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Weekly Update from the Open Journal of Astrophysics 25/07/2026

It’s time once more for another Saturday update of activity at the Open Journal of Astrophysics. Since the last update we have published a further nine papers, bringing the number in Volume 9 (2026) to 160 and the total so far published by OJAp up to 608.

I will continue to include the posts made on our Mastodon account (on Fediscience); these announcements also show the DOI for each paper.

The first paper to report this week was published on Tuesday 21st July in the folder Cosmology and Nongalactic Astrophysics. The title is “Characterization of the Polarization Beam Response of SPT-3G Using Point Sources” by Tijmen de Haan (Institute of Particle and Nuclear Studies, Ibaraki, Japan) and an international cast of 101 others. This study presents measurements of the South Pole Telescope’s polarized beam response, indicating minimal sidelobe depolarization. The findings suggest potential explanations for frequency-dependent residuals in power spectrum analysis.

The overlay for this paper is here

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

The second paper for this week, also published on Tuesday 21st July but in the folder Earth and Planetary Astrophysics is: “Exploring TRAPPIST-1 Climate States with an Energy Balance Model” by Jacob Haqq-Misra (Blue Marble Space, USA). The study uses a modified HEXTOR energy balance model to predict climate states of terrestrial planets orbiting low-mass stars, suggesting partial to complete ice cover for TRAPPIST-1 e and f.Abstractfor Exploring TRAPPIST-1 Climate States with an Energy Balance Model.

The overlay looks like this:

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

The third paper of the week, also published on Tuesday 21st July, but in the folder Astrophysics of Galaxies is “A first systematic study of [OIII] 88μm at z>8: two luminous oxygen lines and a powerful ionized outflow in the first 600 million years” by Hiddo Algera (Institute of Astronomy and Astrophysics, Taipei, Taiwan) and 37 others from all around the world. This paper presents deep observations of four UV-bright, gravitationally lensed galaxies, revealing an ionized outflow in one and highlighting the diagnostic power of [O III]88 μm in studying galaxies in the early Universe.

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 of the week, published on Thursday 23rd July in the folder Astrophysics of Galaxies, is “Mapping CO Ice in a Star-Forming Filament in the 3 kpc Arm with JWST” by Savannah Gramze (U. Florida, USA) and 16 others based all around the world. This paper shows that JWST observations and ALMA Band 3 data reveal that 50-88% of CO gas in a star-forming filament is locked in ice; corrections are needed for mass measurements in such systems.

The overlay for this one is here:

You can read the final version of this one on arXiv here and the Mastodon announcement is here:

The fifth paper of the week, also published on Thursday 23rd July but in the folder High-Energy Astrophysical Phenomena, is “Viscously Spreading Accretion Disks around Black Holes: Implications for TDEs, LFBOTs and other Transients“. This article presents a time-dependent model of accretion disks around black holes, explaining late-time emission in tidal disruption events and luminous fast blue optical transients and future detectability of such events.

The overlay for this one is here:

You can read the final version of this one on arXiv here and the Mastodon announcement is here:

The sixth paper of this week is “Characterising the response of an International LOFAR Station” by Letizia Vincetti (Trinity Collge Dublin, Ireland) and 9 others based in Ireland, USA, The Netherlands and Sweden. This was also published on Thursday July 23rd and is in the folder Instrumentation and Methods for Astrophysics. The article presents an investigation of the performance and calibration challenges of phased-array radio interferometers, using the Irish LOFAR station as a case study, highlighting the importance of accurate beam modelling, etc.

The overlay for this one is here:

You can find the final accepted version on arXiv here and the Mastodon announcement is here:

The seventh paper of this week is “Exo Skryer: A JAX-accelerated sub-stellar atmospheric retrieval framework” by Elspeth K.H. Lee (U. Bern, Switzerland). Published on Friday 24th July in the folder Earth and Planetary Astrophysics, this article introduces “Exo Skryer”, a new, efficient framework for exoplanet and brown dwarf atmospheric research, capable of handling large data sets and complex models.

