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Physics Astrophysics

astro-ph Watch Astrophysics

Monday 15 December

Solar and Stellar Astrophysics

Unveiling the white dwarf in the eclipsing polar HU Aquarii

A.D. Schwope, T.R. Marsh, S.G. Parsons et al. (+2 more)

We present an analysis of high-speed u- and r-band photometry of the eclipsing polar HU Aquarii that was obtained with ULTRACAM mounted on the VLT. The observations were performed during a low state, permitting us for the first time to determine the contact points of the white dwarf. Using LCURVE we could determine its size, and hence mass, with a direct method and with unprecedented accuracy. We determined the mass of the white dwarf as 0.78 +- 0.02 Msun, the mass ratio Q= MWD / Msec = 4.59, and the orbital inclination i=87.4 +- 0.9. An extended warm region with a central temperature of ~33,000 K was observed in the u-band at the location of the previous high-state accretion spot. Weak accretion was ongoing in the low state that led to cyclotron emission that could best be studied with the r-band data. It has a diameter of only 3deg to 4deg and is located much closer to the binary meridian than the accretion-heated region studied in the u-band. The longitudinal shift of the two accretion regions is of order 30deg, due to early and late coupling of accreted matter onto the magnetic field lines in low and high accretion states, respectively. The low-state cyclotron-emitting region has a vertical extent of 0.005 - 0.016 Rwd, a value that seems to be correlated to the instantaneous accretion rate.
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All authors A.D. Schwope, T.R. Marsh, S.G. Parsons, J. Vogel, V.S. Dhillon

Instrumentation and Methods for Astrophysics

Resolving Galaxy Nuclei and Compact Stellar Systems as Engines of Galaxy Evolution

Julia Lamprecht, Izzy L. Garland, Daniel Jadlovsky et al. (+2 more)

In this white paper we focus on compact stellar systems, star clusters, nuclear star clusters (NSCs), stripped nuclei, and ultra-compact dwarfs (UCDs), as engines of galaxy evolution and black-hole growth. We show how the same capability also enables transformative science in active galactic nucleus (AGN) fuelling, stellar surfaces and interacting binaries, and exoplanet atmospheres. These science drivers are naturally aligned with a next-generation kilometre-scale optical/IR interferometer for the 2040s that reuses existing ESO infrastructure while adding diffraction-limited integral-field spectroscopy (IFS).
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All authors Julia Lamprecht, Izzy L. Garland, Daniel Jadlovsky, Jiri Zak, Tereza Jeřábková

Instrumentation and Methods for Astrophysics

Towards measuring astrophysical third order correlation functions with the H.E.S.S. optical intensity interferometer

Andreas Zmija, Gisela Anton, Christopher Ingenhuett et al. (+7 more)

The closure phase, the sum of the three Fourier phases in a telescope triangle, is an important tool in astronomical interferometry, helping to reconstruct the geometries of the observed objects. While already established in amplitude interferometry, for the recently expanding field of intensity interferometers the closure phase enables recovering information of the interferometric phases that are otherwise inaccessible with this technique. To extract the (cosine of) the closure phase ($\cos \phi$) in intensity interferometry, third-order correlations between three simultaneously measuring telescopes have to be computed. As the signal-to-noise of such three-photon correlations is too small for current generation intensity interferometers, no third-order correlations of astrophysical targets have been recorded so far. In this paper we present the first measurements of third order correlation functions of two stellar systems, Nunki ($\sigma $ Sgr) and Dschubba ($\delta$ Sco), observed with the H.E.S.S. intensity interferometer in 2023. We show how to isolate the three-photon contribution term from the two-photon contributions, in order to access $\cos \phi$. For the observed stellar targets the sensitivity is not high enough to extract closure phase information. To demonstrate that the analysis works well we further extract $\cos \phi$ in a laboratory experiment, using the H.E.S.S. intensity interferometer and a pseudo-thermal light source.
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All authors Andreas Zmija, Gisela Anton, Christopher Ingenhuett, Alison Mitchell, Prasenjit Saha, Pedro Silva Batista, Naomi Vogel, Adrian Zink, Robin Kaiser, Stefan Funk

Solar and Stellar Astrophysics

High Resolution Overtone Spectroscopy of HNC$^+$ and HCN$^+$

Miguel Jiménez-Redondo, Chiara Schleif, Julianna Palotás et al. (+5 more)

Rotationally resolved spectra of the HNC$^+$ and HCN$^+$ molecular ions have been recorded in the spectral range between 6200 and 6800 \rcm\ using a cryogenic ion trap instrument. The rovibrational transitions were probed using two different action spectroscopy schemes, namely laser-induced reaction (LIR) and leak-out spectroscopy (LOS). Various vibrational bands of HNC$^+$ and HCN$^+$ were measured with high resolution for the first time. For HNC$^+$, the $\text{X}~^2\Sigma^+~(20^00)-(00^00)$ overtone band was recorded using LIR, while LOS was used to probe the $\text{X}~^2\Pi~(000)^1-(210)^0\mu$ combination band and the $\text{X}~^2\Pi~(000)^1-\text{A}~^2\Sigma^+~(10^00)$ vibronic band of HCN$^+$. Spectroscopic constants, band origins and radiative lifetimes for the observed states have been determined. The effective fit for the HCN$^+$ spectra revealed the presence of strong vibrational couplings leading to perturbations of the rovibrational levels of the excited states. The two action spectroscopy schemes are compared and their potential use to explore ion-molecule interactions is discussed.
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All authors Miguel Jiménez-Redondo, Chiara Schleif, Julianna Palotás, János Sarka, Hayley Bunn, Petr Dohnal, Paola Caselli, Pavol Jusko

Solar and Stellar Astrophysics

The stellar to sub-stellar masses transition in 47 Tuc

C. Ventura, M. Tailo, P. Ventura et al. (+4 more)

Context: The study of the Globular Cluster 47 Tuc offers the opportunity to shed new light on the debated issue on the presence of multiple populations in Globular Clusters, as recent results from HST photometry and high-resolution spectroscopy outlined star-to-star differences in the surface chemical composition. Aims: The goal of the present investigation is the interpretation of recent JWST data of the low main sequence of 47 Tuc, in order to explore the stellar to sub-stellar transition, to derive the mass distribution of the individual sources and to disentangle stars from different populations. Methods: Stellar evolution modelling of low-mass stars of metallicity [Fe/H]=-0.78 and oxygen content [O/Fe]=+0.4 and [O/Fe]=0 is used to simulate the evolution of the first and the second generation of the cluster. The comparison between the calculated sequences with the data points is used to characterize the individual objects, to split the different stellar components and to infer the current mass function of the cluster. Results: The first generation of 47 Tuc harbours 45 % of the overall population of the cluster, the remaining 55 % making up the second generation. The transition from the stellar to the sub-stellar domain is found at $0.074 M_{\odot}$ and $0.07 M_{\odot}$ for the first and second generations, respectively. The mass function of both the stellar generations are consistent with a Kroupa-like profile down to $0.22 M_\odot$.
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All authors C. Ventura, M. Tailo, P. Ventura, F. D'Antona, A. P. Milone, A. F. Marino, C. Fiumi

