-body problem in general relativity, verify the predictions of the theory in the regime of strong and… ▽ More The "ringdown" radiation emitted by oscillating black holes has great scientific potential. By carefully predicting the frequencies and amplitudes of black hole quasinormal modes and comparing them with gravitational-wave data from compact binary mergers we can advance our understanding of the two-body problem in general relativity, verify the predictions of the theory in the regime of strong and dynamical gravitational fields, and search for physics beyond the Standard Model or new gravitational degrees of freedom. We summarize the state of the art in our understanding of black hole quasinormal modes in general relativity and modified gravity, their excitation, and the modeling of ringdown waveforms. We also review the status of LIGO-Virgo-KAGRA ringdown observations, data analysis techniques, and the bright prospects of the field in the era of LISA and next-generation ground-based gravitational-wave detectors. △ Less

Submitted 10 August, 2026; v1 submitted 29 May, 2025; originally announced May 2025.

Comments: 324 pages, 80 figures; v3: matches published version

Report number: RUP-25-10; YITP-25-64; RIKEN-iTHEMS-Report-25

Journal ref: Class. Quantum Grav. 43 (2026) 123001

Mapping the Star Formation and HI Gas Properties of Galaxies Along Large-scale Structures Around the Virgo Cluster

Authors: Hyein Yoon, O. Ivy Wong, Aeree Chung, Shan Huang

Abstract: We investigate the star formation and neutral atomic hydrogen (HI) gas properties of galaxies along three large-scale filaments and two galaxy groups in the wide field around the Virgo cluster. Our goal is to understand how galaxies are processed in low-density environments before falling into high-density regions. Combining the spatial distribution of galaxies with multiwavelength colors such as… ▽ More We investigate the star formation and neutral atomic hydrogen (HI) gas properties of galaxies along three large-scale filaments and two galaxy groups in the wide field around the Virgo cluster. Our goal is to understand how galaxies are processed in low-density environments before falling into high-density regions. Combining the spatial distribution of galaxies with multiwavelength colors such as W3-W1, NUV-r, and g-r, we find a predominance of blue galaxies across the structures, indicating normal-to-enhanced star formation, similar to that of isolated galaxies. However, one filament and one group show a significant number of red galaxies (32% and 20%, respectively), suggesting that star formation has been suppressed in low-density environments before reaching high-density regions. Intriguingly, these red galaxies span a wide range of stellar masses, and the presence of red dwarfs support that not only mass but also environment plays an important role in the quenching of star formation in cluster outskirts. One particular filament, potentially connected to Virgo, already has a group of red populations outside Virgo's R_200, making these galaxies good candidates for being "preprocessed" before entering the Virgo cluster. In addition, several galaxies in the filaments and groups possess relatively low HI gas contents, similar to cluster galaxies. However, the overall fraction of HI-deficient galaxies is not as significantly high as the fraction of red galaxies in these structures. This suggests that HI gas properties are less influenced by the environment than star formation properties in low-density regions, possibly due to gas replenishment through accretion. △ Less

Submitted 26 May, 2025; originally announced May 2025.

Comments: 24 pages, 14 figures, 4 tables, accepted for publication in ApJ

Towards entropic uncertainty relations for non-regular Hilbert spaces

Authors: Alejandro Corichi, Angel Garcia Chung, Federico Zadra

Abstract: The Entropic Uncertainty Relations (EUR) result from inequalities that are intrinsic to the Hilbert space and its dual with no direct connection to the Canonical Commutation Relations. Bialynicky-Mielcisnky obtained them in \cite{bialynicki1975uncertainty} attending Hilbert spaces with a Lebesgue measure. The analysis of these EUR in the context of singular Hilbert spaces has not been addressed. S… ▽ More The Entropic Uncertainty Relations (EUR) result from inequalities that are intrinsic to the Hilbert space and its dual with no direct connection to the Canonical Commutation Relations. Bialynicky-Mielcisnky obtained them in \cite{bialynicki1975uncertainty} attending Hilbert spaces with a Lebesgue measure. The analysis of these EUR in the context of singular Hilbert spaces has not been addressed. Singular Hilbert spaces are widely used in scenarios where some discretization of the space (or spacetime) is considered, e.g., loop quantum gravity, loop quantum cosmology and polymer quantum mechanics. In this work, we present an overview of the essential literature background and the road map we plan to follow to obtain the EUR in polymer quantum mechanics. △ Less

Submitted 24 March, 2025; originally announced March 2025.

Comments: 10 pages, conference proceeding

Quasinormal mode frequencies and gravitational perturbations of spinning black holes in modified gravity through METRICS: The dynamical Chern-Simons gravity case

