Showing 1–50 of 810 results for author: Chapman, S

CCAT: a two-octave 1.024 GHz KID readout featuring an overlap-channel polyphase synthesis filter bank on RFSoC

Authors: Ruixuan, Xie, Adrian K. Sinclair, James Burgoyne, Maxwell Chapman, Scott Chapman, Steve K. Choi, Anthony I. Huber, Ben Keller, Michael D. Niemack

Abstract: Next-generation submillimeter instruments require gigahertz-scale readout bandwidths to support the growing detector counts of large microwave kinetic inductance detector (KID) arrays. Designed to meet the readout bandwidth and tone-capacity requirements of the CCAT Prime-Cam 850 GHz and 410 GHz instrument modules, we developed our second-generation (Gen2) KID readout system on a Xilinx ZCU111 rad… ▽ More Next-generation submillimeter instruments require gigahertz-scale readout bandwidths to support the growing detector counts of large microwave kinetic inductance detector (KID) arrays. Designed to meet the readout bandwidth and tone-capacity requirements of the CCAT Prime-Cam 850 GHz and 410 GHz instrument modules, we developed our second-generation (Gen2) KID readout system on a Xilinx ZCU111 radio frequency system-on-chip (RFSoC), based on a parallelized overlap-channel polyphase synthesis filter bank and a companion wideband receiving channelizer. This two-octave architecture reads out four independent RF networks, each with 1.024 GHz instantaneous bandwidth and up to 2048 detectors. The polyphase synthesis doubles the baseline channel count and bandwidth, and enables on-the-fly control of individual tone frequency, amplitude and phase, facilitating optimized KID biasing and providing a gateway to tone tracking. These capabilities may also be useful more broadly across Prime-Cam and in similar frequency-division multiplexed (FDM) readout systems. We present the design in DSP simulation, and measurements in RF loopback as well as with two KID test chips, one spanning the full two-octave band. Loopback measurements demonstrate comparable noise performance between the first-generation (Gen1) baseline and Gen2; preliminary on/off-resonance measurements indicate detector-noise-limited operation for the majority of channels; and the digital channel crosstalk is measured and discussed. We report FPGA resource and power utilization and assess scalability toward future large-format KID instruments. △ Less

Submitted 13 August, 2026; originally announced August 2026.

Comments: Submitted to the proceedings of Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XIII, SPIE Astronomical Telescopes + Instrumentation 2026. Paper No. 14156-101

CCAT: Design and Characterization of the 350 GHz Instrument Module

Authors: Ben Keller, Jordan Wheeler, Cody J. Duell, Darshan A. Patel, Jason Austermann, Baird D. Bankovic, James Burgoyne, Scott Chapman, Steve K. Choi, Rodrigo Freundt, Min Gao, Eliza Gazda, Anthony I. Huber, Johannes Hubmayr, Lawrence T. Lin, Quintin Meyers, Paul Malachuk, Alicia Middleton, Michael D. Niemack, Tilak M. Patel, Anna Vaskuri, Eve Vavagiakis, Michael R. Vissers, Samantha Walker, Yuhan Wang , et al. (2 additional authors not shown)

Abstract: The CCAT Collaboration's Prime-Cam instrument will soon be deployed to the Fred Young Submillimeter Telescope (FYST) in Chile's Atacama Desert. Featuring prominently in Prime-Cam's calibration and early science observations will be the 350 GHz instrument module, a broadband camera that will field more than 10,000 microwave kinetic inductance detectors (KIDs) across three detector arrays. Forecasts… ▽ More The CCAT Collaboration's Prime-Cam instrument will soon be deployed to the Fred Young Submillimeter Telescope (FYST) in Chile's Atacama Desert. Featuring prominently in Prime-Cam's calibration and early science observations will be the 350 GHz instrument module, a broadband camera that will field more than 10,000 microwave kinetic inductance detectors (KIDs) across three detector arrays. Forecasts show this module will be capable of making the most sensitive to-date measurements of polarized dust emission over a large fraction of the sky at this frequency, enabling new galactic polarization science and improved understanding of cosmological foregrounds. In this work we discuss the design of the 350 GHz instrument module, covering aspects of the optics, readout, and detector arrays. We then report on the results of in-lab testing of the fully-integrated module, achieving stable cryogenic performance with a 100 mK focal plane, high detector yield, and a passband comparable to designed specifications. Upon completion of these tests, this module was shipped to the telescope site in Chile for integration in Prime-Cam. △ Less

Submitted 5 August, 2026; originally announced August 2026.

Comments: 13 pages, 12 figures, 2 tables

CCAT: Characterization of the first science-grade MKID array for the Prime-Cam 850 GHz module

Authors: Anthony I. Huber, Jordan Wheeler, James Burgoyne, Scott Chapman, Jason Austermann, James Beall, Steve K. Choi, Doug Henke, Johannes Hubmayr, Ben Keller, Matthew Koc, Jeff van Lanen, Tilak Patel, Adrian Sinclair, Anna Vaskuri, Eve M. Vavagiakis, Michael Vissers, Ruixuan, Xie

Abstract: The Fred Young Submillimeter Telescope (FYST) is a 6-meter crossed-Dragone telescope developed by the CCAT collaboration. Sited at 5600 m on Cerro Chajnantor in the Atacama Plateau of Chile, FYST aims to provide superior atmospheric transmission and a wide field of view for submillimeter observations. Prime-Cam is a first-generation instrument for FYST designed to house up to seven separate instru… ▽ More The Fred Young Submillimeter Telescope (FYST) is a 6-meter crossed-Dragone telescope developed by the CCAT collaboration. Sited at 5600 m on Cerro Chajnantor in the Atacama Plateau of Chile, FYST aims to provide superior atmospheric transmission and a wide field of view for submillimeter observations. Prime-Cam is a first-generation instrument for FYST designed to house up to seven separate instrument modules. Among these, the 850 GHz module represents the highest-frequency band and is optimized for ultra-sensitive broadband polarimetry and imaging. This module is designed to deploy ~38,000 polarization-sensitive lumped-element titanium-nitride (TiN) microwave kinetic inductance detectors (MKIDs) across three arrays. Thus the 850 GHz module will have the most submillimeter MKIDs in a single instrument module to date. These detectors have adopted a novel two-octave design to maximize the multiplexing achieved using a RFSoC readout system. We review the design parameters and fabrication process for the first 850 GHz science-grade array. The preliminary measurements of the array show a fabrication yield of 99%, highlighting the successful application of the design and fabrication process. We further present the cryogenic characterization of the first full MKID array developed for the Prime-Cam 850 GHz module. Multiple tests were performed on the devices including resonator frequency mapping, quality factor measurements, optical load sweeps and noise performance. From these measurements, we discuss the measured optical efficiency, sensitivity, and uniformity across the array and the expected on-sky performance of the module. The 850 GHz module will be deployed for observing in 2027. △ Less

Submitted 5 August, 2026; originally announced August 2026.

Comments: 12 pages, 8 figures

CCAT: The 410 GHz camera module for FYST - design and testing of the MKID focal plane

Authors: Scott C. Chapman, Jordan Wheeler, Anthony Huber, Jason Austermann, James A. Beall, James Burgoyne, Max Chapman, Jesslyn Devina, Douglas Henke, Johannes Hubmayr, Dylan Lockyer, Michael Niemack, Tilak M. Patel, Colin Ross, Douglas Scott, Adrian Sinclair, Eve Vavagiakis, Michael R. Vissers, Ruixuan, Xie

Abstract: Prime-Cam, the primary first-light instrument for the Fred Young Submillimeter Telescope (FYST) developed by the Cerro Chajnantor Atacama Telescope (CCAT) Collaboration, will accommodate seven modules. Here we describe the off-central 410 GHz imager/polarimeter. The 410 GHz instrument is a camera module for CCAT funded by the Canadian Foundation for Innovation, being developed as a collaboration b… ▽ More Prime-Cam, the primary first-light instrument for the Fred Young Submillimeter Telescope (FYST) developed by the Cerro Chajnantor Atacama Telescope (CCAT) Collaboration, will accommodate seven modules. Here we describe the off-central 410 GHz imager/polarimeter. The 410 GHz instrument is a camera module for CCAT funded by the Canadian Foundation for Innovation, being developed as a collaboration between Dalhousie University, University of British Columbia (UBC), National Research Council (NRC) - Herzberg, and Duke University. With atmospheric loading in the 410 GHz window being significantly higher than at 350 GHz (but substantially lower than 850 GHz), we assess four MKID test devices with varying inductor volume for performance at 410 GHz. We propose a design for an array of ~6,700 horn-coupled TiN MKIDs optimized for use at 410 GHz, with a planned ~20,000 MKIDs over three arrays, exploring mapping speed versus detector number. We test the four MKID devices optically and assess optimal Qi/Qc and responsivity for the 410 GHz atmospheric window atop Cerro Chajnantor. The detectors will be designed in frequency to be efficiently readout with a second generation, two octave readout (based on the Xilinx RFSoC board), with over 4000 detectors per board. △ Less

Submitted 4 August, 2026; originally announced August 2026.

Comments: 13 pages, SPIE 2026 Copenhagen

Data reduction pipeline for the SuMAC millimeter-wave spectrometer at the LMT

Authors: A. M. Lapuente, P. S. Barry, M. Becerril-Tapia, C. Benson, C. M. Bradford, T. Brien, S. C. Chapman, S. Doyle, V. Gómez-Rivera, S. Hailey-Dunsheath, J. Hernández-Aguilar, J. L. Hernández-Rebollar, D. Hughes, E. Kane, K. S. Karkare, R. McGeehan, R. Naranjo-Romero, A. Papageorgiou, J. G. Redford, I. Rodríguez-Montoya, S. Rowe, D. O. Sánchez-Argüelles, S. Savorgnano, A. Tan, J. Vega-Méndez

Abstract: We present the data reduction and analysis pipeline for the SuperSpec-MUSCAT Collaboration (SuMAC) along with several key science data products. In Summer 2025, SuperSpec on-chip spectrometers operating from $190-300$ GHz at $R\sim200$ were deployed in the MUSCAT cryostat at the Large Millimeter Telescope, obtaining several days of on-sky data. Analysis of these data has been used to characterize… ▽ More We present the data reduction and analysis pipeline for the SuperSpec-MUSCAT Collaboration (SuMAC) along with several key science data products. In Summer 2025, SuperSpec on-chip spectrometers operating from $190-300$ GHz at $R\sim200$ were deployed in the MUSCAT cryostat at the Large Millimeter Telescope, obtaining several days of on-sky data. Analysis of these data has been used to characterize noise performance and study spectra of various astrophysical sources, establishing the viability of deploying SuperSpec detectors in future instruments. These proceedings discuss the modular data reduction pipeline which uses timestreams of the kinetic inductance detectors (KIDs) and auxiliary instrument data to generate a variety of data products. We present an on-sky calibration method for converting the KID fractional frequency shift to on-sky brightness temperature. The mapmaking module generates 3D data cubes of extended sources, while the spectrum module produces a millimeter-wave spectrum of an object. The observations all incorporate measurements of the atmosphere to model and correct for absorption. We also discuss data processing choices including detector weighting, despiking, and notch filtering. Finally, we present preliminary data products including detection of carbon monoxide in NGC 253 and spectral maps of the central region of the Orion KL nebula. △ Less

Submitted 4 August, 2026; originally announced August 2026.

Comments: 12 pages, 8 figures, submitted to the 2026 Society of Photo-Optical Instrumentation Engineers Astronomical Telescopes + Instrumentation (SPIE Astronomical Telescopes + Instrumentation 2026) proceedings

SuMAC: On-sky demonstration of multi-pixel on-chip millimeter-wave spectroscopy at the Large Millimeter Telescope

Authors: Marcial Becerril-Tapia, Peter S. Barry, Christopher S. Benson, Charles M. Bradford, Thomas L. R. Brien, Scott C. Chapman, Simon Doyle, Víctor Gómez-Rivera, Steven Hailey-Dunsheath, Jesús Hernández-Aguilar, José Luis Hernández-Rebollar, David H. Hughes, Elijah Kane, Kirit S. Karkare, Alex M. Lapuente, Ryan McGeehan, Raúl Naranjo-Romero, Andreas Papageorgiou, Joseph Redford, Iván Rodríguez-Montoya, Sam Rowe, David O. Sánchez-Argüelles, Sofia Savorgnano, Annie Tan, Jair Vega-Méndez

Abstract: The SuperSpec-MUSCAT Collaboration (SuMAC) is an effort to operate SuperSpec spectrometers in the MUSCAT instrument at the Large Millimeter Telescope (LMT). SuperSpec is an on-chip filterbank spectrometer using kinetic inductance detectors (KIDs), with moderate $R\sim 200$ spectral resolution for observing in the 1 mm atmospheric window (190-300 GHz). While nominally a continuum camera operating a… ▽ More The SuperSpec-MUSCAT Collaboration (SuMAC) is an effort to operate SuperSpec spectrometers in the MUSCAT instrument at the Large Millimeter Telescope (LMT). SuperSpec is an on-chip filterbank spectrometer using kinetic inductance detectors (KIDs), with moderate $R\sim 200$ spectral resolution for observing in the 1 mm atmospheric window (190-300 GHz). While nominally a continuum camera operating a 1.1 mm, MUSCAT was also designed to operate as a testbed for pioneering detection technologies. In July 2025, three SuperSpec devices were installed and commissioned in the MUSCAT cryostat with minimal modifications to the system. This work presents an overview of SuperSpec's deployment and performance in MUSCAT along with the main results from the Summer 2025 observation campaign. Highlights include the detection of CO emission line in the galaxy NGC253, mapping the Orion KL region, and preliminary line intensity mapping scans. △ Less

Submitted 4 August, 2026; originally announced August 2026.

