#galaxy-clusters — Public Fediverse posts

Weekly Update from the Open Journal of Astrophysics – 11/04/2026

With permission, I have time for yet another Saturday morning update of activity at the Open Journal of Astrophysics. Since the last update we have published a further five papers, bringing the number in Volume 9 (2026) to 76 and the total so far published by OJAp up to 524.

I will continue to include the posts made on our Mastodon account (on Fediscience) to encourage you to visit it. Mastodon is a really excellent service, and a more than adequate replacement for X/Twitter (which nobody should be using); these announcements also show the DOI for each paper.

The first paper to report this week is “Lagrangian versus Eulerian Methods for Toroidally-Magnetized Isothermal Disks” by Yashvardhan Tomar and Philip F. Hopkins (California Institute of Technology, USA). This study re-evaluates previous research on toroidally-magnetized disks, using two Lagrangian methods. The results suggest that sustained midplane toroidal fields in recent simulations are not a numerical artefact. It was published on Tuesday April 7th 2026 in the folder High-Energy Astrophysical Phenomena.

The overlay is here:

You can find the officially accepted version on arXiv here and the announcement on Fediverse here:

https://fediscience.org/@OJ_Astro/116362395042011770

The second paper for this week, published on Wednesday 8th Apil in the folder Instrumentation and Methods for Astrophysics, is “Teaching Astronomy with Large Language Models” by Yuan-Sen Ting and Teaghan O’Briain (Ohio State University, USA). The paper introduces AstroTutor, an AI-enhanced astronomy tutoring system, to improve undergraduate astronomy education and AI literacy. It found that structured AI integration can enhance learning and critical evaluation skills. The primary classification on arXiv for this paper is physics.ed-ph but it is cross-listed on astro-ph which qualifies it for consideration.

The overlay for this one is here:

The official version of the paper can be found on arXiv here and the Fediverse announcement here:

https://fediscience.org/@OJ_Astro/116368195945602700

Next one up, the third paper of the week, also published on Wednesday 8th April, is “Statistical Predictions of the Accreted Stellar Halos around Milky Way-Like Galaxies” by J. Sebastian Monzon & Frank C. van den Bosch (Yale University, USA) and Martin P. Rey (University of Bath, UK). This one was published in the section Astrophysics of Galaxies; it describes new model to track formation of stellar halos in Milky Way-like galaxies, revealing their sensitivity to the fate of the largest satellite and whether accretion is early or late.

The overlay for this one is here:

The final, accepted version can be found on arXiv here and the Mastodon announcement is here:

The fourth paper this week, published on Thursday 9th April is “A Tale of Tails: Star Formation and Stripping in Jellyfish Galaxies in the Strong Lensing Cluster MACS J0138.0-2155” by Catherine C. Gibson, Jackson H. O’Donnell and Tesla E. Jeltema (UC Santa Cruz, USA). This investigates the effects of ram-pressure stripping on four galaxies, focusing on their stellar and gas kinematics, star formation rates, and galactic structure and is published in the folder marked Astrophysics of Galaxies.

The overlay is here:

The finally accepted version of this paper can be found here and the Mastodon announcement is here:

https://fediscience.org/@OJ_Astro/116374103962641944

The fifth and final paper for this week is “Investigating ionising sources and the complex interstellar medium of GHZ2 at z=12.3” by M. Castellano (INAF Osservatorio Astronomico di Roma, Italy) and 29 others based all around the world. This was also published on Thursday 9th April in the folder Astrophysics of Galaxies. The paper uses deep observations of galaxy GHZ2 to explore the sources of ionising radiation and interstellar medium properties at cosmic dawn. Findings suggest a stratified environment and a hard ionising radiation component.

The overlay for this one is here:

The officially-accepted version of this one can be found on arXiv here and the Mastodon announcement is here

https://fediscience.org/@OJ_Astro/116374246020924265

That concludes this week’s update. I’ll do another one at the end of next week, when the Easter vacations will be over.