Authors: Adrian Ka-Wai Chung, Kelvin Ka-Ho Lam, Nicolas Yunes

Abstract: We present the first precise calculations of the gravitational quasinormal-mode (QNM) frequencies for spinning black holes with dimensionless angular momenta $J/M^2 := a \lesssim 0.75$ in dynamical Chern-Simons gravity. Using the \textit{Metric pErTuRbations wIth speCtral methodS} (METRICS) framework, we compute the QNM frequencies of both axial and polar metric perturbations, focusing on the… ▽ More We present the first precise calculations of the gravitational quasinormal-mode (QNM) frequencies for spinning black holes with dimensionless angular momenta $J/M^2 := a \lesssim 0.75$ in dynamical Chern-Simons gravity. Using the \textit{Metric pErTuRbations wIth speCtral methodS} (METRICS) framework, we compute the QNM frequencies of both axial and polar metric perturbations, focusing on the $nl m = 022$, $033$, and $032$ modes. The METRICS frequencies for the 022 mode achieve numerical uncertainties $\lesssim 10^{-4}$ when $0 \leq a \leq 0.5$ and $\lesssim 10^{-3}$ for $0.5 \leq a \leq 0.75$, without decoupling or simplifying the linearized field equations. We also derive optimal fitting polynomials to enable efficient and accurate evaluations of the leading-order frequency shifts in these modes. The METRICS frequencies and fitting expressions are a robust and indispensable step toward enabling gravitational-wave ringdown tests of dynamical Chern-Simons gravity. △ Less

Submitted 29 June, 2025; v1 submitted 14 March, 2025; originally announced March 2025.

Comments: Match the version published by PRD

Journal ref: Phys. Rev. D 111, 124052 (2025)

The Stochastic Siren: Astrophysical Gravitational-Wave Background Measurements of the Hubble Constant

Authors: Bryce Cousins, Kristen Schumacher, Adrian Ka-Wai Chung, Colm Talbot, Thomas Callister, Daniel E. Holz, Nicolás Yunes

Abstract: We report the first measurement of the Hubble constant $H_0$ using the stochastic gravitational-wave background arising from binary black hole mergers. This astrophysical background is sensitive to the expansion history of the Universe and thus can be used for cosmological parameter inference independently of not only electromagnetic methods, but also gravitational-wave standard siren approaches.… ▽ More We report the first measurement of the Hubble constant $H_0$ using the stochastic gravitational-wave background arising from binary black hole mergers. This astrophysical background is sensitive to the expansion history of the Universe and thus can be used for cosmological parameter inference independently of not only electromagnetic methods, but also gravitational-wave standard siren approaches. We describe the background's cosmological dependence and show how it can be used as a ``stochastic siren'' to measure $H_0$. By analyzing existing resolved binary black hole mergers and the current non-detection of the background, we find that $H_0$ can be measured more accurately relative to using resolved mergers alone. We also note that the stochastic siren may serve a unique role in the Hubble tension in that the lower bound of the $H_0$ measurement would progressively increase with continued non-detection of the background. △ Less

Submitted 2 February, 2026; v1 submitted 3 March, 2025; originally announced March 2025.

Comments: Version accepted by PRL

Reference-Aligned Retrieval-Augmented Question Answering over Heterogeneous Proprietary Documents

Authors: Nayoung Choi, Grace Byun, Andrew Chung, Ellie S. Paek, Shinsun Lee, Jinho D. Choi

Abstract: Proprietary corporate documents contain rich domain-specific knowledge, but their overwhelming volume and disorganized structure make it difficult even for employees to access the right information when needed. For example, in the automotive industry, vehicle crash-collision tests, each costing hundreds of thousands of dollars, produce highly detailed documentation. However, retrieving relevant co… ▽ More Proprietary corporate documents contain rich domain-specific knowledge, but their overwhelming volume and disorganized structure make it difficult even for employees to access the right information when needed. For example, in the automotive industry, vehicle crash-collision tests, each costing hundreds of thousands of dollars, produce highly detailed documentation. However, retrieving relevant content during decision-making remains time-consuming due to the scale and complexity of the material. While Retrieval-Augmented Generation (RAG)-based Question Answering (QA) systems offer a promising solution, building an internal RAG-QA system poses several challenges: (1) handling heterogeneous multi-modal data sources, (2) preserving data confidentiality, and (3) enabling traceability between each piece of information in the generated answer and its original source document. To address these, we propose a RAG-QA framework for internal enterprise use, consisting of: (1) a data pipeline that converts raw multi-modal documents into a structured corpus and QA pairs, (2) a fully on-premise, privacy-preserving architecture, and (3) a lightweight reference matcher that links answer segments to supporting content. Applied to the automotive domain, our system improves factual correctness (+1.79, +1.94), informativeness (+1.33, +1.16), and helpfulness (+1.08, +1.67) over a non-RAG baseline, based on 1-5 scale ratings from both human and LLM judge. △ Less

Submitted 26 August, 2025; v1 submitted 26 February, 2025; originally announced February 2025.

Comments: Accepted to CIKM 2025 Applied Research Track

MSC Class: H.3

Enhanced imaging of M87*: Simulations with the EHT and extended-KVN

Authors: Ilje Cho, Jongho Park, Do-Young Byun, Taehyun Jung, Lindy Blackburn, Freek Roelofs, Andrew Chael, Dominic W. Pesce, Sheperd S. Doeleman, Sara Issaoun, Jae-Young Kim, Junhan Kim, Jose L. Gomez, Keiichi Asada, Bong Won Sohn, Sang-Sung Lee, Jongsoo Kim, Sascha Trippe, Aeree Chung