Cosmology and Nongalactic Astrophysics · Cross-listed from hep-th

Extending Weinberg's EFT: effective scalar-tensor theories up to sixth order

Eugeny Babichev, Sukŗti Bansal, Maria Mylova et al. (+1 more)

We present a systematic construction of the six-derivative effective scalar-tensor theories, extending the four-derivative framework previously developed by Steven Weinberg. The on-shell effective field theory comprises five parity-even and three parity-odd independent six-derivative scalar-tensor interactions, representing all inequivalent deformations consistent with general covariance. We further confirm this operator counting through an independent analysis using the scattering amplitude formalism in four-dimensional flat spacetime. The six-derivative Lagrangian constructed here provides the next-to-leading-order extension of scalar-tensor gravity, furnishing a robust framework for exploring quantum or stringy corrections, parity-violating interactions, and strong-curvature effects in cosmology, black hole physics and gravitational wave observations.
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All authors Eugeny Babichev, Sukŗti Bansal, Maria Mylova, Antonio Padilla

Astrophysics of Galaxies

The excess of molecular hydrogen in chemical networks without oxygen

Sylvia Ploeckinger

We report the presence of a systematic excess in the molecular hydrogen fraction ($f_{\mathrm{H2}} = 2 \, n_{\mathrm{H2}}/n_{\mathrm{H}}$) in studies that use a reduced chemistry network to calculate $f_{\mathrm{H2}}$ of gas with a non-zero metal mass fraction. This is common practice in simulations of galaxy formation in which following the non-equilibrium abundances of additional elements is computationally expensive. We define the $\mathrm{H}_2$ excess as the shift in density of the \ion{H}{I}-$\mathrm{H}_2$ transition in the reduced network compared to the full chemical network (30 elements). The strength of the $\mathrm{H}_2$ excess generally increases both with temperature and metallicity, is largely independent of the radiation field strength, and persists across a large range of assumed shielding column densities. For warm gas, with $T\approx1000~\mathrm{K}$, the HI-$\mathrm{H}_2$ transition is shifted by up to 1 dex to lower densities in primordial chemistry networks already for extremely low metallicities ($Z\geq 10^{-4}\,\mathrm{Z}_{\odot}$). We confirm our earlier findings that missing reactions with oxygen are largely responsible for this $\mathrm{H}_2$ excess. A reduced chemical network of hydrogen, helium, and oxygen recovers the molecular hydrogen fractions from a full network and we therefore recommend to include destruction of molecular hydrogen by oxygen in a minimal chemical network for accurate molecular hydrogen abundances.
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High Energy Astrophysical Phenomena

PSR J0537-6910: Exponential recoveries detected for 12 glitches

E. Zubieta, C. M. Espinoza, D. Antonopoulou et al. (+4 more)

Pulsar glitches are unresolved increments of the rotation rate that sometimes trigger an enhancement of the spin-down rate. On occasions, the augmented spin-down decays gradually in an exponential manner, particularly after the largest glitch events. The young pulsar PSR J0537-6910 exhibits the highest known glitching rate, with 60 events detected in nearly 18 years of monitoring. Despite most PSR J0537-6910 glitches being large, only one exponential recovery has been reported, following its first discovered glitch. This is puzzling, as pulsars of similar characteristics typically present significant exponential recoveries. We aim to determine whether this reflects an intrinsic difference in PSR J0537-6910 or a detectability issue, for example due to its high glitch frequency. The full dataset, including recent NICER observations, was systematically searched for exponential relaxations. Each glitch was tested for evidence of a recovery over a broad range of trial timescales. Promising candidates were investigated further by comparing recovery models with and without an exponential term using Bayesian evidence. We discovered six new glitches, bringing the total to 66. Our criteria strongly indicates the presence of 11 previously undetected exponential recoveries. We presente updated glitch and timing solutions. Exponential recoveries are detected only for the largest glitches, though not all of them. The inferred timescales range from 4 to 37 d, with the decaying frequency increment generally below $1\%$ of the total. We find that $\ddot\nu$ can remain stable across several glitches, with persistent changes associated with only some events. In particular, it tends to be lowest after glitches with exponential recoveries, yielding inter-glitch braking indices between 6 and 9. Following glitches without recoveries, $\ddot\nu$ is higher, leading to braking indices between 10 and 35.
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All authors E. Zubieta, C. M. Espinoza, D. Antonopoulou, W. C. G. Ho, L. Kuiper, F. García, S. del Palacio

Solar and Stellar Astrophysics

Magnetic field generation in mergers of massive main-sequence stars

Sebastian T. Ohlmann, Fabian R. N. Schneider, Friedrich K. Roepke et al. (+3 more)

Magnetic fields are found in many astrophysical objects, ranging from galaxy clusters to the interstellar medium of galaxies and neutron stars. Strong surface magnetic fields are also observed in about 7% of OBA-type stars, and stellar mergers are the likely origin of at least some of them. We investigated magnetic-field amplification during the merger of a 9 and an 8 $M_\odot$ main-sequence star using 3D magnetohydrodynamic simulations from our previous work. We focused on the magnetic-field amplification mechanisms, field geometry, and the structure and properties of the resulting merger, in particular its rotational configuration. The merger produces a star-torus structure in which the core of the initially less massive star is surrounded by material from the primary. Initially, turbulent motions driven by Kelvin-Helmholtz and magneto-rotational instabilities generate small-scale magnetic fields. Subsequently, large-scale ordered azimuthal flows drive a larger-scale dynamo that amplifies and redistributes the magnetic energy to larger spatial scales, producing a remnant threaded by a strong large-scale magnetic field. The final magnetic configuration consists of intertwined poloidal and toroidal components, with a residual small-scale structure that resembles previously identified stable magnetic field equilibria. The amplification process is largely insensitive to the initial binary separation, numerical resolution, and seed magnetic-field strength. The central regions of the merger remnant rapidly approach solid-body rotation, transitioning to a Keplerian-like profile within the surrounding torus. Our results support stellar mergers as a viable pathway for the formation of strongly magnetic massive stars and potentially highly magnetized compact remnants, such as magnetic white dwarfs and magnetars.
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All authors Sebastian T. Ohlmann, Fabian R. N. Schneider, Friedrich K. Roepke, Ruediger Pakmor, Philipp Podsiadlowski, Volker Springel