Comments: 16 pages, 12 figures, submitted to the 2026 Society of Photo-Optical Instrumentation Engineers Astronomical Telescopes + Instrumentation (SPIE Astronomical Telescopes + Instrumentation 2026) proceedings

CCAT: Optical Design of the 410 GHz Prime-Cam Module

Authors: Tilak M. Patel, Tanner Buck, Anthony Huber, Eve M. Vavagiakis, James Burgoyne, Scott Chapman, Ben Keller, Jenna E. Moore, Michael D. Niemack, CCAT Collaboration

Abstract: Prime-Cam is a first-generation instrument for the Fred Young Submillimeter Telescope (FYST), enabling wide-field, multi-frequency observations for cosmology, line-intensity mapping, and galaxy studies. We present an optical performance study for a candidate 410 GHz broadband module designed to field approximately 21,000 polarisation-sensitive kinetic inductance detectors (KIDs). The three-lens si… ▽ More Prime-Cam is a first-generation instrument for the Fred Young Submillimeter Telescope (FYST), enabling wide-field, multi-frequency observations for cosmology, line-intensity mapping, and galaxy studies. We present an optical performance study for a candidate 410 GHz broadband module designed to field approximately 21,000 polarisation-sensitive kinetic inductance detectors (KIDs). The three-lens silicon design was adapted from the SO LATR design and used for the existing 280 and 350 GHz Prime-Cam instrument modules, as well as this study. At 410 GHz, a shorter wavelength places tighter demands on wavefront quality and beam shape. Using Ansys Zemax OpticStudio and Huygens PSF analysis, we evaluate candidate module positions, compare 350 and 410 GHz performance, and assess field-dependent Strehl ratio, ellipticity, and encircled-energy behaviour. A preliminary tolerancing study, using inverse increment and Monte Carlo methods, tests sensitivity to selected alignment perturbations. △ Less

Submitted 21 August, 2026; v1 submitted 3 August, 2026; originally announced August 2026.

Comments: 17 pages, 7 figures, SPIE Astronomical Telescopes + Instrumentation 2026

Blowup of Multi-Peaked Waveforms in the Two-Dimensional Nonlinear Schroedinger Model

Authors: S. Jon Chapman, M. Kavousanakis, E. G. Charalampidis, I. G. Kevrekidis, P. G. Kevrekidis

Abstract: In the present work, we explore the self-focusing and resulting collapse of two-dimensional waveforms involving multiple pulses in a nonlinear Schroedinger equation with a general power-law nonlinearity. We find that a wide range of multi-peaked states bifurcate from the critical threshold of the cubic nonlinearity, thus representing ``bifurcations from infinity'', i.e., the relevant pulses start… ▽ More In the present work, we explore the self-focusing and resulting collapse of two-dimensional waveforms involving multiple pulses in a nonlinear Schroedinger equation with a general power-law nonlinearity. We find that a wide range of multi-peaked states bifurcate from the critical threshold of the cubic nonlinearity, thus representing ``bifurcations from infinity'', i.e., the relevant pulses start at infinite distance in the critical limit and draw nearer, as the nonlinearity exponent increases past that threshold. We identify the resulting ``interacting particle system'' as amounting to a force balance between the exponentially interacting tails (modulated by a suitable power law) and a linear phase-induced force. The equilibria emerging from this force balance are found to be in excellent agreement with the identified steady states of the partial differential equation. The spectral stability of multi-peaked configurations is analyzed, leading to the conclusion that all the relevant states are less stable than the single-peak collapsing solution whose stability was analyzed earlier. Indeed, we reveal both symmetry-breaking, as well as motion-inducing destabilizing dynamics, with the former ones among them being dominant and ultimately leading to a single dominant collapse spot. Moreover, we characterize systematically both the real and imaginary eigenvalues of multi-peaked configurations, partitioning them in groups of different sizes, described by powers of the solution's blowup rate G. △ Less

Submitted 28 July, 2026; originally announced July 2026.

Assessing the large-scale angular clustering of UNIONS Lyman Break Galaxies via cross-correlations

Authors: Constantin Payerne, Christophe Yèche, William d'Assignies Doumerg, Hendrik Hildebrandt, Martin Kilbinger, Calum Murray, Thomas de Boer, Kenneth C. Chambers, Scott Chapman, Alan W. McConnachie

Abstract: Lyman-break galaxies (LBGs), selected via the strong spectral break blueward of the Lyman limit, are powerful tracers of large-scale structure at redshifts $z>2$. In this work, we assess the feasibility of using LBGs selected from the Ultraviolet Near Infrared Optical Northern Survey (UNIONS) multi-band photometric catalog as cosmological probes of the high-redshift Universe using two-point statis… ▽ More Lyman-break galaxies (LBGs), selected via the strong spectral break blueward of the Lyman limit, are powerful tracers of large-scale structure at redshifts $z>2$. In this work, we assess the feasibility of using LBGs selected from the Ultraviolet Near Infrared Optical Northern Survey (UNIONS) multi-band photometric catalog as cosmological probes of the high-redshift Universe using two-point statistics. We demonstrate that spatially varying imaging systematics, driven by variations in PSF depth, seeing across the UNIONS footprint, limit robust measurements of the LBG auto-angular power spectrum on large scales, even after correcting the LBG field with linear or non-linear mitigation techniques. This study shows that clustering analyses of faint galaxy samples close to survey depth are challenging. We therefore turn to cross-correlation measurements with external tracers, in particular the \textit{Planck} CMB lensing convergence and quasars from DESI DR1 and \textit{Quaia}, which are less sensitive to the angular imaging systematics. Using both data and mock catalogues, we demonstrate that the LBG--CMB lensing cross-power spectrum can be measured more robustly than the auto-spectrum, with an amplitude consistent with theoretical predictions. Residual systematics primarily manifest as excess variance at large angular scales, without introducing a significant bias in the recovered signal. Taken together, these results establish UNIONS-selected LBGs as reliable tracers for cross-correlation cosmology at $z\sim 2.5$, and highlight cross-correlation techniques as a powerful and robust avenue for extracting cosmological information from photometric high-redshift galaxy samples in the presence of complex imaging systematics. △ Less

Submitted 15 July, 2026; v1 submitted 10 July, 2026; originally announced July 2026.

Comments: 20 pages, 19 figures, to be submitted to The Open Journal of Astrophysics

Benchmarking Vision-Language Models for Microscopic Plant Image Understanding

Authors: Tianqi Wei, Xin Yu, Zhi Chen, Scott Chapman, Zi Huang

Abstract: Microscopic imaging provides essential visual evidence for studying plant biology and pathology at the cellular and subcellular levels. However, existing benchmarks on vision-language models primarily focus on macroscopic plant imagery, while the microscopic domain remains underexplored. To address this gap, we present PlantMicro, a comprehensive benchmark for evaluating vision-language models (VL… ▽ More Microscopic imaging provides essential visual evidence for studying plant biology and pathology at the cellular and subcellular levels. However, existing benchmarks on vision-language models primarily focus on macroscopic plant imagery, while the microscopic domain remains underexplored. To address this gap, we present PlantMicro, a comprehensive benchmark for evaluating vision-language models (VLMs) in microscopic plant imagery. PlantMicro integrates more than 5,000 images collected across diverse hosts, biological domains, and imaging modalities. Building on this diversity, we design a set of complementary tasks that capture different facets of microscopic image understanding. To support these tasks, we construct over 9,000 VQA pairs that systematically evaluate the capabilities of VLMs. Experiments on PlantMicro show that current VLMs struggle with fine-grained recognition and biologically grounded reasoning. For example, GPT-5 achieves 34.93% accuracy on the pathogen classification task, which is only modestly above the random-guessing baseline. The results highlight a significant gap in current VLMs' ability to comprehend plant microscopic images. PlantMicro provides a standardized foundation for advancing VLMs toward reliable and comprehensive microscopy-level plant understanding. △ Less

Submitted 24 June, 2026; v1 submitted 21 June, 2026; originally announced June 2026.

An extreme ram-pressure stripping event in a protocluster at redshift 4.3

Authors: Dazhi Zhou, Scott C. Chapman, Manuel Aravena, Roger Deane, Anthony H. Gonzalez, Ryley Hill, Nicholas LeVar, Matthew A. Malkan, Adam Muzzin, Nan Zhang, Kedar A. Phadke, Vismaya R. Pillai, Manuel Solimano, Justin S. Spilker, Nikolaus Sulzenauer, Joaquin D. Vieira, David Vizgan, George C. P. Wang, Axel Weiss

Abstract: In the nearby Universe, the environment plays a crucial role in suppressing star formation in dense regions. In particular, ram-pressure stripping (RPS) is a major mechanism for removing gas from galaxies in clusters, occurring when galaxies travel through a dense hot atmosphere and leave trailing gaseous wakes. By depleting the cold gas reservoir, RPS can drive outside-in quenching and is therefo… ▽ More In the nearby Universe, the environment plays a crucial role in suppressing star formation in dense regions. In particular, ram-pressure stripping (RPS) is a major mechanism for removing gas from galaxies in clusters, occurring when galaxies travel through a dense hot atmosphere and leave trailing gaseous wakes. By depleting the cold gas reservoir, RPS can drive outside-in quenching and is therefore thought to be an important route for transforming cluster galaxies. At earlier times, however, protoclusters are dynamically young and their hot atmospheres are expected to be immature, so environmental effects are commonly assumed to be dominated by gravitational interactions rather than hydrodynamic stripping. Recent observations have begun to show that RPS can already operate before mature cluster assembly, including extended gas tails in a forming cluster at $z=2.51$ and in a galaxy group at $z=3.06$. These studies demonstrate that hydrodynamic stripping is possible at earlier times, but whether RPS can become sufficient enough to quench massive galaxies at $z>2$ remains unclear. Here we report ALMA and JWST observations of SPT2349$-$56-C26, a massive galaxy experiencing an extreme RPS event in the SPT2349$-$56 protocluster at $z=4.30$. C26 appears to exhibit a particularly severe active-stripping phase: the displaced gas contains more than half of the observed cold-gas reservoir, with the gas-emission peak showing a large 6-kpc offset from the stellar body. These observations show that RPS can remove most of the cold gas from massive galaxies in dense protocluster cores as early as $z=4.3$, providing a direct hydrodynamic pathway for environmental quenching at $z>4$. △ Less

Submitted 16 June, 2026; originally announced June 2026.

Comments: 3 main figures, 9 Extended Data figures, and 4 Extended Data tables; 42 pages total

It's Not Just Star Formation: A trend of low dark matter densities in the Andromeda dwarf galaxy system

Authors: Connor S. Pickett, Michelle L. M. Collins, Justin I. Read, R. Michael Rich, Emily J. E. Charles, Erik Tollerud, Nicolas Martin, Scott Chapman, Alan McConnachie, Alessandro Savino, Daniel R. Weisz

Abstract: Dynamical mass modeling of Andromeda (M31) dwarf spheroidal (dSph) galaxies has revealed a growing trend of lower central dark matter (DM) densities than predicted by pure DM structure formation in Lambda Cold Dark Matter ($Λ$CDM) cosmology simulations and lower than most Milky Way (MW) satellites. So far, however, only four of the 35 confirmed M31 dSphs have been successfully mass modeled. In thi… ▽ More Dynamical mass modeling of Andromeda (M31) dwarf spheroidal (dSph) galaxies has revealed a growing trend of lower central dark matter (DM) densities than predicted by pure DM structure formation in Lambda Cold Dark Matter ($Λ$CDM) cosmology simulations and lower than most Milky Way (MW) satellites. So far, however, only four of the 35 confirmed M31 dSphs have been successfully mass modeled. In this second paper of a series, we aim to better understand growing Local Group (LG) dSph patterns by mass modeling seven more M31 dSphs: Andromeda I, III, V, VII, IX, XXXI, and XXXII. We update the kinematics of each dwarf and estimate their central dark matter densities at 150 pc using the dynamical Jeans modeling tool, GravSphere. We also update their DM halo mass, $M_{\rm{200}}$, via abundance matching. We find Andromeda III and V to have central DM densities in line with $Λ$CDM expectations, resembling dSphs around the Milky Way. The remaining five dwarfs have anomalously low central densities, continuing a growing trend seen for M31 satellites. We investigate each dwarf's star formation history and find that star formation-induced `DM heating' is disfavored as the sole explanation of these lower central densities. We consider the effect of tides and halo concentration scatter on these systems and predict that they should be on more plunging orbits than their denser counterparts. If this prediction is misaligned with the data, it could necessitate new physics beyond the Standard Cosmological Model. △ Less

Submitted 29 May, 2026; originally announced June 2026.