Abstract: The Event Horizon Telescope (EHT) has successfully revealed the shadow of the supermassive black hole, M87*, with an unprecedented angular resolution of approximately 20 uas at 230 GHz. However, because of limited short baseline lengths, the EHT has been constrained in its ability to recover larger scale jet structures. The extended Korean VLBI Network (eKVN) is committed to joining the EHT from 2… ▽ More The Event Horizon Telescope (EHT) has successfully revealed the shadow of the supermassive black hole, M87*, with an unprecedented angular resolution of approximately 20 uas at 230 GHz. However, because of limited short baseline lengths, the EHT has been constrained in its ability to recover larger scale jet structures. The extended Korean VLBI Network (eKVN) is committed to joining the EHT from 2024 that can improve short baseline coverage. This study evaluates the impact of the participation of eKVN in the EHT on the recovery of the M87* jet. Synthetic data, derived from a simulated M87* model, were observed using both the EHT and the combined EHT+eKVN arrays, followed by image reconstructions from both configurations. The results indicate that the inclusion of eKVN significantly improves the recovery of jet structures by reducing residual noise. Furthermore, jackknife tests, in which one or two EHT telescopes were omitted - simulating potential data loss due to poor weather - demonstrate that eKVN effectively compensates for these missing telescopes, particularly in short baseline coverage. Multi-frequency synthesis imaging at 86-230 GHz shows that the EHT+eKVN array enhances the recovered spectral index distribution compared to the EHT alone and improves image reconstruction at each frequency over single-frequency imaging. As the EHT continues to expand its array configuration and observing capabilities to probe black hole physics more in depth, the integration of eKVN into the EHT will significantly enhance the stability of observational results and improve image fidelity. This advancement will be particularly valuable for future regular monitoring observations, where consistent data quality is essential. △ Less

Submitted 20 January, 2025; originally announced January 2025.

Comments: 13 pages, 13 figures, 2 tables

Journal ref: Journal of The Korean Astronomical Society Vol.58 No.1 pp.17-29 (2025)

Is thermography a viable solution for detecting pressure injuries in dark skin patients?

Authors: Miriam Asare-Baiden, Kathleen Jordan, Andrew Chung, Sharon Eve Sonenblum, Joyce C. Ho

Abstract: Pressure injury (PI) detection is challenging, especially in dark skin tones, due to the unreliability of visual inspection. Thermography has been suggested as a viable alternative as temperature differences in the skin can indicate impending tissue damage. Although deep learning models have demonstrated considerable promise toward reliably detecting PI, the existing work fails to evaluate the per… ▽ More Pressure injury (PI) detection is challenging, especially in dark skin tones, due to the unreliability of visual inspection. Thermography has been suggested as a viable alternative as temperature differences in the skin can indicate impending tissue damage. Although deep learning models have demonstrated considerable promise toward reliably detecting PI, the existing work fails to evaluate the performance on darker skin tones and varying data collection protocols. In this paper, we introduce a new thermal and optical imaging dataset of 35 participants focused on darker skin tones where temperature differences are induced through cooling and cupping protocols. We vary the image collection process to include different cameras, lighting, patient pose, and camera distance. We compare the performance of a small convolutional neural network (CNN) trained on either the thermal or the optical images on all skin tones. Our preliminary results suggest that thermography-based CNN is robust to data collection protocols for all skin tones. △ Less

Submitted 15 November, 2024; originally announced November 2024.

Comments: 9 pages

Bayesian Search of Massive Scalar Fields from LIGO-Virgo-KAGRA Binaries

Authors: Yiqi Xie, Adrian Ka-Wai Chung, Thomas P. Sotiriou, Nicolás Yunes

Abstract: Massive scalar fields are promising candidates to address many unresolved problems in fundamental physics. We report the first model-agnostic Bayesian search of massive scalar fields in LIGO/Virgo/KAGRA gravitational-wave data. We find no evidence for such fields and place the most stringent upper limits on their coupling for scalar masses $\lesssim 2\times10^{-12}\,{\rm eV}$. We exemplify the str… ▽ More Massive scalar fields are promising candidates to address many unresolved problems in fundamental physics. We report the first model-agnostic Bayesian search of massive scalar fields in LIGO/Virgo/KAGRA gravitational-wave data. We find no evidence for such fields and place the most stringent upper limits on their coupling for scalar masses $\lesssim 2\times10^{-12}\,{\rm eV}$. We exemplify the strength of these bounds by applying them to massive scalar-Gauss-Bonnet gravity, finding the tightest constraints on the coupling constant to date, $\sqrt{α_{\rm GB}}\lesssim 1\,{\rm km}$ for scalar masses $\lesssim 10^{-13}\,{\rm eV}$ to 90% confidence. △ Less

Submitted 20 May, 2025; v1 submitted 18 October, 2024; originally announced October 2024.