Solar and Stellar Astrophysics

Defects and Inconsistencies in Solar Flare Data Sources: Implications for Machine Learning Forecasting

Ke Hu, Kevin Jin, Victor Verma et al. (+5 more)

Machine learning models for forecasting solar flares have been trained and evaluated using a variety of data sources, including Space Weather Prediction Center (SWPC) operational and science-quality data. Typically, data from these sources is minimally processed before being used to train and validate a forecasting model. However, predictive performance can be affected if defects and inconsistencies between these data sources are ignored. For a set of commonly used data sources, along with the software that queries and outputs processed data, we identify their defects and inconsistencies, quantify their extent, and show how they can affect predictions from data-driven machine-learning forecasting models. We also outline procedures for fixing these issues or at least mitigating their impacts. Finally, based on thorough comparisons of the effects of data sources on the trained forecasting model's predictive skill scores, we offer recommendations for using different data products in operational forecasting.
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All authors Ke Hu, Kevin Jin, Victor Verma, Weihao Liu, Ward Manchester IV, Lulu Zhao, Tamas Gombosi, Yang Chen

Astrophysics of Galaxies

Prospects for Measuring Black Hole Masses using TDEs with the Vera C. Rubin Observatory

K. Decker French, Brenna Mockler, Nicholas Earl et al. (+1 more)

Tidal Disruption Events (TDEs) provide an opportunity to study supermassive black holes that are otherwise quiescent. The Vera C. Rubin Legacy Survey of Space and Time will be capable of discovering thousands of TDEs each year, allowing for a dramatic increase in the number of discovered TDEs. The optical light curves from TDEs can be used to model the physical parameters of the black hole and disrupted star, but the sampling and photometric uncertainty of the real data will couple with model degeneracies to limit our ability to recover these parameters. In this work, we aim to model the impact of the Rubin survey strategy on simulated TDE light curves to quantify the typical errors in the recovered parameters. Black hole masses $5.5< \log M_{\rm BH}/M_\odot < 8.2$ can be recovered with typical errors of 0.26 dex, with early coverage removing large outliers. Recovery of the mass of the disrupted star is difficult, limited by the degeneracy with the accretion efficiency. Only 57% of the cases have accurate recovery of whether the events are full or partial, so we caution the use this method to assess whether TDEs are partially or fully disrupted systems. Black hole mass measurements obtained from Rubin observations of TDEs will provide powerful constraints on the black hole mass function, black hole – galaxy co-evolution, and the population of black hole spins, though continued work to understand the origin of TDE observables and how the TDE rate varies among galaxies will be necessarily to fully utilize the upcoming rich data set from Rubin.
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All authors K. Decker French, Brenna Mockler, Nicholas Earl, Tanner Murphey

High Energy Astrophysical Phenomena

Three-dimensional numerical simulations of neutron star cores in the two-fluid MHD approximation: simple configurations

Andrei Igoshev, Nicolás A. Moraga, Andreas Reisenegger et al. (+2 more)

Magnetic field evolution in neutron star cores is not fully understood. We describe the field evolution both for one barotropic fluid as well as two collisionally coupled barotropic fluids with different density profiles using the anelastic approximation and the Navier-Stokes equations to simulate the evolution in three dimensions. In the one-fluid case, a single fluid describes the motion of the charged particles. In the two-fluid model, the neutral fluid is coupled to the electrically conductive fluid by collisions, the latter being dragged by the magnetic field. In this model, both fluids have distinct density profiles. This forces them to move at slightly different velocities, resulting in a relative motion between the two barotropic fluids – ambipolar diffusion. We develop a code based on Dedalus and study the evolution of simple poloidal dipolar and toroidal magnetic fields. Previous 2D studies found that poloidal magnetic fields evolve towards a stable Grad-Shafranov equilibrium. In our 3D simulations we find an instability of the two-fluid system similar to the one in the barotropic fluid system. After the instability saturates, a highly non-linear Lorentz force introduces small-scale fluid motion that leads to turbulence, development of a cascade and significant, non-axially symmetric changes in the magnetic field configuration. Fluid viscosity plays an essential role in regularizing the small-scale fluid motion, providing an energy drain.
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All authors Andrei Igoshev, Nicolás A. Moraga, Andreas Reisenegger, Calum S. Skene, Rainer Hollerbach

Solar and Stellar Astrophysics

Citizen CATE 2024: Extending Totality During the 8 April 2024 Total Solar Eclipse with a Distributed Network of Community Participants

Sarah A. Kovac, Amir Caspi, Daniel B. Seaton et al. (+240 more)