Comments: 21 pages, 14 Figures; Submitted to MNRAS

CCAT: Silicon-Platelet Feedhorns for Submillimeter Wavelengths

Authors: Jason Austermann, James Beall, James R. Burgoyne, Scott Chapman, Steve Choi, Cody J. Duell, Anthony I. Huber, Johannes Hubmayr, Matthew A. Koc, Michael D. Niemack, Joel N. Ullom, Jeffrey van Lanen, Anna Vaskuri, Michael Vissers, Jordan Wheeler

Abstract: Silicon-platelet feedhorn arrays are an established technology at millimeter wavelengths that, for some applications, can provide significant advantages over traditional direct-machined metal feedhorns. The Prime-Cam focal planes operating in the 350 GHz ($\sim$860 $\mathrmμ$m) and 850 GHz ($\sim$350 $\mathrmμ$m) bands are anticipated to carry the first silicon-platelet feedhorn arrays to operate… ▽ More Silicon-platelet feedhorn arrays are an established technology at millimeter wavelengths that, for some applications, can provide significant advantages over traditional direct-machined metal feedhorns. The Prime-Cam focal planes operating in the 350 GHz ($\sim$860 $\mathrmμ$m) and 850 GHz ($\sim$350 $\mathrmμ$m) bands are anticipated to carry the first silicon-platelet feedhorn arrays to operate fully at submillimeter wavelengths, representing a significant step forward in the application of this technology. In particular, the feedhorns designed for operation in the 850 GHz band represent a 3x increase in frequency compared to previously demonstrated and deployed devices of this type. Here we present a demonstration of silicon-platelet feedhorns at these submillimeter wavelengths, including in-lab performance characterization. We present fabrication metrology, room-temperature beammaps, and cryogenic optical efficiency measurements where the feedhorns are coupled to prototype CCAT Prime-Cam detectors. We show that feedhorn performance measurements are well matched to simulation and compare that performance directly to traditional, direct-machined metal feedhorns. △ Less

Submitted 23 April, 2026; originally announced April 2026.

Comments: 9 pages, 9 figures. Special issue of IEEE Transactions on Applied Superconductivity for proceedings of the 2025 Low Temperature Detectors (LTD) conference

A tensor invariant approach to energy flux in magnetohydrodynamic turbulence

Authors: Conan M. Liptrott, Sandra C. Chapman, Bogdan Hnat, Nicholas W. Watkins

Abstract: A scale-by-scale analysis of energy flux in the turbulent cascade can be performed using the spatially filtered magnetohydrodynamic (MHD) equations, while the gradient tensor invariants are widely used to characterize the structure of velocity and magnetic fields. Physical mechanisms responsible for energy flux require specific field configurations whose strength is quantified by these tensor inva… ▽ More A scale-by-scale analysis of energy flux in the turbulent cascade can be performed using the spatially filtered magnetohydrodynamic (MHD) equations, while the gradient tensor invariants are widely used to characterize the structure of velocity and magnetic fields. Physical mechanisms responsible for energy flux require specific field configurations whose strength is quantified by these tensor invariants. We explore this requirement, showing that the tensor invariants act as proxies for mechanistic energy fluxes under quantifiable conditions. As a special case, the purely hydrodynamic contributions to energy flux can be expressed exactly in terms of the invariants of the velocity gradient tensor. We also show that the invariants bound the available energy flux for distinct physical mechanisms, formalizing the idea that each transfer mechanism requires field configurations with gradients of sufficient strength to support a given energy flux. Results are illustrated using three-dimensional simulations of freely decaying MHD turbulence. These findings advance our understanding of MHD turbulence by revealing key relationships between field topology and energy transfer across scales due to distinct physical mechanisms. They further provide a tool for probing the turbulent cascade using multispacecraft data where local tensor invariants are directly accessible. △ Less

Submitted 16 August, 2026; v1 submitted 15 April, 2026; originally announced April 2026.

Journal ref: Phys. Rev. E 114, 025102 2026

Learning to Synergize Semantic and Geometric Priors for Limited-Data Wheat Disease Segmentation

Authors: Shijie Wang, Zijian Wang, Yadan Luo, Scott Chapman, Xin Yu, Zi Huang

Abstract: Wheat disease segmentation is fundamental to precision agriculture but faces severe challenges from significant intra-class temporal variations across growth stages. Such substantial appearance shifts make collecting a representative dataset for training from scratch both labor-intensive and impractical. To address this, we propose SGPer, a Semantic-Geometric Prior Synergization framework that tre… ▽ More Wheat disease segmentation is fundamental to precision agriculture but faces severe challenges from significant intra-class temporal variations across growth stages. Such substantial appearance shifts make collecting a representative dataset for training from scratch both labor-intensive and impractical. To address this, we propose SGPer, a Semantic-Geometric Prior Synergization framework that treats wheat disease segmentation under limited data as a coupled task of disease-specific semantic perception and disease boundary localization. Our core insight is that pretrained DINOv2 provides robust category-aware semantic priors to handle appearance shifts, which can be converted into coarse spatial prompts to guide SAM for the precise localization of disease boundaries. Specifically, SGPer designs disease-sensitive adapters with multiple disease-friendly filters and inserts them into both DINOv2 and SAM to align their pretrained representations with disease-specific characteristics. To operationalize this synergy, SGPer transforms DINOv2-derived features into dense, category-specific point prompts to ensure comprehensive spatial coverage of all disease regions. To subsequently eliminate prompt redundancy and ensure highly accurate mask generation, it dynamically filters these dense candidates by cross-referencing SAM's iterative mask confidence with the category-specific semantic consistency derived from DINOv2. Ultimately, SGPer distills a highly informative set of prompts to activate SAM's geometric priors, achieving precise and robust segmentation that remains strictly invariant to temporal appearance changes. Extensive evaluations demonstrate that SGPer consistently achieves state-of-the-art performance on wheat disease and organ segmentation benchmarks, especially in data-constrained scenarios. △ Less

Submitted 7 April, 2026; originally announced April 2026.

Discovery of a nearby radio relic in the low-mass, merging cluster Abell 4067

Authors: Isaac Magolego, Roger P. Deane, Kshitij Thorat, Ian Heywood, Justin Spilker, Taweewat Somboonpanyakul, Dazhi Zhou, Manuel Aravena, Joaquin D. Vieira, Kedar A. Phadke, Lindsey E. Bleem, Scott C. Chapman

Abstract: Shock waves generated during cluster mergers offer a powerful probe of how large-scale structure grows and evolves in the Universe. As part of the MeerKAT-South Pole Telescope (SPT) survey, we report the discovery of a single arc-like radio relic in the galaxy cluster Abell 4067 ($z=0.099$), one of the lowest-mass clusters known to host such a structure. MeerKAT UHF-band (0.58--1.09 GHz) observati… ▽ More Shock waves generated during cluster mergers offer a powerful probe of how large-scale structure grows and evolves in the Universe. As part of the MeerKAT-South Pole Telescope (SPT) survey, we report the discovery of a single arc-like radio relic in the galaxy cluster Abell 4067 ($z=0.099$), one of the lowest-mass clusters known to host such a structure. MeerKAT UHF-band (0.58--1.09 GHz) observations reveal a relic with a largest linear size of $\sim 1.48 \pm 0.02$ Mpc, located at a projected distance of 0.95 Mpc from the cluster centre. XMM-Newton X-ray data show that the relic's position and orientation relative to the intracluster medium (ICM) elongation are consistent with a merger-driven shock-wave scenario. The relic has an estimated radio power of $3.10 \pm 0.03 \times 10^{24}$ W Hz$^{-1}$ at 150 MHz. When placed in the $P_{150\,\mathrm{MHz}}$--$M_{500}$ scaling relation, the Abell 4067 relic appears less luminous compared to relics in more massive clusters, suggesting an association with weak merger shocks. This finding supports the idea that relics in low-mass clusters may form through less energetic merger events, leading to weak merger shocks. This is further supported by the absence of a detectable central radio halo in Abell 4067, reinforcing the idea that luminous radio halos are not a universal outcome of cluster mergers and highlighting the role of cluster mass, merger energetics, and evolutionary stage in shaping diffuse radio emission in the intracluster medium. △ Less

Submitted 27 February, 2026; originally announced February 2026.

Comments: 8 pages, 3 figures, 2 tables. Submitted to MNRAS Letters

StomataSeg: Semi-Supervised Instance Segmentation for Sorghum Stomatal Components

Authors: Zhongtian Huang, Zhi Chen, Zi Huang, Xin Yu, Daniel Smith, Chaitanya Purushothama, Erik Van Oosterom, Alex Wu, William Salter, Yan Li, Scott Chapman

Abstract: Sorghum is a globally important cereal grown widely in water-limited and stress-prone regions. Its strong drought tolerance makes it a priority crop for climate-resilient agriculture. Improving water-use efficiency in sorghum requires precise characterisation of stomatal traits, as stomata control of gas exchange, transpiration and photosynthesis have a major influence on crop performance. Automat… ▽ More Sorghum is a globally important cereal grown widely in water-limited and stress-prone regions. Its strong drought tolerance makes it a priority crop for climate-resilient agriculture. Improving water-use efficiency in sorghum requires precise characterisation of stomatal traits, as stomata control of gas exchange, transpiration and photosynthesis have a major influence on crop performance. Automated analysis of sorghum stomata is difficult because the stomata are small (often less than 40 $μ$m in length in grasses such as sorghum) and vary in shape across genotypes and leaf surfaces. Automated segmentation contributes to high-throughput stomatal phenotyping, yet current methods still face challenges related to nested small structures and annotation bottlenecks. In this paper, we propose a semi-supervised instance segmentation framework tailored for analysis of sorghum stomatal components. We collect and annotate a sorghum leaf imagery dataset containing 11,060 human-annotated patches, covering the three stomatal components (pore, guard cell and complex area) across multiple genotypes and leaf surfaces. To improve the detection of tiny structures, we split high-resolution microscopy images into overlapping small patches. We then apply a pseudo-labelling strategy to unannotated images, producing an additional 56,428 pseudo-labelled patches. Benchmarking across semantic and instance segmentation models shows substantial performance gains: for semantic models the top mIoU increases from 65.93% to 70.35%, whereas for instance models the top AP rises from 28.30% to 46.10%. These results demonstrate that combining patch-based preprocessing with semi-supervised learning significantly improves the segmentation of fine stomatal structures. The proposed framework supports scalable extraction of stomatal traits and facilitates broader adoption of AI-driven phenotyping in crop science. △ Less

Submitted 31 January, 2026; originally announced February 2026.

Fully Turbulent Wakes at Low Reynolds Numbers: the Case of the Thin Flat Plate

Authors: Isaac T. Rosin, Melanie S. Chapman, Bartosz Protas, Robert J. Martinuzzi

Abstract: We consider the wake flow past a thin two-dimensional flat plate normal to the uniform stream and demonstrate that this flow is turbulent already at a relatively low Reynolds number of $Re = 400$. This is achieved by performing a careful comparison of the results of a DNS of this flow with experimental measurements of wake flows in the same geometric configuration at the Reynolds numbers of… ▽ More We consider the wake flow past a thin two-dimensional flat plate normal to the uniform stream and demonstrate that this flow is turbulent already at a relatively low Reynolds number of $Re = 400$. This is achieved by performing a careful comparison of the results of a DNS of this flow with experimental measurements of wake flows in the same geometric configuration at the Reynolds numbers of $Re=12500, 19700$. This comparison reveals that the distribution of several key quantities, including the mean velocity, Reynolds stresses and different effects contributing to the transport of the turbulent kinetic energy, are, up to measurement uncertainty, the same in these flows. Moreover, the wake flow at $Re = 400$ also features energy spectra characteristic of turbulent flows with intermittency detected in the distributions of the fluctuating strain and rotation rates. In contrast, these features are absent from the results of the DNS of the wake flow at $Re = 150$ where the distribution of the key quantities is also fundamentally different. These results show that the path to transition to turbulence in the wake past a thin flat plate is different from that in the wakes of canonical (i.e., circular or square) cylinders. We also identify possible physical mechanisms that may be responsible for these differences. △ Less

Submitted 24 January, 2026; originally announced January 2026.

Comments: 36 pages, 22 figures, submitted to Journal of Turbulence

Primate-like perceptual decision making emerges through deep recurrent reinforcement learning

Authors: Nathan J. Wispinski, Scott A. Stone, Anthony Singhal, Patrick M. Pilarski, Craig S. Chapman

Abstract: Progress has led to a detailed understanding of the neural mechanisms that underlie decision making in primates. However, less is known about why such mechanisms are present in the first place. Theory suggests that primate decision making mechanisms, and their resultant behavioral abilities, emerged to maximize reward in the face of noisy, temporally evolving information. To test this theory, we t… ▽ More Progress has led to a detailed understanding of the neural mechanisms that underlie decision making in primates. However, less is known about why such mechanisms are present in the first place. Theory suggests that primate decision making mechanisms, and their resultant behavioral abilities, emerged to maximize reward in the face of noisy, temporally evolving information. To test this theory, we trained an end-to-end deep recurrent neural network using reinforcement learning on a noisy perceptual discrimination task. Networks learned several key abilities of primate-like decision making including trading off speed for accuracy, and flexibly changing their mind in the face of new information. Internal dynamics of these networks suggest that these abilities were supported by similar decision mechanisms as those observed in primate neurophysiological studies. These results provide experimental support for key pressures that gave rise to the primate ability to make flexible decisions. △ Less

Submitted 18 January, 2026; originally announced January 2026.