Comments: 9+11 pages, 8 figures, text and references updated with correction to a mistake in the previous analysis, v2 matches the version published in PRL

Journal ref: Phys. Rev. Lett. 134, 191402 (2025)

Expanding Search Space with Diverse Prompting Agents: An Efficient Sampling Approach for LLM Mathematical Reasoning

Authors: Gisang Lee, Sangwoo Park, Junyoung Park, Andrew Chung, Sieun Park, Yoonah Park, Byungju Kim, Min-gyu Cho

Abstract: Large Language Models (LLMs) have exhibited remarkable capabilities in many complex tasks including mathematical reasoning. However, traditional approaches heavily rely on ensuring self-consistency within single prompting method, which limits the exploration of diverse problem-solving strategies. This study addresses these limitations by performing an experimental analysis of distinct prompting me… ▽ More Large Language Models (LLMs) have exhibited remarkable capabilities in many complex tasks including mathematical reasoning. However, traditional approaches heavily rely on ensuring self-consistency within single prompting method, which limits the exploration of diverse problem-solving strategies. This study addresses these limitations by performing an experimental analysis of distinct prompting methods within the domain of mathematical reasoning. Our findings demonstrate that each method explores a distinct search space, and this differentiation becomes more evident with increasing problem complexity. To leverage this phenomenon, we applied efficient sampling process that uniformly combines samples from these diverse methods, which not only expands the maximum search space but achieves higher performance with fewer runs compared to single methods. Especially, within the subset of difficult questions of MATH dataset named MATH-hard, The maximum search space was achieved while utilizing approximately 43% fewer runs than single methods on average. These findings highlight the importance of integrating diverse problem-solving strategies to enhance the reasoning abilities of LLMs. △ Less

Submitted 13 October, 2024; originally announced October 2024.

Comments: 6 pages, 4 figures

Towards Efficient Visual-Language Alignment of the Q-Former for Visual Reasoning Tasks

Authors: Sungkyung Kim, Adam Lee, Junyoung Park, Andrew Chung, Jusang Oh, Jay-Yoon Lee

Abstract: Recent advancements in large language models have demonstrated enhanced capabilities in visual reasoning tasks by employing additional encoders for aligning different modalities. While the Q-Former has been widely used as a general encoder for aligning several modalities including image, video, audio, and 3D with large language models, previous works on its efficient training and the analysis of i… ▽ More Recent advancements in large language models have demonstrated enhanced capabilities in visual reasoning tasks by employing additional encoders for aligning different modalities. While the Q-Former has been widely used as a general encoder for aligning several modalities including image, video, audio, and 3D with large language models, previous works on its efficient training and the analysis of its individual components have been limited. In this work, we investigate the effectiveness of parameter efficient fine-tuning (PEFT) the Q-Former using InstructBLIP with visual reasoning benchmarks ScienceQA and IconQA. We observe that applying PEFT to the Q-Former achieves comparable performance to full fine-tuning using under 2% of the trainable parameters. Additionally, we employ AdaLoRA for dynamic parameter budget reallocation to examine the relative importance of the Q-Former's sublayers with 4 different benchmarks. Our findings reveal that the self-attention layers are noticeably more important in perceptual visual-language reasoning tasks, and relative importance of FFN layers depends on the complexity of visual-language patterns involved in tasks. The code is available at https://github.com/AttentionX/InstructBLIP_PEFT. △ Less

Submitted 12 October, 2024; originally announced October 2024.

Comments: EMNLP 2024 Findings

Quasi-normal mode frequencies and gravitational perturbations of black holes with any subextremal spin in modified gravity through METRICS: the scalar-Gauss-Bonnet gravity case

Authors: Adrian Ka-Wai Chung, Nicolas Yunes

Abstract: The gravitational waves emitted in the ringdown phase of binary black-hole coalescence are a unique probe of strong gravity. Understanding how deviations from general relativity affect the ringdown phase of black holes, however, is extremely challenging, as it requires solving highly-coupled and sometimes higher-order partial differential equations. We here extend a novel approach, \textit{Metric… ▽ More The gravitational waves emitted in the ringdown phase of binary black-hole coalescence are a unique probe of strong gravity. Understanding how deviations from general relativity affect the ringdown phase of black holes, however, is extremely challenging, as it requires solving highly-coupled and sometimes higher-order partial differential equations. We here extend a novel approach, \textit{Metric pErTuRbations wIth speCtral methodS} (METRICS), to study the metric perturbations and the quasinormal mode frequencies of ringing black holes in modified gravity. We first derive the asymptotic behavior of metric perturbations at the event horizon and spatial infinity for rotating black holes beyond general relativity. We then extend the eigenvalue-perturbation theory approach of METRICS to allow us to compute the leading-order modified gravity corrections to the quasinormal-mode frequencies and metric perturbations. We apply METRICS to rotating black holes in scalar-Gauss-Bonnet gravity. Without decoupling or simplifying the linearized field equations in this theory, we compute the leading-order corrections to the quasinormal frequencies of the axial and polar perturbations of the $nlm = 022$, 021 and 033 modes of black holes of $a \leq 0.85$. The numerical accuracy of the METRICS frequencies is $\leq 10^{-5}$ for $a \leq 0.6$, $\lesssim 10^{-4}$ for $0.6 < a \leq 0.7 $, and $\lesssim 10^{-2}$ for $0.7 < a \leq 0.85 $ for all modes studied. We fit the frequencies as a polynomial in spin, whose coefficients (up to second order in spin) are consistent with those obtained in previous slow-rotating approximations. These results are the first accurate computations of the gravitational quasinormal-mode frequencies of rapidly rotating black holes (of $a \sim 0.85$) in scalar-Gauss-Bonnet gravity. △ Less

Submitted 7 September, 2024; v1 submitted 17 June, 2024; originally announced June 2024.