The Citizen CATE 2024 next-generation experiment placed 43 identical telescope and camera setups along the path of totality during the total solar eclipse (TSE) on 8 April 2024 to capture a 60-minute movie of the inner and middle solar corona in polarized visible light. The 2024 TSE path covered a large geographic swath of North America and we recruited and trained 36 teams of community participants ("citizen scientists") representative of the various communities along the path of totality. Afterwards, these teams retained the equipment in their communities for ongoing education and public engagement activities. Participants ranged from students (K12, undergraduate, and graduate), educators, and adult learners to amateur and professional astronomers. In addition to equipment for their communities, CATE 2024 teams received hands-on telescope training, educational and learning materials, and instruction on data analysis techniques. CATE 2024 used high-cadence, high-dynamic-range (HDR) polarimetric observations of the solar corona to characterize the physical processes that shape its heating, structure, and evolution at scales and sensitivities that cannot be studied outside of a TSE. Conventional eclipse observations do not span sufficient time to capture changing coronal topology, but the extended observation from CATE 2024 does. Analysis of the fully calibrated dataset will provide deeper insight and understanding into these critical physical processes. We present an overview of the CATE 2024 project, including how we engaged local communities along the path of totality, and the first look at CATE 2024 data products from the 2024 TSE.
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All authors Sarah A. Kovac, Amir Caspi, Daniel B. Seaton, Paul Bryans, Joan R. Burkepile, Sarah J. Davis, Craig E. DeForest, David Elmore, Sanjay Gosain, Rebecca Haacker, Marcus Hughes, Jason Jackiewicz, Viliam Klein, Derek Lamb, Valentin Martinez Pillet, Evy McUmber, Ritesh Patel, Kevin Reardon, Willow Reed, Anna Tosolini, Andrei E. Ursache, John K. Williams, Padma A. Yanamandra-Fisher, Daniel W. Zietlow, John Carini, Charles H. Gardner, Shawn Laatsch, Patricia H. Reiff, Nikita Saini, Rachael L. Weir, Kira F. Baasch, Jacquelyn Bellefontaine, Timothy D. Collins, Ryan J. Ferko, Leticia Ferrer, Margaret Hill, Jonathan M. Kessler, Jeremy A. Lusk, Jennifer Miller-Ray, Catarino Morales III, Brian W. Murphy, Kayla L. Olson, Mark J. Percy, Gwen Perry, Andrea A. Rivera, Aarran W. Shaw, Erik Stinnett, Eden L. Thompson, Hazel S. Wilkins, Yue Zhang, Angel Allison, John J. Alves, Angelica A. Alvis, Lucinda J. Alvis, Alvin J.G. Angeles, Aalasia Batchelor, Robert Benedict, Amelia Bettati, Abbie Bevill, Katherine Bibee Wolfson, Christina Raye Bingham, Bradley A. Bolton, Iris P. Borunda, Mario F. Borunda, Adam Bowen, Daniel L. Brookshier, MerRick Brown, Fred Bruenjes, Lisa Bunselmeier, Brian E. Burke, Bo Chen, Chi-Jui Chen, Zhean Chen, Marcia Chenevey Long, Nathaniel D. Cook, Tommy Copeland, Adrian J. Corter, Lawson L. Corter, Michael J. Corter, Theresa N. Costilow, Lori E. Cypert, Derrion Crouch-Bond, Beata Csatho, Clayton C. Cundiff, Stella S. Cundiff, Darrell DeMotta, Judy Dickey, Hannah L. Dirlam, Nathan Dodson, Donovan Driver, Jennifer Dudley-Winter, Justin Dulyanunt, Jordan R. Duncan, Scarlett C. Dyer, Lizabeth D. Eason, Timothy E. Eason, Jerry L. Edwards, Jaylynn N. Eisenhour, Ogheneovo N. Erho, Elijah J. Fleming, Andrew J. Fritsch III, Stephanie D. Frosch, Sahir Gagan, Joshua Gamble, Caitlyn L. Geisheimer, Ashleyahna George, Treva D. Gough, Jo Lin Gowing, Robert Greeson, Julie D. Griffin, Justin L. Grover, Simon L. Grover, Annie Hadley, Austin S. Hailey, Katrina B. Halasa, Jacob Harrison, Rachael Heltz Herman, Melissa Hentnik, Robert Hentnik, Mark Herman, Brenda G. Henderson, David T. Henderson, J. Michael Henthorn II, Thomas Hogue, Billy J. House, Toni Ray Howe, Brianna N. Isola, Mark A. Iwen, Jordyn Johnson, Richard O. Johnson III, Sophia P. Jones, Hanieh Karimi, Katy R. Kiser, Michael K. Koomson Jr., Morgan M. Koss, Ryan P. Kovacs, Carol A. Kovalak Martin, Kassidy Lange, Kyle Lawrence Leathers, Michael H. Lee, Kevin W. Lehman, Garret R. Leopold, Hsiao-Chun Lin, Heather Liptak, Logan Liptak, Michael A. Liptak, Alonso Lopez, Evan L. Lopez, Don Loving, April Luehmann, Kristen M. Lusk, Tia L. MacDonald, Ian A. Mannings, Priscilla Marin, Christopher J. Martin, Jamie Martin, Alejandra Olivia Martinez, Terah L. Martinez, Elizabeth S. Mays, Seth McGowan, Edward M. McHenry III, Kaz Meszaros, Tyler J. Metivier, Quinn W. Miller, Adam V. Miranda, Carlos Miranda, Pranvera Miranda, David M. W. Mitchell, Lydia N. Montgomery, Christopher P. Morse, Lillie B. Moore, Ira S. Morse, Raman Mukundan, Patrick T. Murphy, Nicarao J. Narvaez, Ahmed Nasreldin, Thomas Neel, Travis A. Nelson, Ellianna Nestlerode, Adam Z. Neuville, Brian A. Neuville, Allison Newberg, Jeremy L. Nicholson, Makenna F. Nickens, Sining Niu, Jedidiah O'Brien, Luis A. Otero, Jacob A. Ott, Joel A. Ott, Justin M. Ott, Michael E. Ott, Shekhar Pant, Ivan Parmuzin, Eric J. Parr, Sagar P. Paudel, Courtney M. Payne, Hayden B. Phillips, Elizabeth R. Prinkey, Kwesi A. Quagraine, Wesley J. Reddish, Azariah Rhodes, Stephen Kyle Rimler, Carlyn S. Rocazella, Tiska E. Rodgers, Devalyn Rogers, Oren R. Ross, Benjamin D. Roth, Melissa Rummel, John F. Rusho, Michael W. Sampson, Sophia Saucerman, James Scoville, Martin Wayne Seifert, Michael H. Seile Sr., Thomas G. Skirko, Asad Shahab, David C. Smith, Emily R. Snode-Brenneman, Cassandra Spaulding, Neha Srivastava, Amy L. Strecker, Aidan Sweets, Morghan Taylor, Deborah S. Teuscher, Owen Totten, Stephen Totten, Stephanie Totten, Andrew Totten, Corina R. Ursache, Susan V. Benedict, Yolanda Vasquez, R. Anthony Vincent, Alan Webb, Walter Webb, Roderick M. Weinschenk, Sedrick Weinschenk, Cash A. Wendel, Elisabeth Wheeler, Bethany A. Whitehouse, Gabriel J. Whitehouse, David A. Wiesner, Philip J. Williams, John A. Zakelj

Instrumentation and Methods for Astrophysics

diffhydro: Inverse Multiphysics Modeling and Embedded Machine Learning in Astrophysical Flows

Benjamin Horowitz, Zarija Lukić, Kentaro Nagamine et al. (+1 more)