A census of star-formation and gas mass tracers in two lensed $z \sim 4$ dusty star-forming galaxies

Authors: David Vizgan, Joaquin D. Vieira, Justin S. Spilker, Simon Birrer, Nan Zhang, Manuel Aravena, Melanie A. Archipley, Jack E. Birkin, Jared Cathey, Scott C. Chapman, Veronica J. Dike, Anthony H. Gonzalez, Thomas R. Greve, Gayathri Gururajan, Ryley Hill, Matthew A. Malkan, Desika Narayanan, Kedar A. Phadke, Vismaya Pillai, Ana C. Posses, Manuel Solimano, Nikolaus Sulzenauer, Dazhi Zhou

Abstract: We present new and archival Atacama Large Millimeter/submillimeter Array (ALMA) observations of two strongly lensed dusty star-forming galaxies (DSFGs) selected from the South Pole Telescope survey, SPT0418-47 $(z = 4.225)$ and SPT2147-50 $(z = 3.760)$. We study the [C II], CO(7-6), [C I](2-1), and, in SPT0418-47, $p$-H$_2$O emission, which along with the underlying continuum (rest-frame 160 $μ$m… ▽ More We present new and archival Atacama Large Millimeter/submillimeter Array (ALMA) observations of two strongly lensed dusty star-forming galaxies (DSFGs) selected from the South Pole Telescope survey, SPT0418-47 $(z = 4.225)$ and SPT2147-50 $(z = 3.760)$. We study the [C II], CO(7-6), [C I](2-1), and, in SPT0418-47, $p$-H$_2$O emission, which along with the underlying continuum (rest-frame 160 $μ$m and 380 $μ$m) are routinely used as tracers of gas mass and/or star-formation rate (SFR). We perform a pixel-by-pixel analysis of both sources in the image plane to study the resolved Kennicutt-Schmidt relation, finding generally good agreement between the slopes of the SFR versus gas mass surface density using the different tracers. Using lens modeling methods, we find that the dust emission is more compact than the line emission in both sources, with CO(7-6) and [C I](2-1) similar in extent and [C II] the most extended, reminiscent of recent findings of extended [C II] spatial distributions in galaxies at similar cosmic epochs. We develop the [C I](2-1) / CO(7-6) flux density ratio as an observable proxy for gas depletion timescale ($τ_{\rm dep}$), which can be applied to large samples of DSFGs, in lieu of more detailed inferences of this timescale which require analysis of observations at multiple wavelengths. Furthermore, the extended [C II] emission in both sources, compared to the total continuum and line emission, suggests that [C II], used in recent years as a molecular gas mass and SFR tracer in high-$z$ galaxies, may not always be a suitable tracer of these physical quantities. △ Less

Submitted 7 January, 2026; originally announced January 2026.

Comments: 26 pages, 14 figures, 5 tables. Accepted for publication in ApJ

An Overabundance of Radio-AGN in the SPT2349-56 Protocluster: Preheating the Intra-Cluster Medium

Authors: Scott C. Chapman, Roger P. Deane, Dazhi Zhou, Manuel Aravena, William Rasakanya, Melanie Archipley, James Burgoyne, Jared Cathey, Anthony H. Gonzalez, Ryley Hill, Chayce Hughes, Monica Natalia Isla Llave, Matt Malkan, Kedar A. Phadke, Vismaya Pillai, Ana Posses, Bonnie Slocombe, Manuel Solimano, Justin Spilker, Nikolaus Sulzenauer, Fabio Vito, Joaquin D. Vieira, David Vizgan, George Wang, Axel Weiss

Abstract: Following the detection of a radio-loud Active Galactic Nucleus (AGN) in the z=4.3 protocluster SPT2349-56, we have obtained additional observations with MeerKAT in S-band (2.4 GHz) with the aim of further characterizing radio emission from amongst the ~30 submillimeter (submm) galaxies (SMGs) identified in the structure. We newly identify three of the protocluster SMGs individually at 2.4GHz as h… ▽ More Following the detection of a radio-loud Active Galactic Nucleus (AGN) in the z=4.3 protocluster SPT2349-56, we have obtained additional observations with MeerKAT in S-band (2.4 GHz) with the aim of further characterizing radio emission from amongst the ~30 submillimeter (submm) galaxies (SMGs) identified in the structure. We newly identify three of the protocluster SMGs individually at 2.4GHz as having a radio-excess, two of which are now known to be X-ray luminous AGN. Two additional members are also detected with radio emission consistent with their star formation rate (SFR). Archival MeerKAT UHF (816 MHz) observations further constrain luminosities and radio spectral indices of these five galaxies. The Australia Telescope Compact Array (ATCA) is used to detect and resolve the central two sources at 5.5 and 9.0 GHz finding elongated, jet-like morphologies. The excess radio luminosities range from L1.4,rest = (1-20)x10^25 W/Hz, ~10-100x higher than expected from the SFRs, assuming the usual far-infrared-radio correlation. Of the known cluster members, only the SMG `N1' shows signs of AGN in any other diagnostics, namely a large and compact excess in CO(11-10) line emission. We compare these results to field samples of radio sources and SMGs. The overdensity of radio-loud AGN in the compact core region of the cluster may be providing significant heating to the recently discovered nascent intra-cluster medium (ICM) in SPT2349-56. △ Less

Submitted 21 November, 2025; originally announced November 2025.

Comments: 15 pages, submitted to ApJ

Euclid Quick Data Release (Q1). The average far-infrared properties of Euclid-selected star-forming galaxies

Authors: Euclid Collaboration, R. Hill, A. Abghari, D. Scott, M. Bethermin, S. C. Chapman, D. L. Clements, S. Eales, A. Enia, B. Jego, A. Parmar, P. Tanouri, L. Wang, S. Andreon, N. Auricchio, C. Baccigalupi, M. Baldi, A. Balestra, S. Bardelli, P. Battaglia, A. Biviano, E. Branchini, M. Brescia, S. Camera, G. Cañas-Herrera , et al. (280 additional authors not shown)

Abstract: The first Euclid Quick Data Release contains millions of galaxies with excellent optical and near-infrared (IR) coverage. To complement this dataset, we investigate the average far-IR properties of Euclid-selected main sequence (MS) galaxies using existing Herschel and SCUBA-2 data. We use 17.6deg$^2$ (2.4deg$^2$) of overlapping Herschel (SCUBA-2) data, containing 2.6 million (240000) MS galaxies.… ▽ More The first Euclid Quick Data Release contains millions of galaxies with excellent optical and near-infrared (IR) coverage. To complement this dataset, we investigate the average far-IR properties of Euclid-selected main sequence (MS) galaxies using existing Herschel and SCUBA-2 data. We use 17.6deg$^2$ (2.4deg$^2$) of overlapping Herschel (SCUBA-2) data, containing 2.6 million (240000) MS galaxies. We bin the Euclid catalogue by stellar mass and photometric redshift and perform a stacking analysis following SimStack, which takes into account galaxy clustering and bin-to-bin correlations. We detect stacked far-IR flux densities across a significant fraction of the bins. We fit modified blackbody spectral energy distributions in each bin and derive mean dust temperatures, dust masses, and star-formation rates (SFRs). We find similar mean SFRs compared to the Euclid catalogue, and we show that the average dust-to-stellar mass ratios decreased from z$\simeq$1 to the present day. Average dust temperatures are largely independent of stellar mass and are well-described by the function $T_2+(T_1-T_2){\rm e}^{-t/τ}$, where $t$ is the age of the Universe, $T_1=79.7\pm7.4$K, $T_2=23.2\pm0.1$K, and $τ=1.6\pm0.1$Gyr. We argue that since the dust temperatures are converging to a non-zero value below $z=1$, the dust is now primarily heated by the existing cooler and older stellar population, as opposed to hot young stars in star-forming regions at higher redshift. We show that since the dust temperatures are independent of stellar mass, the correlation between dust temperature and SFR depends on stellar mass. Lastly, we estimate the contribution of the Euclid catalogue to the cosmic IR background (CIB), finding that it accounts for >60% of the CIB at 250, 350, and 500$μ$m. Forthcoming Euclid data will extend these results to higher redshifts, lower stellar masses, and recover more of the CIB. △ Less

Submitted 10 July, 2026; v1 submitted 4 November, 2025; originally announced November 2025.

Comments: Submitted to A&A as part of the second Euclid Q1 paper splash. V2 fixed typo in title. V3 accepted by A&A. V4 fixed typo in Table B.1

A Weakly Nonlinear Theory for Pattern Formation in Structured Models with Localized Solutions

Authors: Wesley J. M. Ridgway, Mohit P. Dalwadi, Philip Pearce, S. Jonathan Chapman

Abstract: Structured models, such as PDEs structured by age or phenotype, provide a setting to study pattern formation in heterogeneous populations. Classical tools to quantify the emergence of patterns, such as linear and weakly nonlinear analyses, pose significant mathematical challenges for these models due to sharply peaked or singular steady states. Here, we present a weakly nonlinear framework that ex… ▽ More Structured models, such as PDEs structured by age or phenotype, provide a setting to study pattern formation in heterogeneous populations. Classical tools to quantify the emergence of patterns, such as linear and weakly nonlinear analyses, pose significant mathematical challenges for these models due to sharply peaked or singular steady states. Here, we present a weakly nonlinear framework that extends classical tools to structured PDE models in settings where the base state is spatially uniform, but exponentially localized in the structured variable. Our approach utilizes WKBJ asymptotics and an analysis of the Stokes phenomenon to systematically resolve the solution structure in the limit where the steady state tends to a Dirac-delta function. To demonstrate our method, we consider a chemically structured (nonlocal) model of motile bacteria that interact through quorum sensing. For this example, our analysis yields an amplitude equation that governs the solution dynamics near a linear instability, and predicts a pitchfork bifurcation. From the amplitude equation, we deduce an effective parameter grouping whose sign determines whether the pitchfork bifurcation is subcritical or supercritical. Although we demonstrate our framework for a specific example, our techniques are broadly applicable. △ Less

Submitted 23 October, 2025; originally announced October 2025.

Report number: PIMS-20251022-PDF MSC Class: 35B36 (Primary); 35B25; 35B32; 35C20; 34E20; 34M40 (Secondary)

CCAT: Optical Responsivity, Noise, and Readout Optimization of KIDs for Prime-Cam

Authors: Eliza Gazda, Quintin Meyers, Steve K. Choi, James R. Burgoyne, Scott Chapman, Cody J. Duell, Anthony I. Huber, Inchara Jagadeesh, David Faulkner Katz, Ben Keller, Lawrence T. Lin, Paul Malachuk, Michael D. Niemack, Darshan A. Patel, Gordon J. Stacey, Benjamin J. Vaughan, Eve M. Vavagiakis, Samantha Walker, Yuhan Wang, Ruixuan, Xie

Abstract: The Prime-Cam instrument on the Fred Young Submillimeter Telescope (FYST) at the CCAT Observatory will conduct sensitive millimeter to submillimeter surveys for a range of astrophysical and cosmological sciences. Prime-Cam will use kinetic inductance detectors (KIDs) sensitive to multiple frequency bands spanning 280-850 GHz. With over 100,000 sensors under development, these KID arrays will soon… ▽ More The Prime-Cam instrument on the Fred Young Submillimeter Telescope (FYST) at the CCAT Observatory will conduct sensitive millimeter to submillimeter surveys for a range of astrophysical and cosmological sciences. Prime-Cam will use kinetic inductance detectors (KIDs) sensitive to multiple frequency bands spanning 280-850 GHz. With over 100,000 sensors under development, these KID arrays will soon form the largest submillimeter focal plane ever built. With fixed microwave tones probing amplitude and phase modulations in the KIDs due to incoming radiation, challenges arise in determining the optimal readout settings, especially under varying atmospheric loading. Realizing the science goals of FYST requires operating the detectors at optimal performance and determining accurate responsivities, which depend on readout tone placement and power. To address these challenges, we present laboratory measurements of sample pixels from the 280 GHz TiN and Al arrays using a blackbody cold load to simulate observing conditions. These measurements probe detector responsivity and noise across varying optical loading, tone power, and tone placement, providing the foundation to guide in situ calibration and operation of the >100,000 KIDs. We characterize detector sensitivity via the Noise Equivalent Power (NEP) as a function of readout tone power and placement, and measure the impact of detuning due to varying optical power on the NEP. Our test setup and methodology will inform the commissioning of Prime-Cam, in situ detector calibration procedures, the cadence of probe tone resetting, and potential design refinements for future arrays, supporting FYST's planned first light in 2026. △ Less

Submitted 21 July, 2026; v1 submitted 14 October, 2025; originally announced October 2025.