The overlay for this one is here:

You can find the final accepted version on arXiv here and the Mastodon announcement is here:

The (penultimate) eighth paper of this week is “GCR Spectra Reconstructed with Neutron Monitor Yield Function and Artificial Neural Networks: Comparison of Two Methods” by Stepan A. Siruk (Moscow Engineering Physics Institute MEPhI, Russia) and four others, all based in Russia. Published on Friday 24th July in the folder Instrumentation and Methods for Astrophysics, this article presents a framework using artificial neural networks and neutron monitors to reconstruct cosmic-ray energy spectra, providing data even in the absence of direct satellite observations.

The overlay for this one is here:

You can find the final accepted version on arXiv here and the Mastodon announcement is here:

And finally for this week we have “The failed failed-supernova scenario of M31-2014-DS1” by Noam Soker (Technion, Israel), a paper which challenges the failed-supernova theory for the fading of the yellow supergiant event M31-2014-DS1, suggesting it requires unlikely parameters and supports an alternative scenario involving violent binary interaction. This was published on Friday 24th July in the folder High-Energy Astrophysical Phenomena.

The overlay for this one is here:

You can find the final accepted version on arXiv here and the Mastodon announcement is here:

And that concludes the update of this week’s business. As it was foretold, the total number of publications at OJAp has now passed the 600 mark, and the likely number for 2026 is around 300. We published a paper in five of the six astro-ph categories this week, but still haven’t had a week when we’ve published a full house with at least one in all six…

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Weekly Update from the Open Journal of Astrophysics 04/07/2026

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags accretion disks, arXiv:2411.15112v4, arXiv:2505.12671v2, arXiv:2507.17742v2, arXiv:2511.07066v2, arXiv:2512.10613v2, arXiv:2605.14065v2, arXiv:2606.11293v2, Astrophysics of Galaxies, baryon acoustic oscillations, baryon feedback, black hole mergers, black holes, cosmic inflation, Cosmic Microwave Background, Cosmology, Cosmology and NonGalactic Astrophysics, Diamond Open Access, Diamond Open Access Publishing, fast radio bursts, Fermi Bubbles, gamma-ray astronomy, High-Energy Astrophysical Phenomena, hypervelocity runaways, magnetic fields, magnetic turbulence, Open Access, Open Access Publishing., Plasma Physics, Solar and Stellar Astrophysics, thermonuclear supernovae on July 4, 2026 by telescoper

It’s Saturday again so it’s time for another update of activity at the Open Journal of Astrophysics. Since the last update we have published a further seven papers, bringing the number in Volume 9 (2026) to 136 and the total so far published by OJAp up to 584.

I will continue to include the posts made on our Mastodon account (on Fediscience); these announcements also show the DOI for each paper.

The first paper to report this week, published on Monday 29th June, is “Analysis and implications of the spatio-spectral morphology of the Fermi Bubbles” by Ami Tank (Indian Institute of Technology) and Roland Crocker & Mark R. Krumholz (Australian National University). Published in the folder High-Energy Astrophysical Phenomena, this paper presents an analysis of the gamma-ray structures of Fermi Bubbles in the Milky Way using a decade of data. The research suggests either hadronic or leptonic processes can explain the data.

The overlay for this paper is here

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

The second paper for this week, also published on Monday 29th June, but in the folder Cosmology and Nongalactic Astrophysics, is “A first measurement of baryonic feedback with Fast Radio Bursts” by Robert Reischke (Universität Bonn, Germany) and Steffen Hagstotz (Ludwig-Maximilians Universität München, Germany). This paper argues that Fast Radio Bursts (FRBs) provide a new method to trace baryon distribution and feedback in the cosmos, offering insights into matter distribution and rejecting no-feedback scenarios with high confidence.

The overlay looks like this:

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

The third paper of the week, published on Tuesday 30th June in the folder High-Energy Astrophysical Phenomena, is “Idealized Global Models of Accretion Disks with Strong Toroidal Magnetic Fields” by Minghao Guo & Eliot Quataert (Princeton U., USA), Jonathan Squire (U. Otago, NZ), Philip F. Hopkins (Caltech, USA) and James M. Stone (Princeton). This study uses global magnetohydrodynamic simulations to explore the behavior of idealized accretion disks with strong toroidal magnetic fields, finding that these systems maintain a moderately strong mean azimuthal field.