Weekly Update from the Open Journal of Astrophysics – 07/02/2026

It’s Saturday once more so time for another update of activity at the Open Journal of Astrophysics. Since the last update we have published a further six papers, bringing the number in Volume 9 (2026) to 24 and the total so far published by OJAp up to 472.

I will continue to include the posts made on our Mastodon account (on Fediscience) to encourage you to visit it. Mastodon is a really excellent service, and a more than adequate replacement for X/Twitter which nobody should be using; these announcement also show the DOI for each paper.

The first paper to report this week is “The Impact of Star Formation and Feedback Recipes on the Stellar Mass and Interstellar Medium of High-Redshift Galaxies” by Harley Katz (U. Chicago, USA), Martin P. Rey (U. Oxford, UK), Corentin Cadiou (Lund U., Sweden) Taysun Kimm (Yonsei U., Korea) and Oscar Agertz (Lund). This paper was published on Monday 2nd February 2026 in the folder Astrophysics of Galaxies. It introduces MEGATRON, a new model for galaxy formation simulations, highlighting that feedback energy controls star formation at high redshift and highlighting the importance of the interstellar medium.

The overlay is here:

You can find the officially accepted version on arXiv here and the announcement on Fediverse here:

https://fediscience.org/@OJ_Astro/116000695648050758

The second paper is “Photometric Redshifts in JWST Deep Fields: A Pixel-Based Alternative with DeepDISC” by Grant Merz (U. Illinois at Urbana-Champaign) and 6 others, all based in the USA. This paper was published on Monday February 2nd 2026 in the folder Instrumentation and Methods for Astrophysics. This paper explores the effectiveness of the DeepDISC machine learning algorithm in estimating photometric redshifts from near-infrared data, demonstrating its potential for larger image volumes and spectroscopic samples

The overlay for this one is here:

The official version of the paper can be found on arXiv here and the Fediverse announcement here:

https://fediscience.org/@OJ_Astro/116000777572439111

Next, published on Wednesday 4th February in the folder Astrophysics of Galaxies, is “Inferring Interstellar Medium Density, Temperature, and Metallicity from Turbulent H II Regions” by Larrance Xing (U. Chicago, USA), Nicholas Choustikov (U. Oxford, UK), Harley Katz (U. Chicago) and Alex J. Cameron (DAWN, Denmark). This paper argues that supersonic turbulenc affects the interpretation of H II region properties, potentially impacting inferred metallicity, ionization, and excitation from in nebular emission lines, motivating more extensive modelling.

The overlay is here:

The official version can be found on arXiv here and the Fediverse announcement is here:

https://fediscience.org/@OJ_Astro/116011384659092223

The fourth paper this week, also published on Wednesday 4th February, but in the folder Solar and Stellar Astrophysics, is “A Systematic Search for Big Dippers in ASAS-SN” by B. JoHantgen, D. M. Rowan, R. Forés-Toribio, C. S. Kochanek, & K. Z. Stanek (Ohio State University, USA), B. J. Shappee (U. Hawaii, USA), Subo Dong (Peking University), J. L. Prieto Universidad Diego Portales, Chile) and Todd A. Thompson (Ohio State). This study identifies 4 new dipper stars and 15 long-period eclipsing binary candidates using ASAS-SN light curves and multi-wavelength data, categorizing them based on their characteristics.

Here is the overlay:

The official version can be found on arXiv here and the Fediverse announcement is here:

https://fediscience.org/@OJ_Astro/116011460612040834

Fifth, and next to last this week we have “Unveiling the drivers of the Baryon Cycles with Interpretable Multi-step Machine Learning and Simulations” by Mst Shamima Khanom, Benjamin W. Keller and Javier Ignacio Saavedra Moreno (U. Memphis, USA). This paper was published on Thursday 5th February 2026 in the folder Astrophysics of Galaxies. This study uses machine learning methods to understand how galaxies lose or retain baryons, highlighting the relationship between baryon fraction and various galactic measurements.