Comments: This is the published version

Journal ref: IEEE Transactions on Applied Superconductivity (2026)

CCAT: Design, Implementation, and Testing of a System to Read Out over 10,000 280 GHz KIDs using RFSoC Electronics

Authors: Darshan A. Patel, Yuhan Wang, Cody J. Duell, Jason E. Austermann, James Beall, James R. Burgoyne, Scott Chapman, Steve K. Choi, Rodrigo G. Freundt, Eliza Gazda, Christopher Groppi, Zachary B. Huber, Johannes Hubmayr, Ben Keller, Lawrence T. Lin, Philip Mauskopf, Alicia Middleton, Michael D. Niemack, Cody Roberson, Adrian K. Sinclair, Ema Smith, Jeff van Lanen, Anna Vaskuri, Benjamin J. Vaughan, Eve M. Vavagiakis , et al. (5 additional authors not shown)

Abstract: Over the past decade, kinetic inductance detectors (KIDs) have emerged as a viable superconducting technology for astrophysics at millimeter and submillimeter wavelengths. KIDs spanning 210 - 850 GHz across seven instrument modules will be deployed in the Prime-Cam instrument of CCAT Observatory's Fred Young Submillimeter Telescope at an elevation of 5600 m on Cerro Chajnantor in Chile's Atacama D… ▽ More Over the past decade, kinetic inductance detectors (KIDs) have emerged as a viable superconducting technology for astrophysics at millimeter and submillimeter wavelengths. KIDs spanning 210 - 850 GHz across seven instrument modules will be deployed in the Prime-Cam instrument of CCAT Observatory's Fred Young Submillimeter Telescope at an elevation of 5600 m on Cerro Chajnantor in Chile's Atacama Desert. The natural frequency-division multiplexed readout of KIDs allows hundreds of detectors to be coupled to a single radio frequency (RF) transmission line, but requires sophisticated warm readout electronics. The FPGA-based Xilinx ZCU111 radio frequency system on chip (RFSoC) offers a promising and flexible solution to the challenge of warm readout. CCAT uses custom packaged RFSoCs to read out KIDs in the Prime-Cam instrument. Each RFSoC can simultaneously read out four RF channels with up to 1,000 detectors spanning a 512 MHz bandwidth per channel using the current firmware. We use five RFSoCs to read out the >10,000 KIDs in the broadband 280 GHz instrument module. Here, we describe and demonstrate the readout hardware, software and pipeline for the RFSoC system. We present a detector position map of the 280 GHz module focal plane and preliminary averaged spectral responses of a small subset of detectors from the TiN and first Al arrays. These measurements demonstrate our ability to simultaneously readout thousands of detectors, validate the end-to-end performance of the readout and optical systems, and represent a critical step toward reading out the ~100,000 KIDs in Prime-Cam in its future full capacity configuration. △ Less

Submitted 6 August, 2026; v1 submitted 7 October, 2025; originally announced October 2025.

Comments: 8 pages, 8 figures, accepted to IEEE Transactions on Applied Superconductivity, Special Issue for Low Temperature Detectors 2025 Conference

CCAT: Magnetic Sensitivity Measurements of Kinetic Inductance Detectors

Authors: Benjamin J. Vaughan, Yuhan Wang, Cody J. Duell, Jason Austermann, James R. Burgoyne, Scott Chapman, Steve K. Choi, Abigail T. Crites, Eliza Gazda, Ben Keller, Michael D. Niemack, Darshan A. Patel, Anna Vaskuri, Eve M. Vavagiakis, Michael Vissers, Samantha Walker, Jordan Wheeler, Ruixuan, Xie

Abstract: The CCAT Observatory is a ground-based submillimeter to millimeter experiment located on Cerro Chajnantor in the Atacama Desert, at an altitude of 5,600 meters. CCAT features the 6-meter Fred Young Submillimeter Telescope (FYST), which will cover frequency bands from 210 GHz to 850 GHz using its first-generation science instrument, Prime-Cam. The detectors used in Prime-Cam are feedhorn-coupled, l… ▽ More The CCAT Observatory is a ground-based submillimeter to millimeter experiment located on Cerro Chajnantor in the Atacama Desert, at an altitude of 5,600 meters. CCAT features the 6-meter Fred Young Submillimeter Telescope (FYST), which will cover frequency bands from 210 GHz to 850 GHz using its first-generation science instrument, Prime-Cam. The detectors used in Prime-Cam are feedhorn-coupled, lumped-element superconducting microwave kinetic inductance detectors (KIDs). The telescope will perform wide-area surveys at speeds on the order of degrees per second. During telescope operation, the KIDs are exposed to changes in the magnetic field caused by the telescope's movement through Earth's magnetic field and internal sources within the telescope. We present and compare measurements of the magnetic sensitivity of three different CCAT KID designs at 100 mK. The measurements are conducted in a dilution refrigerator (DR) with a set of room temperature Helmholtz coils positioned around the DR. We discuss the implications of these results for CCAT field operations. △ Less

Submitted 15 February, 2026; v1 submitted 3 October, 2025; originally announced October 2025.

CCAT: Mod-Cam Readout Overview and Flexible Stripline Performance

Authors: Ben Keller, Rodrigo Freundt, James R. Burgoyne, Scott Chapman, Steve Choi, Cody J. Duell, Christopher Groppi, Caleb Humphreys, Lawrence T. Lin, Alicia Middleton, Michael D. Niemack, Darshan Patel, Eve Vavagiakis, Samantha Walker, Yuhan Wang, Ruixuan, Xie

Abstract: The CCAT Observatory's primary science instrument, Prime-Cam, is nearing readiness for deployment to the Fred Young Submillimeter Telescope (FYST) in the Atacama Desert in northern Chile. When fully deployed, Prime-Cam will field approximately 100,000 kinetic inductance detectors (KIDs) across seven instrument modules making both broadband and polarimetric measurements. Meanwhile, in-lab character… ▽ More The CCAT Observatory's primary science instrument, Prime-Cam, is nearing readiness for deployment to the Fred Young Submillimeter Telescope (FYST) in the Atacama Desert in northern Chile. When fully deployed, Prime-Cam will field approximately 100,000 kinetic inductance detectors (KIDs) across seven instrument modules making both broadband and polarimetric measurements. Meanwhile, in-lab characterization of the first CCAT instrument module, a 280 GHz broadband camera fielding over 10,000 KIDs, is currently underway in the testbed instrument Mod-Cam. Both Mod-Cam and Prime-Cam will employ 46 cm long low-thermal-conductivity flexible circuits ("stripline") between 4 K and 300 K to connect large-format arrays of multiplexed KIDs in each instrument module to readout electronics. The 280 GHz camera currently installed in Mod-Cam uses six of these striplines to read out its over 10,000 detectors. We have examined the thermal and electrical performance of the stripline installed in Mod-Cam. We begin by characterizing the OFHC copper in the stripline traces, allowing for the estimation of thermal loading through these flexible circuits in their configurations in both Mod-Cam and Prime-Cam. We then directly measure the thermal conductivity of the stripline, finding it is best described by $kA = 22\pm6~T^{0.84\pm0.09}~\mathrm{μ~W~m~K^{-1}}$ for temperature ranges of 6 K < T < 20 K and $kA~=~0.6\pm0.3~T^{-0.4\pm0.1}~\mathrm{mW~m~K^{-1}}$ for ranges from 20 K < T < 80 K. Following our thermal characterizations, we report on the transmission and crosstalk properties of the Mod-Cam readout chain, isolating elevated crosstalk to SMP-SMA transition printed circuit boards (PCBs) that interface with the stripline. This finding validates the stripline circuit as a viable high-density cabling option for large-format array readout. △ Less

Submitted 27 February, 2026; v1 submitted 29 September, 2025; originally announced September 2025.

Comments: 6 pages, 7 figures, submitted to LTD 2025 conference proceedings

CCAT: Mod-Cam Cryogenic Performance and its Impact on 280 GHz KID Array Noise

Authors: Lawrence T. Lin, Eve M. Vavagiakis, Jason E. Austermann, James R. Burgoyne, Scott Chapman, Steve K. Choi, Abigail T. Crites, Cody J. Duell, Rodrigo G. Freundt, Eliza Gazda, Christopher Groppi, Anthony I. Huber, Zachary B. Huber, Johannes Hubmayr, Ben Keller, Philip Mauskopf, Alicia Middleton, Michael D. Niemack, Darshan A. Patel, Cody Roberson, Adrian K. Sinclair, Ema Smith, Anna Vaskuri, Benjamin J. Vaughan, Samantha Walker , et al. (5 additional authors not shown)

Abstract: The CCAT Observatory's Fred Young Submillimeter Telescope (FYST) is designed to observe submillimeter astronomical signals with high precision, using receivers fielding state-of-the-art kinetic inductance detector (KID) arrays. Mod-Cam, a first-light instrument for FYST, serves as a testbed for instrument module characterization, including detailed evaluation of thermal behavior under operating co… ▽ More The CCAT Observatory's Fred Young Submillimeter Telescope (FYST) is designed to observe submillimeter astronomical signals with high precision, using receivers fielding state-of-the-art kinetic inductance detector (KID) arrays. Mod-Cam, a first-light instrument for FYST, serves as a testbed for instrument module characterization, including detailed evaluation of thermal behavior under operating conditions prior to deploying modules in the larger Prime-Cam instrument. Prime-Cam is a first generation multi-band, wide-field camera for FYST, designed to field up to seven instrument modules and provide unprecedented sensitivity across a broad frequency range. We present results from two key laboratory characterizations: an "optically open" cooldown to validate the overall thermal performance of the cryostat, and a "cold load" cooldown to measure the effect of focal plane temperature stability on detector noise. During the optically open test, we achieved stable base temperatures of 1.5 K on the 1 K stage and 85 mK at the detector stage. In the cold load configuration, we measured a detector focal plane RMS temperature stability of 3.2e-5 K. From this stability measurement, we demonstrate that the equivalent power from focal plane thermal fluctuations is only 0.0040% of a 5pW incident photon power for aluminum detectors and 0.0023% for titanium-nitride detectors, a negligible level for CCAT science goals. This highlights the success of the cryogenic system design and thermal management. △ Less

Submitted 29 September, 2025; originally announced September 2025.

Comments: 7 pages, 8 figures, Low temperature detector 2025 proceeding submitted to IEEE Transactions on Applied Superconductivity

Dynamic Orchestration of Multi-Agent System for Real-World Multi-Image Agricultural VQA

Authors: Yan Ke, Xin Yu, Heming Du, Scott Chapman, Helen Huang

Abstract: Agricultural visual question answering is essential for providing farmers and researchers with accurate and timely knowledge. However, many existing approaches are predominantly developed for evidence-constrained settings such as text-only queries or single-image cases. This design prevents them from coping with real-world agricultural scenarios that often require multi-image inputs with complemen… ▽ More Agricultural visual question answering is essential for providing farmers and researchers with accurate and timely knowledge. However, many existing approaches are predominantly developed for evidence-constrained settings such as text-only queries or single-image cases. This design prevents them from coping with real-world agricultural scenarios that often require multi-image inputs with complementary views across spatial scales, and growth stages. Moreover, limited access to up-to-date external agricultural context makes these systems struggle to adapt when evidence is incomplete. In addition, rigid pipelines often lack systematic quality control. To address this gap, we propose a self-reflective and self-improving multi-agent framework that integrates four roles, the Retriever, the Reflector, the Answerer, and the Improver. They collaborate to enable context enrichment, reflective reasoning, answer drafting, and iterative improvement. A Retriever formulates queries and gathers external information, while a Reflector assesses adequacy and triggers sequential reformulation and renewed retrieval. Two Answerers draft candidate responses in parallel to reduce bias. The Improver refines them through iterative checks while ensuring that information from multiple images is effectively aligned and utilized. Experiments on the AgMMU benchmark show that our framework achieves competitive performance on multi-image agricultural QA. △ Less

Submitted 29 September, 2025; originally announced September 2025.

Comments: 13 pages, 2 figures, 2 tables

Large-order perturbation theory of linear eigenvalue problems

Authors: Stephen Jonathan Chapman

Abstract: We consider a class of linear eigenvalue problems depending on a small parameter epsilon in which the series expansion for the eigenvalue in powers of epsilon is divergent. We develop a new technique to determine the precise nature of this divergence. We illustrate the technique through its application to four examples: the anharmonic oscillator, a simplified model of equatorially-trapped Rossby w… ▽ More We consider a class of linear eigenvalue problems depending on a small parameter epsilon in which the series expansion for the eigenvalue in powers of epsilon is divergent. We develop a new technique to determine the precise nature of this divergence. We illustrate the technique through its application to four examples: the anharmonic oscillator, a simplified model of equatorially-trapped Rossby waves, and two simplified models based on quasinormal modes of Reissner-Nordstrom-de Sitter black holes. △ Less

Submitted 3 February, 2026; v1 submitted 18 September, 2025; originally announced September 2025.

Comments: 5 figures

MSC Class: 34E05 (Primary); 34E15; 34E20; 81-10 (Secondary)

Augment to Segment: Tackling Pixel-Level Imbalance in Wheat Disease and Pest Segmentation

Authors: Tianqi Wei, Xin Yu, Zhi Chen, Scott Chapman, Zi Huang

Abstract: Accurate segmentation of foliar diseases and insect damage in wheat is crucial for effective crop management and disease control. However, the insect damage typically occupies only a tiny fraction of annotated pixels. This extreme pixel-level imbalance poses a significant challenge to the segmentation performance, which can result in overfitting to common classes and insufficient learning of rare… ▽ More Accurate segmentation of foliar diseases and insect damage in wheat is crucial for effective crop management and disease control. However, the insect damage typically occupies only a tiny fraction of annotated pixels. This extreme pixel-level imbalance poses a significant challenge to the segmentation performance, which can result in overfitting to common classes and insufficient learning of rare classes, thereby impairing overall performance. In this paper, we propose a Random Projected Copy-and-Paste (RPCP) augmentation technique to address the pixel imbalance problem. Specifically, we extract rare insect-damage patches from annotated training images and apply random geometric transformations to simulate variations. The transformed patches are then pasted in appropriate regions while avoiding overlaps with lesions or existing damaged regions. In addition, we apply a random projection filter to the pasted regions, refining local features and ensuring a natural blend with the new background. Experiments show that our method substantially improves segmentation performance on the insect damage class, while maintaining or even slightly enhancing accuracy on other categories. Our results highlight the effectiveness of targeted augmentation in mitigating extreme pixel imbalance, offering a straightforward yet effective solution for agricultural segmentation problems. △ Less

Submitted 12 September, 2025; originally announced September 2025.