We present the extension of the differentiable hydrodynamics code, diffhydro, enabling scalable PDE-constrained inference and integrated hybrid physics-ML models for a wide range of astrophysical applications. New physics additions include radiative heating/cooling, OU-driven turbulence, and self-gravity via multigrid Poisson. We demonstrate good agreement with the Athena++ code on standard validation tests such as Sedov-Taylor, Kelvin-Helmholtz, and driven/decaying turbulence. We further introduce a solver-in-the-loop neural corrector that reduces coarse-grid errors during time integration while preserving stability. The addition of custom adjoints facilitates efficient end-to-end gradients and multi-device scaling. We present simulations up to 1024^3 elements, run on distributed GPU systems, and we show gradient-based reconstructions of complex initial conditions in turbulent, self-gravitating, radiatively cooling flows. The code is written in JAX, and the solver's modular finite-volume components are compiled by XLA into fused accelerator kernels, delivering high-throughput forward runs and tractable differentiation through long integrations.
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All authors Benjamin Horowitz, Zarija Lukić, Kentaro Nagamine, Yuri Oku

Instrumentation and Methods for Astrophysics

Multiband neural network classification of ZTF light curves as LSST proxies

Tamás Szklenár, Attila Bódi and Róbert Szabó

In this project we use data obtained by Zwicky Transient Facility to develop and test a neural-network-based, multiband classification algorithm to classify periodic variable stars (i.e. pulsating variable stars and eclipsing binaries). The aim is to utilize the algorithm on LSST data once they become available. Phase-folded light curve images and period information were used from five different variable star types: Classical and Type II Cepheids, {\delta} Scuti stars, eclipsing binaries, and RR Lyrae stars. The data is taken from the 17th data release of ZTF, from which we used two passbands, g and r in this project. The periods were calculated from the raw data and this information was used as an additional numerical input in the neural network. For the training and testing process a supervised machine learning method was created, the neural network contains Convolutional Neural Networks concatenated with Fully Connected Layers. During the training-validation process the training accuracy reached 99% and the validation accuracy peaked at 95.6%. At the test classification phase three variable star types out of the 5 classes were classified with around 99% of accuracy, the other two also had very high accuracy, 89.6% and 93.6%.
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Solar and Stellar Astrophysics

The Maximum Particle Energy Gain During Magnetic Reconnection

Zhiyu Yin, Harry Arnold, James F Drake et al. (+1 more)

The factors that control the maximum energy attained by protons and electrons during magnetic reconnection are investigated analytically and using large-scale simulations with the kglobal model. Previous work revealed that a strong ambient guide field strongly impacts particle energy gain during reconnection, suppressing energy gain from Fermi reflection by increasing the radius of curvature of reconnected field lines. However, previous simulations have also shown that the maximum energy gain increases with the system size. The physical basis for this result has not been explored. We perform simulations that vary the effective system size over a large range to isolate the processes determining the maximum energy gain. The maximum energy $W_{max}$ is regulated by the number of magnetic-island mergers that occur, as multiple flux ropes that form at early time repeatedly merge until the largest approaches the system scale. Fermi reflection in these repeated mergers dominates particle energy gain. The number of mergers is linked to the effective system size – larger systems produce a larger number of flux ropes and more mergers. That $W_{max}$ is linked to the number of flux rope mergers has implications for understanding why particle-in-cell simulations only produce powerlaw distributions of energetic particles with a limited range in energy.
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All authors Zhiyu Yin, Harry Arnold, James F Drake, Marc Swisdak

Solar and Stellar Astrophysics

Statistical properties of spicules in MURaM-ChE

Sanghita Chandra, Robert Cameron, Damien Przybylski et al. (+1 more)

Numerical simulations of the solar chromosphere have progressed towards reproducing spicules, which are transient features observed at the solar limb using spectral lines such as H$\alpha$, Ca II H&K, or Mg II h&k. Two types of spicules, referred to as types I and II, have been identified in observations and studied in previous numerical works. The statistics of type II spicules in 3D numerical simulations have not yet been studied. We aim to compare the statistics of properties such as lengths, lifetimes, widths, heights, inclinations, and maximum velocities of self-consistently formed spicules in a MURaM-ChE simulation with observations. We employ a H$\alpha$ proxy to identify fine-scale structures at the solar limb resembling spicules in a simulation of an enhanced network region. We track the evolution of 58 such features found in a 21-minute time sequence, and compare their dynamical and morphological properties with those derived from quiet-Sun observations using the Solar Optical Telescope (SOT) onboard the Hinode mission in the Ca II H spectral line. Previous studies have shown that spicules show very similar properties in Ca II H and H$\alpha$. The spicule-like structures found in the simulation have statistical properties which are broadly consistent with those observed with Hinode/SOT. In particular, we find evidence for the self-consistent formation of both type I and type II spicules within the simulation, even in the absence of ambipolar diffusion. We also investigate the properties of rapid blueshifted and redshifted excursions (RBEs and RREs) in the simulation in relation to the spicules.
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All authors Sanghita Chandra, Robert Cameron, Damien Przybylski, Sami K. Solanki

Astrophysics of Galaxies

The PAU Survey: Uncovering the connection between intrinsic and observed galaxy properties using symbolic regression

Adarsh Kumar, Carlton M. Baugh, Suttikoon Koonkor et al. (+12 more)

Estimating stellar masses for billions of galaxies in upcoming surveys requires methods that are both accurate and computationally efficient. We present a new approach using symbolic regression trained on a simulation to derive simple, explicit mathematical expressions that estimate galaxy stellar masses from basic observables: photometry and redshift. Using a mock catalogue from the GALFORM semi-analytical model that reproduces the Physics of the Accelerating Universe Survey (PAUS), we show that a linear combination of just four observables – minimally processed $u$- and $i$- band magnitudes, observed $(g-r)$ colour, and redshift – can recover stellar masses with accuracy comparable to traditional spectral energy distribution (SED) fitting, but with negligible computational cost. Our expressions can be evaluated instantaneously for millions of galaxies, making them ideal for next-generation surveys like LSST and Euclid. When observational errors are included, symbolic regression achieves a similar accuracy to deep neural networks while maintaining transparency. Validation against CIGALE SED fitting on PAUS data shows agreement within 0.13 dex for galaxies with $M_{*} > 10^8 M_{\odot}$. We demonstrate that the stellar mass function can be recovered at $z < 0.5$, though with distortions at the extremes: the high-mass end is overestimated by a factor of $\sim 3$ at $10^{11.5} h^{-1} M_{\odot}$ due to scatter. Our approach offers a fast, transparent alternative to traditional methods without sacrificing accuracy for the bulk of the galaxy population.
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All authors Adarsh Kumar, Carlton M. Baugh, Suttikoon Koonkor, Giorgio Manzoni, Sukanta Panda, D. Navarro Girones, R. Casas, J. Carretero, F. Castander, J. De Vicente, J. Garcia Bellido, E. Gaztanaga, R. Miquel, P. Renard, P. Tallada Crespi