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 of the week, published on Tuesday 30th June in the folder High-Energy Astrophysical Phenomena, is “On the effective spin-mass ratio relation of binary black hole mergers that evolved in isolation” by Sambaran Banerjee (Helmholtz-Instituts für Strahlen und Kernphysik, Germany) and Aleksandra Olejak (MPA Garching, Germany). This study explores mechanisms of binary black hole mergers and finds that certain spin and mass ratio trends can be naturally explained by isolated binary evolution. The overlay for this one is here:

You can read the final version of this one on arXiv here and the Mastodon announcement is here:

The fifth paper of the week, also published on Tuesday 30th June but in the folder Solar and Stellar Astrophysics is “A systematic survey for hypervelocity runaways from thermonuclear supernovae” by Kareem El-Badry (Caltech, USA), and 18 others based in the USA, Germany, Austria and the UK. This paper presents a systematic survey of hypervelocity runaways, resulting from white dwarf explosions in binary systems. The findings suggest a diversity of remnant masses, ages, and heating mechanisms, challenging theoretical models.

The overlay for this one is here:

You can read the final version of this one on arXiv here and the Mastodon announcement is here:

The sixth and penultimate paper of this week is “Boris and Exponential Integrators in the Theory of Particles Interacting with Magnetic Turbulence” by Andreas Shalchi (U. Manitoba, Canada). This was published on Wednesday 1st July, in the folder Solar and Stellar Astrophysics (it is posted in the plasma physics section of aXiv but cross-listed in solar and stellar astrophysics). The study compares the Rodrigues and Boris integrators in test-particle simulations of charged particles interacting with magnetic fields, finding both methods yield similar results.

The overlay for this one is here:

You can find the final accepted version on arXiv here and the Mastodon announcement is here:

The seventh and final paper for this week is “Inflation at the End of 2025: Constraints on $r$ and $n_S$ using the Latest CMB and BAO Data” by Lennart Balkenhol (Institut d’Astrophysique de Paris, France) and 12 others based in France, Italy, Switzerland, UK, USA and Australia. This was also published on Wednesday 1st July, in the folder Cosmology and Nongalactic Astrophysics. This study presents constraints on parameters of inflationary models in cosmology, using the latest cosmic microwave background and baryon acoustic oscillation data. The findings help differentiate between inflation models.

The overlay for this one is here:

You can find the final accepted version of this one on arXiv here and the Mastodon announcement is here:

And that concludes this week’s update. We’re starting to catch up on the backlog generated in June. At just past the halfway point of the year, which is where we are, we’re on 136 papers, which suggests a total around 272 for the year.

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Weekly Update from the Open Journal of Astrophysics 20/06/2026

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags arXiv:2510.00292v5, arXiv:2602.09104v2, arXiv:2603.15899v2, arXiv:2604.07336v2, Astrophysics of Galaxies, black holes, collisional rings, Copula, Cosmic Dawn, cosmological surveys, Cosmology and NonGalactic Astrophysics, Diamond Open Access, Diamond Open Access Publishing, galaxy mergers, Ice, Interstellar Medium, JWST, non-Gaussianity, Open Access, Open Access Publishing., photometry, SEEDZ simulations, SN2025adpq, spectroscopy, Type 1a Supernovae, weak gravitational lensing on June 20, 2026 by telescoper

It’s Saturday again so it’s time for another update of activity at the Open Journal of Astrophysics. Since the last update we have published a further three papers, bringing the number in Volume 9 (2026) to 126 and the total so far published by OJAp up to 574.

I will continue to include the posts made on our Mastodon account (on Fediscience); these announcements also show the DOI for each paper.

The first paper to report this week, published on Monday 15th June, is “SN 2025adpq: A Type Ia supernova in a collisional ring formed during a major galaxy merger” by Brendan O’Connor (Carnegie Mellon University, USA) and 18 others based in the USA, Germany and Australia. The study reports the discovery of a Type Ia supernova, SN 2025adpq, within a collisional ring formed by a major galaxy merger., offset from the nucleus of the primary galaxy. It is published in the folder Astrophysics of Galaxies.

The overlay for this paper is here

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

The second paper for this week, published on Tuesday June 16th in the folder Astrophysics of Galaxies is “The Colors of Ices: Measuring ice column density through photometry” by Adam Ginsburg (U. Florida, USA) and ten others based in the USA, Germany and Spain. This study demonstrates that JWST photometry can identify and quantify interstellar ices, using new open-source models, interstellar ices, finding significant abundance in non-star-forming gas, suggesting many avenues for further research.