Comments: Matched the published version; abstract trimmed, please refer to the PDF for the full abstract; 24 pages, 8 figures, 6 tables

WISDOM Project -- XXI. Giant molecular clouds in the central region of the barred spiral galaxy NGC 613: a steep size -- linewidth relation

Authors: Woorak Choi, Martin Bureau, Lijie Liu, Michele Cappellari, Timothy A. Davis, Jindra Gensior, Fu-Heng Liang, Anan Lu, Sanghyuk Moon, Ilaria Ruffa, Thomas G. Williams, Aeree Chung

Abstract: NGC~613 is a nearby barred spiral galaxy with a nuclear ring. Exploiting high spatial resolution ($\approx20$ pc) Atacama Large Millimeter/sub-millimeter Array $^{12}$CO(1-0) observations, we study the giant molecular clouds (GMCs) in the nuclear ring and its vicinity, identifying $158$ spatially- and spectrally-resolved GMCs. The GMC sizes ($R_{\mathrm{c}}$) are comparable to those of the clouds… ▽ More NGC~613 is a nearby barred spiral galaxy with a nuclear ring. Exploiting high spatial resolution ($\approx20$ pc) Atacama Large Millimeter/sub-millimeter Array $^{12}$CO(1-0) observations, we study the giant molecular clouds (GMCs) in the nuclear ring and its vicinity, identifying $158$ spatially- and spectrally-resolved GMCs. The GMC sizes ($R_{\mathrm{c}}$) are comparable to those of the clouds in the Milky Way (MW) disc, but their gas masses, observed linewidths ($σ_{\mathrm{obs,los}}$) and gas mass surface densities are larger. The GMC size -- linewidth relation ($σ_{\mathrm{obs,los}}\propto R_{\mathrm{c}}^{0.77}$) is steeper than that of the clouds of the MW disc and centre, and the GMCs are on average only marginally gravitationally bound (with a mean virial parameter $\langleα_{\mathrm{obs,vir}}\rangle\approx1.7$). We discuss the possible origins of the steep size -- linewidth relation and enhanced observed linewidths of the clouds and suggest that a combination of mechanisms such as stellar feedback, gas accretion and cloud-cloud collisions, as well as the gas inflows driven by the large-scale bar, may play a role. △ Less

Submitted 30 May, 2024; v1 submitted 30 May, 2024; originally announced May 2024.

Comments: 15 pages, 8 figures, accepted for publication in MNRAS. arXiv admin note: text overlap with arXiv:2304.10471

The RSNA Abdominal Traumatic Injury CT (RATIC) Dataset

Authors: Jeffrey D. Rudie, Hui-Ming Lin, Robyn L. Ball, Sabeena Jalal, Luciano M. Prevedello, Savvas Nicolaou, Brett S. Marinelli, Adam E. Flanders, Kirti Magudia, George Shih, Melissa A. Davis, John Mongan, Peter D. Chang, Ferco H. Berger, Sebastiaan Hermans, Meng Law, Tyler Richards, Jan-Peter Grunz, Andreas Steven Kunz, Shobhit Mathur, Sandro Galea-Soler, Andrew D. Chung, Saif Afat, Chin-Chi Kuo, Layal Aweidah , et al. (15 additional authors not shown)

Abstract: The RSNA Abdominal Traumatic Injury CT (RATIC) dataset is the largest publicly available collection of adult abdominal CT studies annotated for traumatic injuries. This dataset includes 4,274 studies from 23 institutions across 14 countries. The dataset is freely available for non-commercial use via Kaggle at https://www.kaggle.com/competitions/rsna-2023-abdominal-trauma-detection. Created for the… ▽ More The RSNA Abdominal Traumatic Injury CT (RATIC) dataset is the largest publicly available collection of adult abdominal CT studies annotated for traumatic injuries. This dataset includes 4,274 studies from 23 institutions across 14 countries. The dataset is freely available for non-commercial use via Kaggle at https://www.kaggle.com/competitions/rsna-2023-abdominal-trauma-detection. Created for the RSNA 2023 Abdominal Trauma Detection competition, the dataset encourages the development of advanced machine learning models for detecting abdominal injuries on CT scans. The dataset encompasses detection and classification of traumatic injuries across multiple organs, including the liver, spleen, kidneys, bowel, and mesentery. Annotations were created by expert radiologists from the American Society of Emergency Radiology (ASER) and Society of Abdominal Radiology (SAR). The dataset is annotated at multiple levels, including the presence of injuries in three solid organs with injury grading, image-level annotations for active extravasations and bowel injury, and voxelwise segmentations of each of the potentially injured organs. With the release of this dataset, we hope to facilitate research and development in machine learning and abdominal trauma that can lead to improved patient care and outcomes. △ Less

Submitted 29 May, 2024; originally announced May 2024.

Comments: 40 pages, 2 figures, 3 tables

Ringing out General Relativity: Quasi-normal mode frequencies for black holes of any spin in modified gravity

Authors: Adrian Ka-Wai Chung, Nicolas Yunes

Abstract: After black holes collide, the remnant settles to a stationary state by emitting gravitational waves. Once non-linearities subside, these ringdown waves are dominated by exponentially-damped sinusoids, or quasinormal modes. We develop a general method using perturbative spectral expansions to calculate the quasinormal-mode frequencies and damping times in a wide class of modified gravity theories… ▽ More After black holes collide, the remnant settles to a stationary state by emitting gravitational waves. Once non-linearities subside, these ringdown waves are dominated by exponentially-damped sinusoids, or quasinormal modes. We develop a general method using perturbative spectral expansions to calculate the quasinormal-mode frequencies and damping times in a wide class of modified gravity theories for black holes with any subextremal spin. We apply this method to scalar-Gauss-Bonnet gravity to show its accuracy, thus enabling robust ringdown tests with gravitational wave data. △ Less

Submitted 1 November, 2024; v1 submitted 20 May, 2024; originally announced May 2024.