Astrophysics of Galaxies

ALMA view on the nature of the compact VLA continuum sources in the massive young stellar object G25.65+1.05

N. N. Shakhvorostova, A. M. Sobolev, D. A. Ladeyshchikov et al. (+3 more)

This paper presents high-resolution ALMA observations of the massive young stellar object G25.65+1.05, which is known to host water maser super flares. To investigate the nature of compact continuum sources that have been previously identified in this region, we analyzed 1.3 mm dust continuum and molecular line emission. The central millimeter peak MM1 coincides with the centimeter source VLA 2, has a complex molecular spectrum, and is identified as a hot molecular core. Molecular emission of SiO and CH3CN in the vicinity of MM1 reveals kinematics consistent with wide-angle outflow structures and a possible rotating disk in the source. VLA sources 1A, 1B, and 3 are lacking compact millimeter counterparts and trace shocked regions where the outflow interacts with the surrounding material. In particular, VLA 1A, the site of H2O maser super flares, is interpreted as a shock interface that exhibits developed turbulent movements seen in the SiO molecular line. The observed turbulence creates conditions required for H2O maser action, directly linking the nature of VLA 1A to the origin of the H2O maser super flares.
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All authors N. N. Shakhvorostova, A. M. Sobolev, D. A. Ladeyshchikov, S. Y. Parfenov, A. A. Shagabutdinov, S.-Y. Liu

Astrophysics of Galaxies

Super-resolving Herschel - a deep learning based deconvolution and denoising technique

Dennis Koopmans, Lingyu Wang, Berta Margalef-Bentabol et al. (+9 more)

Dusty star-forming galaxies (DSFGs) dominate the far-infrared and sub-millimetre number counts, but single-dish surveys suffer from poor angular resolution, complicating mult-wavelength counterpart identification. Prior-driven deblending techniques require extensive fine-tuning and struggle to process large fields. This work aims to develop a fast, reliable deep-learning based deconvolution and denoising super-resolution (SR) technique. We employ a transformer neural network to improve the resolution of Herschel/SPIRE 500 $\mu$m observations by a factor 4.5, using Spitzer/MIPS 24$\mu$m and Herschel/SPIRE 250, 350, 500$\mu$m images. Trained on SIDES and SHARK simulations, we injected instrumental noise into the input simulated images, while keeping the target images noise-free to enhance de-noising capabilities of our method. We evaluated the performance on simulated test sets and real JCMT/SCUBA-2 450 $\mu$m observations in the COSMOS field which have superior resolution compared to Herschel. Our SR method achieves an inference time of $1s/deg^2$ on consumer GPUs, much faster than traditional deblending techniques. Using the simulation test sets, we show that fluxes of the extracted sources from the super-resolved image are accurate to within 5% for sources with an intrinsic flux $\gtrsim$ 8 mJy, which is a substantial improvement compared to blind extraction on the native images. Astrometric error is low ($\lesssim$ 1" vs 12" pixel scale). Reliability is $\gtrsim$ 90% for sources $>$3 mJy and $>$90% of sources with intrinsic fluxes $\gtrsim5$ mJy are recovered. Applied to real 500 $\mu$m observations, fluxes of the extracted sources from the super-resolved map agree well with SCUBA-2 measured fluxes for sources $\geq$10 mJy. Our technique enables SR over hundreds of $deg^2$ without the need for fine-tuning, facilitating statistical analysis of DSFGs.
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All authors Dennis Koopmans, Lingyu Wang, Berta Margalef-Bentabol, Antonio La Marca, Matthieu Bethermin, Laura Bisigello, Zhen-Kai Gao, Claudia del P. Lagos, Lynge Lauritsen, Stephen Serjeant, F.F.S. van der Tak, Wei-Hao Wang

Astrophysics of Galaxies

Standardizing reverberation-mapped H$\beta$ active galactic nuclei using time-averaged radius$-$luminosity relations with 5100\,Å\,, broad H$\beta$, and narrow \OIII\ luminosities

Shulei Cao, Amit Kumar Mandal, Michal Zajaček et al. (+1 more)

Active galactic nuclei (AGN) have been studied as alternate probes in cosmology due to their large and stable luminosities and broad redshift range. Previously it was shown that higher-redshift AGN that were reverberation-mapped (RM) using broad Mg\,ii and C\,iv lines are standardizable and yield weak cosmological constraints that are consistent with those from better-established probes. In contrast, lower-redshift AGN that were reverberation-mapped using the broad H$\beta$ line exhibited tensions with the standard cosmological model, in particular they preferred currently decelerating cosmological expansion. Here we study the standardizability of a homogeneous RM H$\beta$ sample of $\sim 100$ AGN (over redshifts $0.00308 \leq z \leq 0.8429$), whose H$\beta$ time delays and three luminosity tracers (at 5100\,Å\,, broad H$\beta$, and narrow [O\,iii]) are averaged over several epochs. We find that this averaged sample is standardizable using three $R-L$ relations. While for luminosities corresponding to 5100\,Å\, and the broad H$\beta$ line the cosmological constraints prefer currently decelerating cosmological expansion, the cosmological parameters for the narrow [O\,iii] luminosity are more consistent with those from better-established probes and they are in agreement with currently accelerating cosmological expansion. This demonstrates for the first time that narrow-line region [O\,iii] can be utilized for AGN standardization and cosmological constraints. Selecting proper photoionizing flux proxies for the broad-line region is thus crucial in studies of RM AGN standardizability.
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All authors Shulei Cao, Amit Kumar Mandal, Michal Zajaček, Bharat Ratra

Solar and Stellar Astrophysics

Evidence for in situ particle energization during the May-2024 event based on ASPEX instrument on board Aditya-L1

Shivam Parashar, Dibyendu Chakrabarty, Prashant Kumar et al. (+26 more)