The overlay is here:

The accepted version can be found on arXiv here, and the fediverse announcement is here:

https://fediscience.org/@OJ_Astro/116016883984380622

Finally for this week we have “The Bispectrum of Intrinsic Alignments: II. Precision Comparison Against Dark Matter Simulations” by Thomas Bakx (Utrecht U., Netherlands), Toshiki Kurita (MPA Garching, Germany), Alexander Eggemeier (U. Bonn, Germany), Nora Elisa Chisari (Utrecht) and Zvonimir Vlah (Ruđer Bošković Institute, Croatia). This paper was accepted in December, but publication got delayed by the Christmas effect so was published on February 6th 2026, in the folder Cosmology and Nongalactic Astrophysics. This study uses N-body simulations to accurately measure three-dimensional bispectra of halo intrinsic alignments and dark matter overdensities, providing a method to determine higher order shape bias parameters.

The overlay is here:

You can find the published version of the article here, and the Mastodon announcement is here:

https://fediscience.org/@OJ_Astro/116022562915557971

And that concludes this week’s update. I will do another next Saturday.

NASA Telescopes Spot Surprisingly Mature Cluster in Early Universe https://www.nasa.gov/missions/chandra/nasa-telescopes-spot-surprisingly-mature-cluster-in-early-universe/ #NASA #ChandraXRayObservatory #Astrophysics #Galaxies #GalaxyClusters #MarshallAstrophysics #MarshallSpaceFlightCenter #TheUniverse

NASA’s Chandra Rings in New Year With Champagne Cluster https://www.nasa.gov/missions/chandra/nasas-chandra-rings-in-new-year-with-champagne-cluster/ #NASA #ChandraXRayObservatory #Astrophysics #Galaxies #GalaxyClusters #MarshallAstrophysics #MarshallSpaceFlightCenter #TheUniverse

NASA IXPE’s Longest Observation Solves Black Hole Jets Mystery https://www.nasa.gov/missions/ixpe/nasa-ixpes-longest-observation-solves-black-hole-jets-mystery/ #NASA #IXPEImagingXRayPolarimetryExplorer #Astrophysics #ChandraXRayObservatory #Galaxies #GalaxyClusters #MarshallAstrophysics #MarshallScienceProjects #MarshallScienceResearchProjects #MarshallSpaceFlightCenter #NeilGehrelsSwiftObservatory #TheUniverse

Galaxy clusters break MOND. They need ~1.7× more mass than predicted - modified gravity's biggest problem.

New paper: the enhancement comes from geometry. Hot plasma activates extra coupling channels (3 vs. 1 in cold galaxies).

√3 = 1.73. Matches data: 1.69 ± 0.39.
Predicts zero hydrostatic bias - testable with X-ray + lensing.

🔗 https://zenodo.org/records/17922206

@fqxi @Physics

#physics #astrophysics #cosmology #MOND #ModifiedGravity #GalaxyClusters #openscience #preprint #DarkMatter

NASA IXPE’s Longest Observation Solves Black Hole Jets Mystery https://www.nasa.gov/missions/ixpe/nasa-ixpes-longest-observation-solves-black-hole-jets-mystery/ #NASA #IXPEImagingXRayPolarimetryExplorer #Astrophysics #ChandraXRayObservatory #Galaxies #GalaxyClusters #MarshallAstrophysics #MarshallScienceProjects #MarshallScienceResearchProjects #MarshallSpaceFlightCenter #TheUniverse #XRayAstronomy

NASA IXPE’s Longest Observation Solves Black Hole Jets Mystery

https://web.brid.gy/r/https://www.nasa.gov/missions/ixpe/nasa-ixpes-longest-observation-solves-black-hole-jets-mystery/

Decoding AGN Feedback with X-arithmetic - From Morphology to Physical Mechanisms: https://iopscience.iop.org/article/10.3847/1538-4357/adea67 -> Painting #GalaxyClusters by Numbers (and Physics): https://chandra.si.edu/photo/2025/xa/