Discovery of a $z \sim 0.8$ Ultra Steep Spectrum Radio Halo in the MeerKAT-South Pole Telescope Survey

Authors: Isaac S. Magolego, Roger P. Deane, Kshitij Thorat, Ian Heywood, William Rasakanya, Manuel Aravena, Lindsey E. Bleem, Maria G. Campitiello, Kedar A. Phadke, Justin Spilker, Joaquin D. Vieira, Dazhi Zhou, Bradford A. Benson, Scott Chapman, Ana Posses, Tim Schrabback, Anthony Stark, David Vizgan

Abstract: Radio halos are diffuse synchrotron sources that trace the turbulent intracluster medium (ICM) of galaxy clusters. However, their origin remains unknown. Two main formation models have been proposed: the hadronic model, in which relativistic electrons are continuously injected by cosmic-ray protons; and the leptonic turbulent re-acceleration model, where cluster mergers re-energise electrons in si… ▽ More Radio halos are diffuse synchrotron sources that trace the turbulent intracluster medium (ICM) of galaxy clusters. However, their origin remains unknown. Two main formation models have been proposed: the hadronic model, in which relativistic electrons are continuously injected by cosmic-ray protons; and the leptonic turbulent re-acceleration model, where cluster mergers re-energise electrons in situ. A key discriminant between the two models would be the existence of ultra-steep spectrum radio halos (USSRHs), which can only be produced through turbulent re-acceleration. Here we report the discovery of an USSRH in the galaxy cluster SPT-CLJ2337$-$5942 at redshift $z = 0.78$ in the MeerKAT-South Pole Telescope 100 deg$^2$ survey. This discovery is noteworthy for two primary reasons: it is the highest redshift USSRH system to date; and the close correspondence of the radio emission with the thermal ICM as traced by $\mathit{Chandra}$ X-ray observations, further supporting the leptonic re-acceleration model. The halo is under-luminous for its mass, consistent with a minor merger origin, which produces steep-spectrum, lower luminosity halos. This result demonstrates the power of wide-field, high-fidelity, $\lesssim1$ GHz surveys like the MeerKAT-SPT 100 deg$^2$ programme to probe the origin and evolution of radio halos over cosmic time, ahead of the Square Kilometre Array. △ Less

Submitted 9 September, 2025; originally announced September 2025.

Comments: 8 pages, 4 figures, 2 tables. Submitted to MNRAS Letters

Bright [CII]158$μ$m Streamers as a Beacon for Giant Galaxy Formation in SPT2349$-$56 at $z=4.3$

Authors: Nikolaus Sulzenauer, Axel Weiß, Ryley Hill, Scott C. Chapman, Manuel Aravena, Veronica J. Dike, Anthony Gonzalez, Duncan MacIntyre, Desika Narayanan, Kedar A. Phadke, Vismaya R. Pillai, Ana C. Posses, Douglas Rennehan, Amelie Saintonge, Justin S. Spilker, Manuel Solimano, Joel Tsuchitori, Joaquin D. Vieira, David Vizgan, Dazhi Zhou

Abstract: Observations of extreme starbursts, often located in the cores of protoclusters, challenge the classical bottom-up galaxy formation paradigm. Giant elliptical galaxies at $z=0$ must have assembled rapidly, possibly within few 100 Myr through an extreme growth phase at high-redshift, characterized by elevated star-formation rates of several thousand solar masses per year distributed over concurrent… ▽ More Observations of extreme starbursts, often located in the cores of protoclusters, challenge the classical bottom-up galaxy formation paradigm. Giant elliptical galaxies at $z=0$ must have assembled rapidly, possibly within few 100 Myr through an extreme growth phase at high-redshift, characterized by elevated star-formation rates of several thousand solar masses per year distributed over concurrent, gas-rich mergers. We present a novel view of the $z=4.3$ protocluster core SPT2349$-$56 from sensitive multi-cycle ALMA dust continuum and [CII]158$μ$m line observations. Distributed across 60 kpc, a highly structured gas reservoir with a line luminosity of $L_\mathrm{[CII]}=3.0\pm0.2\times10^9$ $L_\odot$ and an inferred cold gas mass of $M_{gas}= 8.9\pm0.7\times10^{9}$ $M_\odot$ is found surrounding the central massive galaxy triplet. Like ``beads on a string'', the newly-discovered [CII] streamers fragment into a few kpc-spaced and turbulent clumps that have a similar column density as local Universe spiral galaxy arms at $Σ_{gas}=20$--$60$ $M_\odot$ pc$^{-2}$. For a dust temperature of 30 K, the [CII] emission from the ejected clumps carry $\gtrsim$3% of the FIR luminosity, translating into an exceptionally low mass-to-light ratio of $α_\mathrm{[CII]}=2.95\pm0.3$ $M_\odot$ $L_\odot^{-1}$, indicative of shock-heated molecular gas. In phase space, about half of the galaxies in the protocluster core populate the same caustic as the [CII] streamers ($r/r_{vir}\times|Δv|/σ_{vir}\approx0.1$), suggesting angular momentum dissipation via tidal ejection while the brightest cluster galaxy (BCG) is assembling. Our findings provide new evidence for the importance of tidal ejections of [CII]-bright, shocked material following multiple major mergers that might represent a landmark phase in the $z\gtrsim4$ co-evolution of BCGs with their hot, metal enriched atmospheres. △ Less

Submitted 9 September, 2025; originally announced September 2025.

Comments: 31 pages, 12 figures, 5 tables. Submitted to ApJ

Small-time asymptotics and the emergence of complex singularities for the KdV equation

Authors: Scott W. McCue, Christopher J. Lustri, Daniel J. VandenHeuvel, Jocelyn Zhang, John R. King, S. Jonathan Chapman

Abstract: While real-valued solutions of the Korteweg--de Vries (KdV) equation have been studied extensively over the past 50 years, much less attention has been devoted to solution behaviour in the complex plane. Here we consider the analytic continuation of real solutions of KdV and investigate the role that complex-plane singularities play in early-time solutions on the real line. We apply techniques of… ▽ More While real-valued solutions of the Korteweg--de Vries (KdV) equation have been studied extensively over the past 50 years, much less attention has been devoted to solution behaviour in the complex plane. Here we consider the analytic continuation of real solutions of KdV and investigate the role that complex-plane singularities play in early-time solutions on the real line. We apply techniques of exponential asymptotics to derive the small-time behaviour for dispersive waves that propagate in one direction, and demonstrate how the amplitude, wavelength and speed of these waves depend on the strength and location of double-pole singularities of the initial condition in the complex plane. Using matched asymptotic expansions in the limit $t\rightarrow 0^+$, we show how complex singularities of the time-dependent solution of the KdV equation emerge from these double-pole singularities. Generically, their speed as they move from their initial position is of $\mathcal{O}(t^{-2/3})$, while the direction in which these singularities propagate initially is dictated by a Painlevé II (P$_{\mathrm{II}}$) problem with decreasing tritronquée solutions. The well-known $N$-soliton solutions of KdV correspond to rational solutions of P$_{\mathrm{II}}$ with a finite number of singularities; otherwise, we postulate that infinitely many complex-plane singularities of KdV solutions are born at each double-pole singularity of the initial condition. We also provide asymptotic results for some non-generic cases in which singularities propagate more slowly than in the generic case. Our study makes progress towards the goal of providing a complete description of KdV solutions in the complex plane and, in turn, of relating this behaviour to the solution on the real line. △ Less

Submitted 25 February, 2026; v1 submitted 9 September, 2025; originally announced September 2025.

Journal ref: Journal of Nonlinear Waves (2026)

FoMo4Wheat: Toward reliable crop vision foundation models with globally curated data

Authors: Bing Han, Chen Zhu, Dong Han, Rui Yu, Songliang Cao, Jianhui Wu, Scott Chapman, Zijian Wang, Bangyou Zheng, Wei Guo, Marie Weiss, Benoit de Solan, Andreas Hund, Lukas Roth, Kirchgessner Norbert, Andrea Visioni, Yufeng Ge, Wenjuan Li, Alexis Comar, Dong Jiang, Dejun Han, Fred Baret, Yanfeng Ding, Hao Lu, Shouyang Liu

Abstract: Vision-driven field monitoring is central to digital agriculture, yet models built on general-domain pretrained backbones often fail to generalize across tasks, owing to the interaction of fine, variable canopy structures with fluctuating field conditions. We present FoMo4Wheat, one of the first crop-domain vision foundation model pretrained with self-supervision on ImAg4Wheat, the largest and mos… ▽ More Vision-driven field monitoring is central to digital agriculture, yet models built on general-domain pretrained backbones often fail to generalize across tasks, owing to the interaction of fine, variable canopy structures with fluctuating field conditions. We present FoMo4Wheat, one of the first crop-domain vision foundation model pretrained with self-supervision on ImAg4Wheat, the largest and most diverse wheat image dataset to date (2.5 million high-resolution images collected over a decade at 30 global sites, spanning >2,000 genotypes and >500 environmental conditions). This wheat-specific pretraining yields representations that are robust for wheat and transferable to other crops and weeds. Across ten in-field vision tasks at canopy and organ levels, FoMo4Wheat models consistently outperform state-of-the-art models pretrained on general-domain dataset. These results demonstrate the value of crop-specific foundation models for reliable in-field perception and chart a path toward a universal crop foundation model with cross-species and cross-task capabilities. FoMo4Wheat models and the ImAg4Wheat dataset are publicly available online: https://github.com/PheniX-Lab/FoMo4Wheat and https://huggingface.co/PheniX-Lab/FoMo4Wheat. The demonstration website is: https://fomo4wheat.phenix-lab.com/. △ Less

Submitted 8 September, 2025; originally announced September 2025.

A large thermal energy reservoir in the nascent intracluster medium at a redshift of 4.3

Authors: Dazhi Zhou, Scott Chapman, Manuel Aravena, Pablo Araya-Araya, Melanie Archipley, Jared Cathey, Roger Deane, Luca Di Mascolo, Raphael Gobat, Thomas Greve, Ryley Hill, Seonwoo Kim, Kedar Phadke, Vismaya Pillai, Ana Posses, Christian Reichardt, Manuel Solimano, Justin Spilker, Nikolaus Sulzenauer, Veronica Dike, Joaquin Vieira, David Vizgan, George Wang, Axel Weiss

Abstract: Most baryons in present-day galaxy clusters exist as hot gas ($\boldsymbol{\gtrsim10^7\,\rm}\mathrm{K}$), forming the intracluster medium (ICM). Cosmological simulations predict that the mass and temperature of the ICM rapidly decrease with increasing cosmological redshift, as intracluster gas in younger clusters is still accumulating and being heated. The thermal Sunyaev-Zeldovich (tSZ) effect ar… ▽ More Most baryons in present-day galaxy clusters exist as hot gas ($\boldsymbol{\gtrsim10^7\,\rm}\mathrm{K}$), forming the intracluster medium (ICM). Cosmological simulations predict that the mass and temperature of the ICM rapidly decrease with increasing cosmological redshift, as intracluster gas in younger clusters is still accumulating and being heated. The thermal Sunyaev-Zeldovich (tSZ) effect arises when cosmic microwave background (CMB) photons are scattered to higher energies through interactions with energetic electrons in hot ICM, leaving a localized decrement in the CMB at a long wavelength. The depth of this decrement is a measure of the thermal energy and pressure of the gas. To date, the effect has been detected in only three systems at or above $z\sim2$, when the Universe was 4 billion years old, making the time and mechanism of ICM assembly uncertain. Here, we report observations of this effect in the protocluster SPT2349$-$56 with Atacama Large Millimeter/submillimeter Array (ALMA). SPT2349$-$56 contains a large molecular gas reservoir, with at least 30 dusty star-forming galaxies (DSFGs) and three radio-loud active galactic nuclei (AGN) in a 100-kpc region at $z=4.3$, corresponding to 1.4 billion years after the Big Bang. The observed tSZ signal implies a thermal energy of $\mathbf{\sim 10^{61}\,\mathrm{erg}}$, exceeding the possible energy of a virialized ICM by an order of magnitude. Contrary to current theoretical expectations, the strong tSZ decrement in SPT2349$-$56 demonstrates that substantial heating can occur and deposit a large amount of thermal energy within growing galaxy clusters, overheating the nascent ICM in unrelaxed structures, two billion years before the first mature clusters emerged at $\mathbf{z \sim 2}$. △ Less

Submitted 4 September, 2025; originally announced September 2025.