Comments: 5 pages, 2 figures; matched the version published by Phys. Rev. Lett

Journal ref: Phys. Rev. Lett. 133, 181401 (2024)

Towards Building Autonomous Data Services on Azure

Authors: Yiwen Zhu, Yuanyuan Tian, Joyce Cahoon, Subru Krishnan, Ankita Agarwal, Rana Alotaibi, Jesús Camacho-Rodríguez, Bibin Chundatt, Andrew Chung, Niharika Dutta, Andrew Fogarty, Anja Gruenheid, Brandon Haynes, Matteo Interlandi, Minu Iyer, Nick Jurgens, Sumeet Khushalani, Brian Kroth, Manoj Kumar, Jyoti Leeka, Sergiy Matusevych, Minni Mittal, Andreas Mueller, Kartheek Muthyala, Harsha Nagulapalli , et al. (13 additional authors not shown)

Abstract: Modern cloud has turned data services into easily accessible commodities. With just a few clicks, users are now able to access a catalog of data processing systems for a wide range of tasks. However, the cloud brings in both complexity and opportunity. While cloud users can quickly start an application by using various data services, it can be difficult to configure and optimize these services to… ▽ More Modern cloud has turned data services into easily accessible commodities. With just a few clicks, users are now able to access a catalog of data processing systems for a wide range of tasks. However, the cloud brings in both complexity and opportunity. While cloud users can quickly start an application by using various data services, it can be difficult to configure and optimize these services to gain the most value from them. For cloud providers, managing every aspect of an ever-increasing set of data services, while meeting customer SLAs and minimizing operational cost is becoming more challenging. Cloud technology enables the collection of significant amounts of workload traces and system telemetry. With the progress in data science (DS) and machine learning (ML), it is feasible and desirable to utilize a data-driven, ML-based approach to automate various aspects of data services, resulting in the creation of autonomous data services. This paper presents our perspectives and insights on creating autonomous data services on Azure. It also covers the future endeavors we plan to undertake and unresolved issues that still need attention. △ Less

Submitted 2 May, 2024; originally announced May 2024.

Comments: SIGMOD Companion of the 2023 International Conference on Management of Data. 2023

Detection of extragalactic anomalous microwave emission in NGC 2903 using KVN single-dish observations

Authors: Panomporn Poojon, Aeree Chung, Thiem Hoang, Junhyun Baek, Hiroyuki Nakanishi, Tomoya Hirota, Chao-Wei Tsai

Abstract: We present the results of the single-dish observations using the Korean VLBI Network to search for anomalous microwave emission (AME) in nearby galaxies. The targets were selected from MApping the dense moLecular gAs in the sTrongest stAr-formiNg Galaxies (MALATANG), a legacy survey project of the James Clerk Maxwell Telescope. The MALATANG galaxies are good representatives of local galaxies with… ▽ More We present the results of the single-dish observations using the Korean VLBI Network to search for anomalous microwave emission (AME) in nearby galaxies. The targets were selected from MApping the dense moLecular gAs in the sTrongest stAr-formiNg Galaxies (MALATANG), a legacy survey project of the James Clerk Maxwell Telescope. The MALATANG galaxies are good representatives of local galaxies with enhanced nuclear activity associated with star formation and/or AGN, providing IR-bright galaxy samples; thus, they are good candidates for AME hosts. Combining with the ancillary data, we investigated the radio-IR spectral energy distribution (SED), while searching for the AME signals in five galaxies. The AME in NGC 2903 was well detected at a significant confidence level, whereas that in NGC 2146 and M82 was marginal. NGC 1068 and Arp 299 indicated no significant hints, and we provided the upper limits for the AME. The best-fit SED exhibited local peaks of the AME components at higher frequencies and with stronger peak fluxes than those in the previous studies. This suggested the origin of AME being denser environments such as molecular clouds or photodissociation regions rather than warm neutral/ionized medium as commonly suggested by previous studies. Further, our AME-detected targets were observed to exhibit higher specific star-formation rates than the other extragalactic AME hosts. Furthermore, AME favored starburst galaxies among our sample rather than AGN hosts. Consequently, this might imply that AGNs are excessively harsh environments for tiny dust to survive. △ Less

Submitted 5 February, 2024; originally announced February 2024.