Mapping Dark Matter https://www.nasa.gov/image-article/mapping-dark-matter/ #NASA #ChandraXRayObservatory #GalaxyClusters #JamesWebbSpaceTelescopeJWST

Cosmography archives

Large-scale superclusters surrounding the giant galaxy void in Boötes?

by Neta Bahcall and Raymond Soneira (1982)

https://ui.adsabs.harvard.edu/abs/1982ApJ...258L..17B/abstract

#Cosmography #Cosmology #galaxies #voids #BootesVoid #superclusters #galaxyclusters #archives #history #science #historyofscience #NetaBahcall #Astronomy #Astrophysics #Astrodon

NOIRLab image of the week

A Cluster of Interacting Galaxies (Abell 3754)

Credit: Dark Energy Survey/DOE/FNAL/DECam/CTIO/NOIRLab/NSF/AURA; Image processing: R. Colombari, M. Zamani (NSF NOIRLab) & T.A. Rector (University of Alaska Anchorage/NSF NOIRLab)

https://noirlab.edu/public/images/iotw2543a/

#galaxies #Abell3754 #astronomy #astrophysics #astrodon #DECam #galaxyclusters #cosmology #science #NOIRLab

Hubble Snaps Galaxy Cluster’s Portrait https://www.nasa.gov/image-article/hubble-snaps-galaxy-clusters-portrait/ #NASA #GalaxyClusters

Hubble Snaps Galaxy Cluster’s Portrait https://science.nasa.gov/missions/hubble/hubble-snaps-galaxy-clusters-portrait/ #NASA #Astrophysics #AstrophysicsDivision #Galaxies #GalaxyClusters #GoddardSpaceFlightCenter #GravitationalLensing #HubbleSpaceTelescope

Evolution of Cluster Alignments as Evidence of Large-scale Structure Formation in the Universe: https://iopscience.iop.org/article/10.3847/2041-8213/ade66d -> Galaxy Clusters Reveal Which Way Traffic Flows in the Universe: https://lowell.edu/cosmic-highways-galaxy-clusters-reveal-which-way-traffic-flows-in-the-universe/ - a new study finds that #GalaxyClusters trace invisible highways of dark matter stretching up to a billion light years across the universe; even more remarkable, the clusters point the way to their neighbors.

Bullet Cluster (Webb and Chandra Compass Image) ✨

#Cosmology #GalaxyClusters #GravitationalLensing #Multiwavelength

⏩ 3 new pictures from Webb (NASA) https://commons.wikimedia.org/wiki/Special:ListFiles?limit=5&user=OptimusPrimeBot&ilshowall=1&offset=20250701043453

Astronomers discover vast filament of ‘missing’ matter ✨🛰️

#Galaxyclusters #Xrays

▶️ 1 new picture from ESA https://commons.wikimedia.org/wiki/File:Astronomers_discover_vast_filament_of_%E2%80%98missing%E2%80%99_matter_ESA509961_-.png

PSZ2 G181.06+48.47 - X-Ray Exploration of / Radio Analysis of / Weak-lensing Analysis and Merging Scenario Reconstruction of a Low-mass Cluster with Exceptionally Distant Radio Relics: https://iopscience.iop.org/article/10.3847/1538-4357/adb731 / https://iopscience.iop.org/article/10.3847/1538-4357/adbbb9 / https://iopscience.iop.org/article/10.3847/1538-4357/adbc99 -> #GalaxyClusters on Course to Crash Again, NASA's Chandra Finds: https://chandra.si.edu/photo/2025/g181/ / https://www.nasa.gov/image-article/galaxy-clusters-on-course-to-crash-again-nasas-chandra-finds/

Galaxy Clusters on Course to Crash Again, NASA’s Chandra Finds https://www.nasa.gov/image-article/galaxy-clusters-on-course-to-crash-again-nasas-chandra-finds/ #NASA #ChandraXRayObservatory #Galaxies #GalaxyClusters #MarshallAstrophysics #MarshallSpaceFlightCenter #TheUniverse