Comments: 49 pages, 12 figures, 4 tables. Original submission before addressing reviewers' comments, as requested by the journal guidelines

An Image-Plane Approach to Gravitational Lens Modeling of Interferometric Data

Authors: Nan Zhang, Sreevani Jarugula, Justin S. Spilker, Simon Birrer, Jared Cathey, Scott C. Chapman, Veronica J. Dike, Anthony H. Gonzalez, Gilbert Holder, Kedar A. Phadke, Cassie Reuter, Joaquin D. Vieira, David Vizgan, Dazhi Zhou

Abstract: Strong gravitational lensing acts as a cosmic telescope, enabling the study of the high-redshift universe. Astronomical interferometers, such as the Atacama Large Millimeter/submillimeter Array (ALMA), have provided high-resolution images of strongly lensed sources at millimeter and submillimeter wavelengths. To model the mass and light distributions of lensing and source galaxies from strongly le… ▽ More Strong gravitational lensing acts as a cosmic telescope, enabling the study of the high-redshift universe. Astronomical interferometers, such as the Atacama Large Millimeter/submillimeter Array (ALMA), have provided high-resolution images of strongly lensed sources at millimeter and submillimeter wavelengths. To model the mass and light distributions of lensing and source galaxies from strongly lensed images, strong lens modeling for interferometric observations is conventionally performed in the visibility space, which is computationally expensive. In this paper, we implement an image-plane lens modeling methodology for interferometric dirty images by accounting for noise correlations. We show that the image-plane likelihood function produces accurate model values when tested on simulated ALMA observations with an ensemble of noise realizations. We also apply our technique to ALMA observations of two sources selected from the South Pole Telescope survey, comparing our results with previous visibility-based models. Our model results are consistent with previous models for both parametric and pixelated source-plane reconstructions. We implement this methodology for interferometric lens modeling in the open-source software package lenstronomy. △ Less

Submitted 26 August, 2025; v1 submitted 11 August, 2025; originally announced August 2025.

Comments: 24 pages, 9 figures

CFT Complexity and Penalty Factors

Authors: Stefano Baiguera, Nicolas Chagnet, Shira Chapman, Osher Shoval

Abstract: Quantum complexity of conformal field theory (CFT) states has recently gained significant attention, both as a diagnostic tool in condensed matter systems and in connection with holographic observables probing black hole interiors. Previous studies have primarily focused on cases where all generators of the conformal group contribute equally to the cost of building a circuit. In this work, we pres… ▽ More Quantum complexity of conformal field theory (CFT) states has recently gained significant attention, both as a diagnostic tool in condensed matter systems and in connection with holographic observables probing black hole interiors. Previous studies have primarily focused on cases where all generators of the conformal group contribute equally to the cost of building a circuit. In this work, we present a general framework for studying the complexity of circuits in generic Lie groups, where penalty factors assign relative weights to different generators. Our approach constructs a metric on the coset space of quantum states, induced from a (pseudo-)Riemannian norm on the space of unitary circuits. The geodesics of this metric are interpreted as optimal circuits. The method builds on the formalism of (pseudo-)Riemannian submersions and connects naturally to other prescriptions in the literature, including cost function minimization along stabilizer directions and constructions based on coadjoint orbits. As a concrete application, we compute state complexity for states in one- and two-dimensional CFTs. For specific choices of penalty factors, our prescription yields a positive-definite metric with a viable interpretation as complexity; in other cases, the resulting metric is indefinite. In the viable regime, we derive analytic results when a specific penalty factor is turned off, develop perturbative expansions for small values of the penalty factors, and provide numerical results in the general case. We comment on the relation of our measure of complexity to holography. △ Less

Submitted 29 July, 2025; originally announced July 2025.

Comments: 46+18 pages, 10 figures

On the axioms for a unique factorization domain

Authors: Scott T. Chapman, Jim Coykendall

Abstract: With the growing evolution of the theory of non-unique factorization in integral domains and monoids, the study of several variations to the classical unique factorization domain (or UFD) property have become popular in the literature. Using one of these variations, the length-factorial property, it can be shown that part of the standard classical axioms used in the definition of a UFD is essentia… ▽ More With the growing evolution of the theory of non-unique factorization in integral domains and monoids, the study of several variations to the classical unique factorization domain (or UFD) property have become popular in the literature. Using one of these variations, the length-factorial property, it can be shown that part of the standard classical axioms used in the definition of a UFD is essentially superfluous. △ Less

Submitted 8 July, 2025; v1 submitted 7 July, 2025; originally announced July 2025.

Comments: 10 pages

MSC Class: 13F15

Millimeter-wave observations of Euclid Deep Field South using the South Pole Telescope: A data release of temperature maps and catalogs

Authors: M. Archipley, A. Hryciuk, L. E. Bleem, K. Kornoelje, M. Klein, A. J. Anderson, B. Ansarinejad, M. Aravena, L. Balkenhol, P. S. Barry, K. Benabed, A. N. Bender, B. A. Benson, F. Bianchini, S. Bocquet, F. R. Bouchet, E. Camphuis, M. G. Campitiello, J. E. Carlstrom, J. Cathey, C. L. Chang, S. C. Chapman, P. Chaubal, P. M. Chichura, A. Chokshi , et al. (86 additional authors not shown)

Abstract: Context. The South Pole Telescope third-generation camera (SPT-3G) has observed over 10,000 square degrees of sky at 95, 150, and 220 GHz (3.3, 2.0, 1.4 mm, respectively) and will significantly overlap the ongoing 14,000 square-degree Euclid Wide Survey. The Euclid collaboration recently released Euclid Deep Field South (EDF-S) observations of 23 square degrees at wide field depths in the first qu… ▽ More Context. The South Pole Telescope third-generation camera (SPT-3G) has observed over 10,000 square degrees of sky at 95, 150, and 220 GHz (3.3, 2.0, 1.4 mm, respectively) and will significantly overlap the ongoing 14,000 square-degree Euclid Wide Survey. The Euclid collaboration recently released Euclid Deep Field South (EDF-S) observations of 23 square degrees at wide field depths in the first quick data release (Q1). Aims. With the goal of releasing complementary millimeter-wave data and encouraging legacy science, we performed dedicated observations of a 57-square-degree field overlapping the EDF-S. Methods. The observing time totaled 20 days, and we reached noise depths of 4.3, 3.8, and 13.2 $μ$K-arcmin at 95, 150, and 220 GHz, respectively. Results. In this work we present the temperature maps and two catalogs constructed from these data. The emissive source catalog contains 601 objects (334 inside EDF-S) with 54% synchrotron-dominated sources and 46% thermal dust emission-dominated sources. The 5$σ$ detection thresholds are 1.7, 2.0, and 6.5 mJy in the three bands. The cluster catalog contains 217 cluster candidates (121 inside EDF-S) with median mass $M_{500c}=2.12 \times 10^{14} M_{\odot}/h_{70}$ and median redshift $z$ = 0.70, corresponding to an order-of-magnitude improvement in cluster density over previous tSZ-selected catalogs in this region (3.81 clusters per square degree). Conclusions. The overlap between SPT and Euclid data will enable a range of multiwavelength studies of the aforementioned source populations. This work serves as the first step toward joint projects between SPT and Euclid and provides a rich dataset containing information on galaxies, clusters, and their environments. △ Less

Submitted 6 February, 2026; v1 submitted 30 May, 2025; originally announced June 2025.

Comments: 25 pages, 10 figures, published by A&A

Journal ref: A&A 706, A17 (2026)

Mass Modeling the Andromeda Dwarf Galaxies: Andromeda VI and Andromeda XXIII

Authors: Connor S. Pickett, Michelle L. M. Collins, R. Michael Rich, Justin I. Read, Emily J. E. Charles, Nicolas Martin, Scott Chapman, Alan McConnachie, Alessandro Savino, Daniel R. Weisz

Abstract: Accurately mapping the mass profiles of low mass dwarf spheroidal (dSph) galaxies allows us to test predictions made by dark matter (DM) models. To date, such analyses have primarily been performed on Milky Way (MW) satellites. Meanwhile, the Andromeda Galaxy (M31) is home to 35 known dwarf galaxies, yet only two have been successfully mass-modeled so far. A more comprehensive study of Local Group… ▽ More Accurately mapping the mass profiles of low mass dwarf spheroidal (dSph) galaxies allows us to test predictions made by dark matter (DM) models. To date, such analyses have primarily been performed on Milky Way (MW) satellites. Meanwhile, the Andromeda Galaxy (M31) is home to 35 known dwarf galaxies, yet only two have been successfully mass-modeled so far. A more comprehensive study of Local Group dwarfs is necessary to better understand the nature of dark matter. In this study, we have undertaken a dynamical study of two higher-luminosity Andromeda dwarf galaxies: Andromeda VI (And VI) and Andromeda XXIII (And XXIII). We infer an enclosed mass for And VI of M(r $<$ r$_{h}$) = (4.9 $\pm$ 1.5) $\times$ 10$^{7}$ M$_{\odot}$, corresponding to a mass-to-light ratio of $[M/L]_{r_{\rm{h}}}$ = (27.1 $\pm$ 8.2) M$_{\odot}$/L$_{\odot}$. We infer an enclosed mass for And XXIII of M(r $<$ r$_{h}$) = (3.1 $\pm$ 1.9) $\times$ 10$^{7}$ M$_{\odot}$, corresponding to a mass-to-light ratio of $[M/L]_{r_{\rm{h}}}$ = (90.2 $\pm$ 53.9) M$_{\odot}$/L$_{\odot}$. Using the dynamical Jeans modeling tool, \gravsphere, we determine And VI and And XXIII's dark matter density at 150 pc, finding $ρ_{\rm{DM,VI}}$(150 pc) = (1.4 $\pm$ 0.5) $\times 10^{8}$ M$_{\odot}$ kpc$^{-3}$ and $ρ_{\rm{DM,XXIII}}$(150 pc) = 0.5$\substack{+0.4 \\ -0.3} \times 10^{8}$ M$_{\odot}$ kpc$^{-3}$. Our results make And VI the first mass-modeled M31 satellite to fall into the cuspy regime. And XXIII has a lower density, implying either a more cored central dark matter density, or a lowering of the density through tides. This adds And XXIII to a growing list of M31 dwarfs with a central density lower than most MW dwarfs and lower than expected for isolated dwarfs in the Standard Cosmology. This could be explained by the M31 dwarfs having experienced stronger tides than their MW counterparts. △ Less

Submitted 19 May, 2025; v1 submitted 7 May, 2025; originally announced May 2025.

Comments: 19 pages, 16 figures. Accepted to MNRAS

Multi-hump Collapsing Solutions in the Nonlinear Schr{ö}dinger Problem: Existence, Stability and Dynamics

Authors: Jon S. Chapman, Mihalis Kavousanakis, Efstathios G. Charalampidis, Ioannis G. Kevrekidis, Panayotis G. Kevrekidis

Abstract: In the present work we examine multi-hump solutions of the nonlinear Schr{ö}dinger equation in the blowup regime of the one-dimensional model with power law nonlinearity, bearing a suitable exponent of $σ>2$. We find that families of such solutions exist for arbitrary pulse numbers, with all of them bifurcating from the critical case of $σ=2$. Remarkably, all of them involve ``bifurcations from in… ▽ More In the present work we examine multi-hump solutions of the nonlinear Schr{ö}dinger equation in the blowup regime of the one-dimensional model with power law nonlinearity, bearing a suitable exponent of $σ>2$. We find that families of such solutions exist for arbitrary pulse numbers, with all of them bifurcating from the critical case of $σ=2$. Remarkably, all of them involve ``bifurcations from infinity'', i.e., the pulses come inward from an infinite distance as the exponent $σ$ increases past the critical point. The position of the pulses is quantified and the stability of the waveforms is also systematically examined in the so-called ``co-exploding frame''. Both the equilibrium distance between the pulse peaks and the point spectrum eigenvalues associated with the multi-hump configurations are obtained as a function of the blowup rate $G$ theoretically, and these findings are supported by detailed numerical computations. Finally, some prototypical dynamical scenarios are explored, and an outlook towards such multi-hump solutions in higher dimensions is provided. △ Less

Submitted 13 April, 2025; originally announced April 2025.

Comments: 64 pages, 16 figures

Quantum complexity in gravity, quantum field theory, and quantum information science

Authors: Stefano Baiguera, Vijay Balasubramanian, Pawel Caputa, Shira Chapman, Jonas Haferkamp, Michal P. Heller, Nicole Yunger Halpern

Abstract: Quantum complexity quantifies the difficulty of preparing a state or implementing a unitary transformation with limited resources. Applications range from quantum computation to condensed matter physics and quantum gravity. We seek to bridge the approaches of these fields, which define and study complexity using different frameworks and tools. We describe several definitions of complexity, along w… ▽ More Quantum complexity quantifies the difficulty of preparing a state or implementing a unitary transformation with limited resources. Applications range from quantum computation to condensed matter physics and quantum gravity. We seek to bridge the approaches of these fields, which define and study complexity using different frameworks and tools. We describe several definitions of complexity, along with their key properties. In quantum information theory, we focus on complexity growth in random quantum circuits. In quantum many-body systems and quantum field theory (QFT), we discuss a geometric definition of complexity in terms of geodesics on the unitary group. In dynamical systems, we explore a definition of complexity in terms of state or operator spreading, as well as concepts from tensor-networks. We also outline applications to simple quantum systems, quantum many-body models, and QFTs including conformal field theories (CFTs). Finally, we explain the proposed relationship between complexity and gravitational observables within the holographic anti-de Sitter (AdS)/CFT correspondence. △ Less

Submitted 17 November, 2025; v1 submitted 13 March, 2025; originally announced March 2025.