The overlay looks like this:

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

The third paper of the week, published on Wednesday 17th June in the folder Cosmology and Nongalactic Astrophysics is “The Non-Gaussian Weak-Lensing Likelihood: A Multivariate Copula Construction and Impact on Cosmological Constraints” by Veronika Oehl and Tilman Tröster (both of ETH Zurich, Switzerland). This study presents a framework for computing non-Gaussian likelihoods for correlation functions, particularly useful in large-scale weak-lensing surveys. It suggests Gaussian likelihoods are sufficient for stage-IV surveys.

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 and final paper of the week, also ublished on Wednesday 17th June but in the folder Astrophysics of Galaxies, is “Black Hole Feedback, Galaxy Quenching and Outflows at Cosmic Dawn: Analysis of the SEEDZ Simulations” by Lewis R. Prole (Maynooth University, Ireland) and 15 others based in Ireland, Germany, USA and UK. The study analyzes the growth and feedback effects of massive black holes in SEEDZ simulations, suggesting that black hole feedback, not nearby supernovae or gas exhaustion, limits initial growth.

The overlay is here:

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

And that concludes this week’s update. It has been a slow week on the publishing front, but the main reason is that we have a big backlog of papers accepted but waiting for the authors to put their final versions on arXiv and we can’t do anything about that! I’ll do another update next Saturday.

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The growth of light seed black holes in the early Universe

Posted in Maynooth, The Universe and Stuff with tags black holes, Daxal Mehta, Department of Physics, John Regan, Lewis Prole, Maynooth University on January 21, 2026 by telescoper

Meanwhile, back in the world of research, I see that Maynooth University has issued a news item about a new paper by colleagues in the Department of Physics, Daxal H. Mehta, John A. Regan and Lewis Prole. The story has also been picked up by the Irish media, e.g. here.

You may find the paper behind a paywall, as it is published in Nature Astronomy, in which case you will just have to make do with the abstract:

And here’s a pretty picture from one of the simulations used in the paper:

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Black Holes, Hawking Radiation (and AI…)

Posted in Artificial Intelligence, The Universe and Stuff with tags black holes, GenAI, Google, Hawking Radiation, Hawking Temperature, supermassive black holes on December 7, 2025 by telescoper

It seems to be a common misapprehension that the energy released by the supermassive black holes in, for example, active galactic nuclei is in the form of Hawking radiation. It isn’t. Hawking radiation is only significant for black holes of very low mass. The radiation produced around supermassive black holes is due to the extremely high density and temperate of matter falling into the black hole through an accretion disk not due to the evaporation of the black hole itself. Hawking radiation has never been experimentally detected.

Hawking showed that the a black hole will produce black-body radiation with a temperature, the Hawking Temperature, given by T_H in a beautiful formula below that brings together constants relating to gravity, statistical mechanics, quantum theory and relativity:

You can see that the Hawking Temperature is inversely proportional to the mass of the black hole M so is largest for very small black holes. In fact for a black hole with mass of order that of the Moon, the Hawking Temperature is just 3 Kelvin. Since the Universe is bathed in cosmic radiation with this temperature, such a black hole would not evaporate at all because it would absorb as much radiation as it emits by the Hawking mechanism as would any black hole of mass greater than this. The Hawking temperature for a supermassive black hole is many orders of magnitude lower than this, so Hawking radiation is completely irrelevant.

Notice that if a black hole does start to evaporate then its mass begins to decrease. Its Hawking temperature therefore increases so its mass decreases even more quickly. In the end the mass gets so low and the temperature so high that the black hole effectively explodes. Nobody really knows how to describe the final stage as it relies on physics we don’t understand.

Anyway, this all reminds that years ago I set an examination question that involved applying the Hawking formula above to calculate the lifetime of a black hole of mass M. It’s not too hard to show that it scales as M^-3. Another part of the question asked: what is the mass of a black hole whose Hawking Temperature is room temperature (say 300 K), what would be the Schwarzschild radius of such a black hole, and what would be its lifetime?