Location of Euclid Deep Fields on Gaia and Planck sky map ✨🛰️

#Astronomy #Darkmatter #Galaxies #Galaxies,distant #Galaxy #Galaxyclusters #Gravity #Nebula

⏩ 7 new pictures from ESA https://commons.wikimedia.org/wiki/Special:ListFiles?limit=12&user=OptimusPrimeBot&ilshowall=1&offset=20250320064204

Galaxy clusters are the largest structures in the universe. Protoclusters like SPT2349-56 offer a unique window into this process, allowing astronomers to observe galaxies as they come together in a dense environment.

By comparing ALMA's high-resolution configuration observations with lower-resolution data from ALMA's Compact Array (ACA), and APEX, the team found a significant amount of molecular gas "invisible" in the higher-resolution ALMA images. The ACA detected 75% more CO than the sum of individual sources detected in higher-resolution ALMA data.

This missing gas isn't just a few faint, undetected galaxies. Instead, it appears to be a diffuse reservoir of gas spread throughout the protocluster.

This hidden gas reservoir could be the key to understanding the intense star formation activity observed in SPT2349-56. The presence of so much extra gas extends the star formation fuel, meaning the overall depletion timescale will exceed 400 million years.

SPT2349-56 is an extreme system, producing stars 10.000 times faster than our Milky Way, and these observations have pushed scientists' understanding of galaxy formation and evolution. No simulation or galaxy formation model had previously predicted this overdensity of gas. These findings also suggest that high-resolution ALMA observations, while excellent for studying individual galaxies, may miss a significant gas component in these early clusters. The missing gas may reside in the circum-galactic medium (CGM) or the pre-heated proto-intracluster medium (proto-ICM).

More information at https://www.almaobservatory.org/en/press-releases/alma-founds-hidden-cosmic-fuel/

#ALMA #AtacamaLargeMillimeterSubmillimeterArray #GalaxyClusters #StarFormation

I had the pleasure to be interviewed by Alexandre Morales for France Culture, to talk about the discovery of Quipu, one of the largest known structure of the Universe. It will air tomorrow morning at 6:52.

Here is the press release by the authors of the discovery at MPI Garching https://www.mpg.de/24197951/largest-superstructure-in-the-nearby-universe

#Quipu #QuipuSupercluster #Cosmology #Cosmography #galaxies #galaxyclusters #XrayClusters #ROSAT #CLASSIX #Astronomy #Astrophysics #Astrodon #science #STEM #news #AlexandreMorales #FranceCulture

Phoenix Cluster (Hubble, Chandra, VLA Annotated) ✨

#BlackHoles #GalaxyClusters

⏩ 2 new pictures from Webb (NASA) https://commons.wikimedia.org/wiki/Special:ListFiles?limit=4&user=OptimusPrimeBot&ilshowall=1&offset=20250214100125

New Simulated Universe Previews Panoramas From NASA’s Roman Telescope https://www.nasa.gov/universe/new-simulated-universe-previews-panoramas-from-nasas-roman-telescope/ #NASA #NancyGraceRomanSpaceTelescope #Astrophysics #DarkEnergy #DarkMatter #Galaxies #GalaxiesStarsBlackHoles #GalaxiesStarsBlackHolesResearch #GalaxyClusters #GoddardSpaceFlightCenter #HighTechComputing #ScienceResearch

Weekly Update from the Open Journal of Astrophysics – 11/01/2025

Welcome to the first update of 2025 from the It’s Saturday morning once again so here’s another quick update of activity at the Open Journal of Astrophysics. For the new year we have started Volume 8. Since the last update of 2024 we have published four new papers which brings the total so far published by OJAp up to 239.

In chronological order of publication, the four papers published this week, with their overlays, are as follows. You can click on the images of the overlays to make them larger should you wish to do so.