The interaction between interplanetary Coronal Mass Ejection (ICME) structures can alter the geo-effectiveness of the ICME events in myriad ways. Many aspects of these interaction processes are not well-understood till date. Using the energy spectra measured in two mutually orthogonal top hat analyzers (THA 1 and 2), which are part of the Solar Wind Ion Spectrometer (SWIS) subsystem of the Aditya Solar Wind Particle EXperiment (ASPEX) on board India's Aditya L1 mission, we gain insights into intricate features of ICME ICME interactions during May 2024 solar event. We report here an unprecedented two-orthogonal-plane perspective of ICME ICME interactions for the first time from the L1 point. The investigation reveals a special interaction region formed by the propagation of the forward shock driven by complex ejecta in the preceding ICME. The interaction causes the formation of a downstream region spanning over 13 hours, which propagates in the interplanetary medium. The observations reveal that this region serves as a site for proton and alpha particle energization, and the particles within this region get distributed from one plane to the other. The presence of forward shock and particle energization is confirmed by the energetic particle flux measurements by the SupraThermal and Energetic Particle Spectrometer (STEPS) of ASPEX. These observations provide an unprecedented perspective on how solar wind ions become energized and distributed in an ICME-ICME interaction region.
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All authors Shivam Parashar, Dibyendu Chakrabarty, Prashant Kumar, Abhishek Kumar, Bhas Bapat, Aveek Sarkar, P. Janardhan, Anil Bhardwaj, Santosh V. Vadawale, Manan S. Shah, Hiteshkumar L. Adalja, Arpit R. Patel, Pranav R. Adhyaru, M. Shanmugam, Swarop B. Banerjee, K. P. Subramanian, Tinkal Ladia, Jacob Sebastian, Bijoy Dalal, Aakash Gupta, Shiv Kumar Goyal, Neeraj Kumar Tiwari, Aaditya Sarda, Sushil Kumar, Nishant Singh, Deepak Kumar Painkra, Piyush Sharma, Abhishek J. Verma, M. B. Dadhania

Astrophysics of Galaxies

HALO I: Photometric continuum reverberation mapping of Fairall 9

Amit Kumar Mandal, Francisco Pozo Nuñez, Vikram Kumar Jaiswal et al. (+23 more)

We investigate the origin of inter-band continuum time delays in active galactic nuclei (AGNs) to study the structure and properties of their accretion disks. We aim to measure the inter-band continuum time delays through photometric monitoring of Seyfert galaxy Fairall 9 to construct the lag-spectrum. Additionally, we explain the observed features in the Fairall 9 lag-spectrum and discuss the potential drivers behind them, based on our newly collected data from the Obserwatorium Cerro Murphy (OCM) telescope. We initiated a long-term, continuous AGN photometric monitoring program in 2024, titled 'Hubble constant constraints through AGN Light curve Observations' (HALO) using intermediate and broad band filters. Here, we present the first results from HALO, focusing on photometric light curves and continuum time-delay measurements for Fairall 9. To complement these observations and extend the wavelength coverage of the lag-spectrum, we also reanalyzed archival Swift light curves and spectroscopic data available in the literature. Using HALO and Swift light curves, we measured inter-band continuum delays to construct the lag-spectrum of Fairall 9. Excess lags appear in the $u$ and $U$ bands (Balmer continuum contamination) and in the $I$ band (Paschen jump/dust emission from the torus). Overall, the lag-spectrum deviates significantly from standard disk model predictions. We find that inter-band delays deviate from the power-law, $\tau_{\lambda} \propto \lambda^{\beta}$ due to BLR scattering, reprocessing, and dust contributions at longer wavelengths. Power-law fits are therefore not well suited for characterizing the nature of the time delays.
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All authors Amit Kumar Mandal, Francisco Pozo Nuñez, Vikram Kumar Jaiswal, Mohammad Hassan Naddaf, Bożena Czerny, Swayamtrupta Panda, Paulina Karczmarek, Grzegorz Pietrzyński, Shivangi Pandey, B. M. Peterson, Michal Zajaček, Michal Dovčiak, Vladimir Karas, Weronika Narloch, Mirosław Kicia, Marek Górski, Mikołaj Kałuszyński, Gergely Hajdu, Piotr Wielgórski, Bartłomiej Zgirski, Cezary Gałan, Wojciech Pych, Radosław Smolec, Karolina Bąkowska, Wolfgang Gieren, Pierre Kervella

Astrophysics of Galaxies

Tidally Perturbed, Rotating Stellar Systems: Asynchronous Equilibria

Lucy A. Z. Arditi and Anna Lisa Varri

We present a new three-parameter family of self-consistent equilibrium models for quasi-relaxed stellar systems that are subject to the combined action of external tides and rigid internal rotation. These models provide an idealised description of globular clusters that rotate asynchronously with respect to their orbital motion around a host galaxy. Model construction proceeds by extension of the truncated King models, using a newly defined asynchronicity parameter to couple the tidal and rotational perturbations. The method of matched asymptotic expansion is used to derive a global solution to the free boundary problem posed by the corresponding set of Poisson-Laplace equations. We explore the relevant parameter space and outline the intrinsic properties of the resulting models, both structural and kinematic. Their triaxial configuration, characterised by extension in the direction of the galactic centre and flattening toward the orbital plane, is found to depart further from spherical symmetry for larger values of the asynchronicity parameter. We hope that these simplified analytical models serve as useful tools for investigating the interplay of tidal and rotational effects, providing an equilibrium description that complements, and may serve as a basis for, more realistic numerical simulations.
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Solar and Stellar Astrophysics

Challenging historical novae: AT Cnc (1645), Te-11 (483), and M22 (BC 48) revisited

D.L. Neuhäuser, R. Neuhäuser, V. Hambaryan et al. (+2 more)

Connections between novae with shells and historical observations are crucial for astrophysical understanding of long-term evolution of shells and cataclysmic variables. Three of five previously considered links are revisited here: extended features in M22 in BC48, Te-11 in 483, and AT Cnc in 1645. We aim to develop a procedure to check whether these links are credible. Literal translations of the Chinese texts, historically based arguments, and close readings are combined with astrophysics, (peak brightness, decay time estimate, shell age expansion model calculation, etc.). (a) Nandou's second star, near which the BC48 `guest star' was reported, is identified as tau Sgr, not lambda Sgr, far from the M22 location. A nova in M22 would peak at only m=6.4 \pm 1.4 mag, and thus a description as a `blue-white' `melon' does not fit; it was likely a comet. (b) The imprecise position (`Shen['s] east') of the `guest star' in 483, its extended (dipper-like) radiance, and the context speak for a bolide. Considering the new (larger) Gaia distance and small extinction towards Te-11 (outside a cloud), its bi-polar morphology and current expansion velocity point to a planetary nebula; as a nova, the shell expansion age is 1100-2000 yr from detailed supersonic expansion calculations. (c) Most certainly, Mars was meant when the source for 1645 reported `a large star entered Yugui'; the verb implies motion. AT Cnc lies neither in Yugui's asterism box nor in the eponymous lunar mansion range. The fluid drag expansion age of AT Cancri's ejecta is 128-631 yr. All three exact ages are unsubstantiated. True novae or nova shells can be connected to historical records only if the position and object type are plausible. Duration, brightness (light curve), and color (evolution) should fit and could provide more astrophysical insight ...
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All authors D.L. Neuhäuser, R. Neuhäuser, V. Hambaryan, J. Chapman, M. Della Valle