Comments: 20 pages, 10 figures, accepted for publication in ApJ

Statistical Guarantees for Link Prediction using Graph Neural Networks

Authors: Alan Chung, Amin Saberi, Morgane Austern

Abstract: This paper derives statistical guarantees for the performance of Graph Neural Networks (GNNs) in link prediction tasks on graphs generated by a graphon. We propose a linear GNN architecture (LG-GNN) that produces consistent estimators for the underlying edge probabilities. We establish a bound on the mean squared error and give guarantees on the ability of LG-GNN to detect high-probability edges.… ▽ More This paper derives statistical guarantees for the performance of Graph Neural Networks (GNNs) in link prediction tasks on graphs generated by a graphon. We propose a linear GNN architecture (LG-GNN) that produces consistent estimators for the underlying edge probabilities. We establish a bound on the mean squared error and give guarantees on the ability of LG-GNN to detect high-probability edges. Our guarantees hold for both sparse and dense graphs. Finally, we demonstrate some of the shortcomings of the classical GCN architecture, as well as verify our results on real and synthetic datasets. △ Less

Submitted 7 February, 2024; v1 submitted 4 February, 2024; originally announced February 2024.

Discovery of a large-scale H I plume in the NGC 7194 Group

Authors: Mina Pak, Junhyun Baek, Joon Hyeop Lee, Aeree Chung, Matt Owers, Hyunjin Jeong, Eon-Chang Sung, Yun-Kyeong Sheen

Abstract: We present the discovery of a new H I structure in the NGC 7194 group from the observations using the Karl G. Jansky Very Large Array. NGC 7194 group is a nearby (z ~ 0.027) small galaxy group with five quiescent members. The observations reveal a 200 kpc-long H I plume that spans the entire group with a total mass of M$_{HI}$ = 3.4 x 10$^{10}$ M$_{\odot}$. The line-of-sight velocity of the H I ga… ▽ More We present the discovery of a new H I structure in the NGC 7194 group from the observations using the Karl G. Jansky Very Large Array. NGC 7194 group is a nearby (z ~ 0.027) small galaxy group with five quiescent members. The observations reveal a 200 kpc-long H I plume that spans the entire group with a total mass of M$_{HI}$ = 3.4 x 10$^{10}$ M$_{\odot}$. The line-of-sight velocity of the H I gas gradually increases from south (7200 km s$^{-1}$) to north (8200 km $^{-1}$), and the local velocity dispersion is up to 70 km s$^{-1}$. The structure is not spatially coincident with any member galaxies but it shows close associations with a number of blue star-forming knots. Intragroup H I gas is not rare, but this particular structure is still one of the unusual cases in the sense that it does not show any clear connection with sizable galaxies in the group. We discuss the potential origins of this large-scale H I gas in the NGC 7194 group and its relation with the intergalactic star-forming knots. We propose that this HI feature could have originated from tidal interactions among group members or the infall of a late-type galaxy into the group. Alternatively, it might be leftover gas from flyby intruders. △ Less

Submitted 15 December, 2023; originally announced December 2023.

Comments: 9 pages, 3 figures

DVQI: A Multi-task, Hardware-integrated Artificial Intelligence System for Automated Visual Inspection in Electronics Manufacturing

Authors: Audrey Chung, Francis Li, Jeremy Ward, Andrew Hryniowski, Alexander Wong

Abstract: As electronics manufacturers continue to face pressure to increase production efficiency amid difficulties with supply chains and labour shortages, many printed circuit board assembly (PCBA) manufacturers have begun to invest in automation and technological innovations to remain competitive. One such method is to leverage artificial intelligence (AI) to greatly augment existing manufacturing proce… ▽ More As electronics manufacturers continue to face pressure to increase production efficiency amid difficulties with supply chains and labour shortages, many printed circuit board assembly (PCBA) manufacturers have begun to invest in automation and technological innovations to remain competitive. One such method is to leverage artificial intelligence (AI) to greatly augment existing manufacturing processes. In this paper, we present the DarwinAI Visual Quality Inspection (DVQI) system, a hardware-integration artificial intelligence system for the automated inspection of printed circuit board assembly defects in an electronics manufacturing environment. The DVQI system enables multi-task inspection via minimal programming and setup for manufacturing engineers while improving cycle time relative to manual inspection. We also present a case study of the deployed DVQI system's performance and impact for a top electronics manufacturer. △ Less

Submitted 14 December, 2023; originally announced December 2023.

Comments: 8 pages

Spectral method for metric perturbations of black holes: Kerr background case in general relativity

Authors: Adrian Ka-Wai Chung, Pratik Wagle, Nicolas Yunes

Abstract: We present a novel approach, $\textit{Metric pErTuRbations wIth speCtral methodS}$ (METRICS), to calculate the gravitational metric perturbations and the quasinormal-mode frequencies of rotating black holes of any spin without decoupling the linearized field equations. We demonstrate the method by applying it to perturbations of Kerr black holes of any spin, simultaneously solving all ten lineariz… ▽ More We present a novel approach, $\textit{Metric pErTuRbations wIth speCtral methodS}$ (METRICS), to calculate the gravitational metric perturbations and the quasinormal-mode frequencies of rotating black holes of any spin without decoupling the linearized field equations. We demonstrate the method by applying it to perturbations of Kerr black holes of any spin, simultaneously solving all ten linearized Einstein equations in the Regge-Wheeler gauge through purely algebraic methods and computing the fundamental (co-rotating) quadrupole mode frequency at various spins. We moreover show that the METRICS approach is accurate and precise, yielding (i) quasinormal mode frequencies that agree with Leaver's, continuous-fraction solution with a relative fractional error smaller than $10^{-5}$ for all dimensionless spins below up to 0.95, and (ii) metric perturbations that lead to Teukolsky functions that also agree with Leaver's solution with mismatches below $1\%$ for all spins below 0.9. By not requiring the decoupling or the angular separation of the linearized field equations, the METRICS approach has the potential to be straightforwardly adapted for the computation of the quasinormal-mode frequencies of rotating black holes of any spin beyond general relativity or in the presence of matter. △ Less

Submitted 3 March, 2024; v1 submitted 13 December, 2023; originally announced December 2023.