First one up is “Weak-Lensing Shear-Selected Galaxy Clusters from the Hyper Suprime-Cam Subaru Strategic Program: I. Cluster Catalog, Selection Function and Mass–Observable Relation” by Kai-Feng Chen (MIT, USA), I-Non Chiu (National Cheng University, Taiwan), Masamune Oguri (Chiba University, Japan), Yen-Ting Lin (IAAAS, Taiwan), Hironao Miyatake (Nagoya, Japan), Satoshi Miyazaki (Nat. Astr. Obs. Japan), Surhud More (IUCAA, India), Takashi Hamana (Nat. Astr. Obs. Japan), Markus M. Rau Carnegie Mellon University, USA), Tomomi Sunayama (Steward Obs., USA), Sunao Sugiyama (U. Penn, USA), Masahiro Takada (U. Tokyo, Japan).

This paper, which was published on Monday 6th January 2025 is in the folder Cosmology and NonGalactic Astrophysics, discusses steps towards towards the extraction of cosmogical constraints from a sample of galaxy clusters selected via weak gravitational lensing

Here is a screen grab of the overlay, which includes the abstract:

You can find the officially accepted version of the paper on the arXiv here.

The second paper to announce, published on 7th January 2025 and also in the folder Cosmology and NonGalactic Astrophysics, is “Cosmology on point: modelling spectroscopic tracer one-point statistics” by Beth McCarthy Gould (Newcastle U., UK), Lina Castiblanco (Bielefeld, Germany), Cora Uhlemann (Bielefeld, Germany), and Oliver Friedrich (LMU, Germany).

You can see the overlay here:

The accepted version of this paper can be found on the arXiv here.

The third paper, published on 9th January 2025, also in the folder Cosmology and NonGalactic Astrophysics, is “Probing Environmental Dependence of High-Redshift Galaxy Properties with the Marked Correlation Function” by Emy Mons and Charles Jose (Cochin University of Science and Technology, India). This paper uses the marked two-point correlation function to measure the environmental dependence of galaxy clustering at high redshift.

Here is the overlay:

The final version accepted on arXiv is here.

Last of this quartet, also published on 9th January 2025, but in the folder Astrophysics of Galaxies is “The infrared luminosity of retired and post-starburst galaxies: A cautionary tale for star formation rate measurements” by Vivienne Wild (St Andrews, UK), Natalia Vale Asari (Universidade Federal de Santa Catarina, Brazil), Kate Rowlands (STScI, Sara L. Ellison (U. Victoria, Canada), Ho-Hin Leung (St Andrews), Christy Tremonti (U. Wisconsin-Madison, USA).

The paper proposes an extension of the semi-analytic formalism to weak lensing and thermal Sunyaev-Zeldovich (tSZ) fields directly on the full-sky, with an emphasis on higher-order correlations. The overlay is here:

You can find the official accepted version on the arXiv here.

That’s all for this week. I’ll do another update next Saturday.

#arXiv240611966v2 #arXiv240908672v2 #arXiv240918182v2 #arXiv241212573v2 #cosmicShear #CosmologyAndNonGalacticAstrophysics #DiamondOpenAccess #galaxyClustering #galaxyClusters #markedTwoPointCorrelationFunction #onePointStatistics #starFormation #starburstGalaxies #Subarau #TheOpenJournalOfAstrophysics #weakGravitationalLensing

Illustration of the Firefly Sparkle Galaxy in the Early Universe (Artist's Concept) ✨

#Galaxies #GalaxyClusters #GravitationalLensing

⏩ 4 new pictures from Webb (NASA) https://commons.wikimedia.org/wiki/Special:ListFiles?limit=5&user=OptimusPrimeBot&ilshowall=1&offset=20241212100528

Found: First Actively Forming Galaxy as Lightweight as Young Milky Way https://science.nasa.gov/missions/webb/found-first-actively-forming-galaxy-as-lightweight-as-young-milky-way/ #NASA #Astrophysics #Galaxies #GalaxyClusters #GoddardSpaceFlightCenter #GravitationalLensing #JamesWebbSpaceTelescopeJWST #ScienceResearch #TheUniverse