Comments: 119 pages, including 14 figures. v1 of a review commissioned by Physics Reports. Suggestions and other comments are welcome. v2: references added, various sections extended. v3: version accepted and published on Physics Reports

Report number: YITP-25-39

Journal ref: Phys. Rept. 1159 (2026) 1-77

Betti elements and full atomic support in rings and monoids

Authors: Scott T. Chapman, Pedro García-Sánchez, Christopher O'Neill, Vadim Ponomarenko

Abstract: Several papers in the recent literature have studied factorization properties of affine monoids using the monoid's Betti elements. In this paper, we extend this study to more general rings and monoids. We open by demonstrating the issues with computing the complete set of Betti elements of a general commutative cancellative monoid, and as an example compute this set for an algebraic number ring of… ▽ More Several papers in the recent literature have studied factorization properties of affine monoids using the monoid's Betti elements. In this paper, we extend this study to more general rings and monoids. We open by demonstrating the issues with computing the complete set of Betti elements of a general commutative cancellative monoid, and as an example compute this set for an algebraic number ring of class number two. We specialize our study to the case where the monoid has a single Betti element, before examining monoids with full atomic support (that is, when each Betti element is divisible by every atom). For such a monoid, we show that the catenary degree, tame degree, and omega value agree and can be computed using the monoid's set of Betti elements. We close by considering Betti elements in block monoids, giving a "Carlitz-like" characterization of block monoids with full atomic support and proving that these are precisely the block monoids having a unique Betti element. △ Less

Submitted 10 March, 2025; v1 submitted 25 February, 2025; originally announced February 2025.

CCAT: Multi-Rate DSP for Sub-mm Astronomy: Polyphase Synthesis Filter Bank on FPGA for Enhanced MKID Readout

Authors: Ruixuan, Xie, Adrian K. Sinclair, James Burgoyne, Scott Chapman, Anthony Huber

Abstract: The next-generation mm/sub-mm/far-IR astronomy will in part be enabled by advanced digital signal processing (DSP) techniques. The Prime-Cam instrument of the Fred Young Submillimeter Telescope (FYST), featuring the largest array of submillimeter detectors to date, utilizes a novel overlap-channel polyphase synthesis filter bank (OC-PSB) for the AC biasing of detectors, implemented on a cutting-ed… ▽ More The next-generation mm/sub-mm/far-IR astronomy will in part be enabled by advanced digital signal processing (DSP) techniques. The Prime-Cam instrument of the Fred Young Submillimeter Telescope (FYST), featuring the largest array of submillimeter detectors to date, utilizes a novel overlap-channel polyphase synthesis filter bank (OC-PSB) for the AC biasing of detectors, implemented on a cutting-edge Xilinx Radio Frequency System on Chip (RFSoC). This design departs from traditional waveform look-up-table(LUT) in memory, allowing real-time, dynamic signal generation, enhancing usable bandwidth and dynamic range, and enabling microwave kinetic inductance detector (MKID) tracking for future readout systems. Results show that the OC-PSB upholds critical performance metrics such as signal-to-noise ratio (SNR) while offering additional benefits such as scalability. This paper will discuss DSP design, RFSoC implementation, and laboratory performance, demonstrating OC-PSB's potential in submillimeter-wave astronomy MKID readout systems. △ Less

Submitted 31 January, 2025; originally announced February 2025.

Comments: SPIE Astronomical Telescopes + Instrumentation conference proceedings 2024

Journal ref: Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XII, Proc. of SPIE (2024) Vol. 13102-1310213

Exponential Asymptotics for Translational Modes in the Discrete Nonlinear Schr{ö}dinger Model

Authors: C. J. Lustri, P. G. Kevrekidis, S. J. Chapman

Abstract: In the present work, we revisit the topic of translational eigenmodes in discrete models. We focus on the prototypical example of the discrete nonlinear Schr{ö}dinger equation, although the methodology presented is quite general. We tackle the relevant discrete system based on exponential asymptotics and start by deducing the well-known (and fairly generic) feature of the existence of two types of… ▽ More In the present work, we revisit the topic of translational eigenmodes in discrete models. We focus on the prototypical example of the discrete nonlinear Schr{ö}dinger equation, although the methodology presented is quite general. We tackle the relevant discrete system based on exponential asymptotics and start by deducing the well-known (and fairly generic) feature of the existence of two types of fixed points, namely site-centered and inter-site-centered. Then, turning to the stability problem, we not only retrieve the exponential scaling (as \( e^{-π^2/(2 \varepsilon)} \), where \( \varepsilon \) denotes the spacing between nodes) and its corresponding prefactor power-law (as \( \varepsilon^{-5/2} \)), both of which had been previously obtained, but we also obtain a highly accurate leading-order prefactor and, importantly, the next-order correction, for the first time, to the best of our knowledge. This methodology paves the way for such an analysis in a wide range of lattice nonlinear dynamical equation models. △ Less

Submitted 14 January, 2025; originally announced January 2025.

Comments: 17 pages, 3 figures

A Large Molecular Gas Reservoir in the Protocluster SPT2349$-$56 at $z\,{=}\,4.3$

Authors: Dazhi Zhou, Scott C. Chapman, Nikolaus Sulzenauer, Ryley Hill, Manuel Aravena, Pablo Araya-Araya, Jared Cathey, Daniel P. Marrone, Kedar A. Phadke, Cassie Reuter, Manuel Solimano, Justin S. Spilker, Joaquin D. Vieira, David Vizgan, George C. P. Wang, Axel Weiss

Abstract: We present Atacama Compact Array (ACA) Band-3 observations of the protocluster SPT2349$-$56, an extreme system hosting ${\gtrsim}\,12$ submillimeter galaxies (SMGs) at $z\,{=}\,4.3$, to study its integrated molecular gas content via CO(4-3) and long-wavelength dust continuum. The $\sim$30-hour integration represents one of the longest exposures yet taken on a single pointing with the ACA 7-m. The… ▽ More We present Atacama Compact Array (ACA) Band-3 observations of the protocluster SPT2349$-$56, an extreme system hosting ${\gtrsim}\,12$ submillimeter galaxies (SMGs) at $z\,{=}\,4.3$, to study its integrated molecular gas content via CO(4-3) and long-wavelength dust continuum. The $\sim$30-hour integration represents one of the longest exposures yet taken on a single pointing with the ACA 7-m. The low-resolution ACA data ($21.0''\,{\times}\,12.2''$) reveal a 75% excess CO(4-3) flux compared to the sum of individual sources detected in higher-resolution Atacama Large Millimeter Array (ALMA) data ($1.0''\,{\times}\,0.8''$). Our work also reveals a similar result by tapering the ALMA data to $10''$. In contrast, the 3.2mm dust continuum shows little discrepancy between ACA and ALMA. A single-dish [CII] spectrum obtained by APEX/FLASH supports the ACA CO(4-3) result, revealing a large excess in [CII] emission relative to ALMA. The missing flux is unlikely due to undetected faint sources but instead suggests that high-resolution ALMA observations might miss extended and low-surface-brightness gas. Such emission could originate from the circum-galactic medium (CGM) or the pre-heated proto-intracluster medium (proto-ICM). If this molecular gas reservoir replenishes the star formation fuel, the overall depletion timescale will exceed 400Myr, reducing the requirement for the simultaneous SMG activity in SPT2349$-$56. Our results highlight the role of an extended gas reservoir in sustaining a high star formation rate (SFR) in SPT2349$-$56, and potentially establishing the ICM during the transition phase to a mature cluster. △ Less

Submitted 17 March, 2025; v1 submitted 23 December, 2024; originally announced December 2024.

Comments: 14 pages, 6 figures and 3 tables. ApJL in press

Physics-based battery model parametrisation from impedance data

Authors: Noël Hallemans, Nicola E. Courtier, Colin P. Please, Brady Planden, Rishit Dhoot, Robert Timms, S. Jon chapman, David Howey, Stephen R. Duncan

Abstract: Non-invasive parametrisation of physics-based battery models can be performed by fitting the model to electrochemical impedance spectroscopy (EIS) data containing features related to the different physical processes. However, this requires an impedance model to be derived, which may be complex to obtain analytically. We have developed the open-source software PyBaMM-EIS that provides a fast method… ▽ More Non-invasive parametrisation of physics-based battery models can be performed by fitting the model to electrochemical impedance spectroscopy (EIS) data containing features related to the different physical processes. However, this requires an impedance model to be derived, which may be complex to obtain analytically. We have developed the open-source software PyBaMM-EIS that provides a fast method to compute the impedance of any PyBaMM model at any operating point using automatic differentiation. Using PyBaMM-EIS, we investigate the impedance of the single particle model, single particle model with electrolyte (SPMe), and Doyle-Fuller-Newman model, and identify the SPMe as a parsimonious option that shows the typical features of measured lithium-ion cell impedance data. We provide a grouped parameter SPMe and analyse the features in the impedance related to each parameter. Using the open-source software PyBOP, we estimate 18 grouped parameters both from simulated impedance data and from measured impedance data from a LG M50LT lithium-ion battery. The parameters that directly affect the response of the SPMe can be accurately determined and assigned to the correct electrode. Crucially, parameter fitting must be done simultaneously to data across a wide range of states-of-charge. Overall, this work presents a practical way to find the parameters of physics-based models. △ Less

Submitted 23 April, 2025; v1 submitted 14 December, 2024; originally announced December 2024.

Journal ref: Journal of the Electrochemical Society 172 (2025) 060507

Evidence for environmental effects in the $z\,{=}\,4.3$ protocluster core SPT2349$-$56

Authors: Chayce Hughes, Ryley Hill, Scott Chapman, Manuel Aravena, Melanie Archipley, Veronica J. Dike, Anthony Gonzalez, Thomas R. Greve, Gayathri Gururajan, Chris Hayward, Kedar Phadke, Cassie Reuter, Justin Spilker, Nikolaus Sulzenauer, Joaquin D. Vieira, David Vizgan, George Wang, Axel Weiss, Dazhi Zhou

Abstract: We present ALMA observations of the [CI] 492 and 806$\,$GHz fine-structure lines in 25 dusty star-forming galaxies (DSFGs) at $z\,{=}\,4.3$ in the core of the SPT2349$-$56 protocluster. The protocluster galaxies exhibit a median $L^\prime_{[\text{CI}](2-1)}/L^\prime_{[\text{CI}](1-0)}$ ratio of 0.94 with an interquartile range of 0.81-1.24. These ratios are markedly different to those observed in… ▽ More We present ALMA observations of the [CI] 492 and 806$\,$GHz fine-structure lines in 25 dusty star-forming galaxies (DSFGs) at $z\,{=}\,4.3$ in the core of the SPT2349$-$56 protocluster. The protocluster galaxies exhibit a median $L^\prime_{[\text{CI}](2-1)}/L^\prime_{[\text{CI}](1-0)}$ ratio of 0.94 with an interquartile range of 0.81-1.24. These ratios are markedly different to those observed in DSFGs in the field (across a comparable redshift and 850$\,μ$m flux density range), where the median is 0.55 with an interquartile range of 0.50-0.76, and we show that this difference is driven by an excess of [CI](2-1) in the protocluster galaxies for a given 850$\,μ$m flux density. Assuming local thermal equilibrium, we estimate gas excitation temperatures of $T_{\rm ex}\,{=}\,59.1^{+8.1}_{-6.8}\,$K for our protocluster sample and $T_{\rm ex}\,{=}\,33.9^{+2.4}_{-2.2}\,$K for the field sample. Our main interpretation of this result is that the protocluster galaxies have had their cold gas driven to their cores via close-by interactions within the dense environment, leading to an overall increase in the average gas density and excitation temperature, and an elevated [CI](2-1) luminosity-to-far-infrared luminosity ratio. △ Less

Submitted 1 May, 2025; v1 submitted 4 December, 2024; originally announced December 2024.

Journal ref: ApJL, 983, L11 (2025)

Some asymptotic results on $p$-lengths of factorizations for numerical semigroups and arithmetical congruence monoids

Authors: Spencer Chapman, Eli B. Dugan, Shadi Gaskari, Emi Lycan, Sarah Mendoza De La Cruz, Christopher O'Neill, Vadim Ponomarenko

Abstract: A factorization of an element $x$ in a monoid $(M, \cdot)$ is an expression of the form $x = u_1^{z_1} \cdots u_k^{z_k}$ for irreducible elements $u_1, \ldots, u_k \in M$, and the length of such a factorization is $z_1 + \cdots + z_k$. We introduce the notion of $p$-length, a generalized notion of factorization length obtained from the $\ell_p$-norm of the sequence $(z_1, \ldots, z_k)$, and presen… ▽ More A factorization of an element $x$ in a monoid $(M, \cdot)$ is an expression of the form $x = u_1^{z_1} \cdots u_k^{z_k}$ for irreducible elements $u_1, \ldots, u_k \in M$, and the length of such a factorization is $z_1 + \cdots + z_k$. We introduce the notion of $p$-length, a generalized notion of factorization length obtained from the $\ell_p$-norm of the sequence $(z_1, \ldots, z_k)$, and present asymptotic results on extremal $p$-lengths of factorizations for large elements of numerical semigroups (additive submonoids of $\mathbb Z_{\ge 0}$) and arithmetical congruence monoids (certain multiplicative submonoids of $\mathbb Z_{\ge 1}$). Our results, inspired by analogous results for classical factorization length, demonstrate the types of combinatorial statements one may hope to obtain for sufficiently nice monoids, as well as the subtlety such asymptotic questions can have for general monoids. △ Less

Submitted 25 November, 2024; originally announced November 2024.