Comments: 24 pages of main text, 12 figures, match the published version

Journal ref: Phys. Rev. D 109, 044072 (2024)

Unraveling the Complex Structure of AGN-driven Outflows. VI. Strong Ionized Outflows in Type 1 AGNs and the Outflow Size-Luminosity Relation

Authors: Changseok Kim, Jong-Hak Woo, Rongxin Luo, Aeree Chung, Junhyun Baek, Huynh Anh N. Le, Donghoon Son

Abstract: We present spatially resolved gas kinematics, ionization, and energetics of 11 type 1 and 5 type 2 active galactic nuclei (AGNs) with strong ionized gas outflows at z $<0.3$ using Gemini Multi-Object Spectrograph Integral Field Unit (GMOS-IFU) data. We find a strongly blueshifted region in [OIII] velocity maps, representing an approaching cone in biconical outflows, and blueshifted and redshifted… ▽ More We present spatially resolved gas kinematics, ionization, and energetics of 11 type 1 and 5 type 2 active galactic nuclei (AGNs) with strong ionized gas outflows at z $<0.3$ using Gemini Multi-Object Spectrograph Integral Field Unit (GMOS-IFU) data. We find a strongly blueshifted region in [OIII] velocity maps, representing an approaching cone in biconical outflows, and blueshifted and redshifted regions in H$α$ velocity maps, which show gravitationally rotating kinematics. AGN photoionization is dominant in the central region of most targets, and some of them also show ring-like structures of LINER or composite that surround the AGN-dominated center. Following our previous studies, we kinematically determine outflow sizes by the ratio between [OIII] and stellar velocity dispersion. Outflow sizes of type 1 AGNs follow the same kinematic outflow size-[OIII] luminosity relation obtained from the type 2 IFU sample in Kang & Woo and Luo (updated slope $0.29\pm0.04$), while they are limited to the central kpc scales, indicating the lack of global impact of outflows on the interstellar medium. Small mass outflow rates and large star formation rates of the combined sample support that there is no evidence of rapid star formation quenching by outflows, which is consistent with the delayed AGN feedback. △ Less

Submitted 12 October, 2023; v1 submitted 10 October, 2023; originally announced October 2023.

Comments: 27 pages, 18 figures, Accepted for publication in ApJ

AMUSE-antlia I: Nuclear X-ray properties of early-type galaxies in a dynamically young galaxy cluster

Authors: Zhensong Hu, Yuanyuan Su, Zhiyuan Li, Kelley M. Hess, Ralph P. Kraft, William R. Forman, Paul E. J. Nulsen, Sarrvesh S. Sridhar, Andra Stroe, Junhyun Baek, Aeree Chung, Dirk Grupe, Hao Chen, Jimmy A. Irwin, Christine Jones, Scott W. Randall, Elke Roediger

Abstract: To understand the formation and growth of supermassive black holes (SMBHs) and their co-evolution with host galaxies, it is essential to know the impact of environment on the activity of active galactic nuclei (AGN). We present new Chandra X-ray observations of nuclear emission from member galaxies in the Antlia cluster, the nearest non-cool core and the nearest merging galaxy cluster, residing at… ▽ More To understand the formation and growth of supermassive black holes (SMBHs) and their co-evolution with host galaxies, it is essential to know the impact of environment on the activity of active galactic nuclei (AGN). We present new Chandra X-ray observations of nuclear emission from member galaxies in the Antlia cluster, the nearest non-cool core and the nearest merging galaxy cluster, residing at D = 35.2 Mpc. Its inner region, centered on two dominant galaxies NGC 3268 and NGC 3258, has been mapped with three deep Chandra ACIS-I pointings. Nuclear X-ray sources are detected in 7/84 (8.3%) early-type galaxies (ETG) and 2/8 (25%) late-type galaxies with a median detection limit of 8x10^38 erg/s. All nuclear X-ray sources but one have a corresponding radio continuum source detected by MeerKAT at the L-band. Nuclear X-ray sources detected in early-type galaxies are considered as the genuine X-ray counterpart of low-luminosity AGN. When restricted to a detection limit of logLx(erg/s) > 38.9 and a stellar mass of 10 < log Ms(Msun) <11.6, 6/11 (54.5%) ETG are found to contain an X-ray AGN in Antlia, exceeding the AGN occupation fraction of 7/39 (18.0%) and 2/12 (16.7%) in the more relaxed, cool core clusters, Virgo and Fornax, respectively, and rivaling that of the AMUSE-Field ETG of 27/49 (55.1%). Furthermore, more than half of the X-ray AGN in Antlia are hosted by its younger subcluster, centered on NGC 3258. We believe that this is because SMBH activity is enhanced in a dynamically young cluster compared to relatively relaxed clusters. △ Less

Submitted 24 August, 2023; originally announced August 2023.

Comments: 14 pages, 8 figures, 2 tables, accepted for publication in The Astrophysical Journal