High Energy Astrophysical Phenomena

Constraints on dark matter annihilation from a nearby subhalo candidate

Ben-Yang Zhu, Yun-Feng Liang and Xiaoyuan Huang

A recent analysis of pulsar timing data has reported evidence for a massive ($\sim 6 \times 10^7 M_{\odot}$) dark matter subhalo located only $\sim 0.8$ kpc from Earth. This candidate implies an exceptionally large $J$-factor of $\sim 10^{23}\,{\rm GeV^2\,cm^{-5}}$, exceeding that of known classical dwarf spheroidal galaxies by orders of magnitude and rivaling the Galactic Center. In this work, we utilize more than 17 years of $\textit{Fermi}$-LAT data to search for gamma-ray emission from this subhalo. We identify a tentative excess in the region with ambiguous origin. Adopting a conservative strategy, we retain this excess without modeling additional astrophysical components, treating it instead as unmodeled background to derive upper limits on the dark matter annihilation cross-section for the $b\bar{b}$ and $\tau^+\tau^-$ channels. Despite this conservative treatment, the resulting limits remain stringent due to the exceptionally large $J$-factor. Subject to the dynamical confirmation of the subhalo, these constraints are potentially orders of magnitude stronger than those obtained from combined analyses of dwarf spheroidal galaxies and blind subhalo searches.
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Astrophysics of Galaxies

APOGEE physical properties of globular cluster tidal tails

André E. Piatti

A recent model prediction claimed that exists a correlation between the formation scenarios of globular clusters, i.e., whether they formed in situ, or in dark matter halos that were accreted into the Milky way, with some properties of their tidal tails, particularly, their widths ($w$), their dispersion in the z-component of the angular momentum ($\sigma$$_{\rm L_z}$ ), and in the line-of-sight ($\sigma$$_{\rm V_{LOS}}$) and tangential ($\sigma$$_{\rm V_{Tan}}$) velocities. I exploited the APOGEE DR17 data base and selected highly confident tidal tails members of 17 Milky Way globular clusters, for which the above four properties were computed for the first time. From all possible paired property combinations, I found that $\sigma$$_{\rm V_{LOS}}$ and $\sigma$$_{\rm V_{Tan}}$ resulted to be highly correlated, nearly to the identity relationship. This observation-based correlation resulted to be in an overall very good agreement with that arising from the aforementioned predictions. Additionally, when the four analyzed properties are linked to the accretion groups of the Milky way to which the globular clusters are meant to be associated, I found kinematically cold and hot tidal tails pertaining to globular clusters distributed in all the considered accretion groups. This outcome could be an evidence that globular clusters form in galaxies within a wide variety of dark matter halos, with different masses and profiles.
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Astrophysics of Galaxies

Non-detection of J1407b in ALMA Band 7 Observations

Pamela Klaassen, Matthew Kenworthy, Eric Mamajek et al. (+4 more)

We report on ALMA Band 7 continuum observations towards the star 1SWASP J140747.93-394542.6 taken in mid 2024. These observations were a follow-up of a previous detection of an emission source in the J1407 field of view at an unexpected position in 2017. Proper motion analysis indicated that if this were the object responsible for the 2007 eclipse of J1407, it would be detectable at a new position, but still within an ALMA field of view in 2024. Here we present the non-detection of emission in the ALMA field of view (to a 1{\sigma} upper limit of 17.5 {\mu}Jy),at both the 2017 position, and the position expected from proper motions. We place upper limits on a source at the proper motion corrected expected location in this 2024 data, and rule out the possibility of a dusty object being responsible for the 2007 eclipse
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All authors Pamela Klaassen, Matthew Kenworthy, Eric Mamajek, Nienke van der Marel, Michiel Min, Amaury Triaud, Antonion Hales

Cosmology and Nongalactic Astrophysics

Beyond general relativity: probing gravity with gravitational redshifts

Eleni Tsaprazi, Giorgio F. Lesci, Federico Marulli et al. (+7 more)

Despite the success of general relativity (GR), the unexplained nature of dark energy on cosmological scales leaves open the question of whether GR provides a complete description of gravity. This quest is further motivated by growing tensions among cosmological observations when interpreted within $\Lambda$CDM. Gravitational redshifts of cluster member galaxies probe cluster potentials on megaparsec scales directly, complementing conventional large-scale structure tests. Here, we investigate how redshift precision and survey design propagate into constraints on modified gravity using an end-to-end pipeline run on mock catalogues, focusing on mis-centring and spectroscopic completeness. We find that competitive measurements require wide-field spectroscopic cluster surveys explicitly designed to maximise the number of spectroscopically confirmed members per cluster, to enable high-purity stacking, and to control systematic effects.
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All authors Eleni Tsaprazi, Giorgio F. Lesci, Federico Marulli, Alan F. Heavens, Piero Rosati, Sofia Contarini, Enrico A. Maraboli, Pratika Dayal, Ofer Lahav, Lauro Moscardini

Astrophysics of Galaxies

Dust emission and extinction in the Orion OMC-3 cloud

M. Juvela and N. Ysard

Dust is an important tracer of the structure of interstellar clouds, as well as a central factor in the thermal balance and chemistry of the clouds. Our knowledge of the dust properties is nevertheless incomplete, especially regarding the dense star-forming clouds. The aim is to study dust evolution in the Orion Molecular Cloud 3 (OMC-3) and how uncertainty regarding dust properties affects estimates of the radiation field and the cloud mass. We constructed three-dimensional radiative transfer (RT) models to fit the far-infrared (FIR) observations of dust emission in the OMC-3 field and used near-infrared (NIR) extinction measurements as additional constraints. We examined fits to the dense star-forming filaments and to the surrounding cloud, including some tests with spatial dust property variations.The 160-250 $\mu$m observations of dust emission could be fitted moderately well with any of the dust models tested, but few models are consistent with the measured NIR extinction. The best match to observations is found with dust models such as the THEMIS model of large porous grains, with or without ice mantles, and with mean grain sizes up to ~ 0.3$\mu$m. The flattening of the NIR extinction curve excludes larger grain sizes, except possibly in the central ridge. Compared to models of lower column density clouds, the results were relatively insensitive to the line-of-sight (LOS) cloud size and the spectral shape of the heating radiation field. In addition, the effect of embedded stars remained very localised in OMC-3. The results suggest that the dust in the OMC-3 region is evolved with a grain of average size $a$=0.1-0.3 $\mu$m, potentially with ice mantles.
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