I’ll leave it to my readers to plug the numbers into the Hawking formula above to derive the mass, etc. Please submit your answers through the comments box below. The first correct entry does not win a prize, not even a joke Peace Prize.

For a laugh I asked Google for the answer. Here is the AI summary:

Bonus marks for pointing out everything that’s wrong in this summary.

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In-Tray

Posted in Biographical with tags black holes, in-tray, industry on November 25, 2025 by telescoper

Yesterday I came across the old cartoon shown above and shared it on Bluesky. It seemed to cause some amusement so I thought I’d share it here too.

The in-tray reminds me of when I (briefly) worked in industry during the 80s. There was a guy in our large open-plan office who had two trays on his desk, one with a sign marked “IN” and the other with a sign marked “OUT”. Things were delivered on Mondays to the in-trays and collected from out-trays at the end of the day on Fridays. This guy never touched the stuff in his in-tray but just before he left work on Fridays he would swap the signs on the two trays…

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Weekly Update from the Open Journal of Astrophysics – 15/11/2025

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags 2504.19510v2, arXiv:2405.18468v2, arXiv:2501.01578v2, arXiv:2504.19510v2, arXiv:2505.04731v2, arXiv:2507.00757v2, arXiv:2509.07695v2, arXiv:2509.09764v3, Astrophysics of Galaxies, black holes, Cosmology, Cosmology and NonGalactic Astrophysics, Diamond Open Access, Diamond Open Access Publishing, downsizing, dynamical friction, Explosion, galaxy formation, gravitational microlensing, High-Energy Astrophysical Phenomena, jittering jets, JWST, M31, neutrinos, Open Access, Open Journal of Astrophysics, redshift drift, splashback radius, supernovae, The Open Journal of Astrophysics on November 15, 2025 by telescoper

It’s Saturday again, so it’s time for the usual update of the week’s new papers at the Open Journal of Astrophysics. It has been quite a busy week. Since the last update we have published another seven papers, which brings the number in Volume 8 (2025) up to 175, and the total so far published by OJAp up to 410.

First on the menu for this week is “Dynamical friction and measurements of the splashback radius in galaxy clusters” by Talia M. O’Shea (U. Wisconsin-Madison, USA), Josh Borrow & Stephanie O’Neil (U. Pennsylvania, USA) and Mark Vogelsberger (MIT, USA). Published on Tuesday 11th November in the folder Cosmology and NonGalactic Astrophysics, this one presents a study suggesting that dynamical friction does not play a major role in reducing the radius of the splashback feature in real data compared to numerical simulations.

The overlay is here:

You can find the officially accepted version on arXiv here.

The Fediverse announcement is here:

Open Journal of Astrophysics

@OJ_Astro@fediscience.org

New Publication at the Open Journal of Astrophysics: "Dynamical friction and measurements of the splashback radius in galaxy clusters" by Talia M. O'Shea (U. Wisconsin-Madison, USA), Josh Borrow & Stephanie O'Neil (U. Pennsylvania, USA) and Mark Vogelsberger (MIT, USA)

https://doi.org/10.33232/001c.147125

November 11, 2025, 8:36 am 3 boosts 1 favorites

The second paper of the week is “Microlensing of lensed supernovae Zwicky & iPTF16geu: constraints on the lens galaxy mass slope and dark compact object fraction” by Nikki Arendse (Stockholm University, Sweden) and and international cast of 11 others based in Sweden, UK and France. This one was published on 11th November 2025 in the folder Astrophysics of Galaxies. It is about combining observations of two supernovae, iPTF16geu and SN Zwicky, with microlensing magnification maps to probe the properties of the lens galaxy.

The overlay is here:

You can find the official version of this one on arXiv here. The federated announcement on Mastodon is here:

Open Journal of Astrophysics

@OJ_Astro@fediscience.org

New Publication at the Open Journal of Astrophysics: "Microlensing of lensed supernovae Zwicky & iPTF16geu: constraints on the lens galaxy mass slope and dark compact object fraction" by Nikki Arendse (Stockholm University, Sweden) and 11 others based in Sweden, UK and France

https://doi.org/10.33232/001c.147126

November 11, 2025, 8:53 am 1 boosts 1 favorites

Next one up is “Neutrino Constraints on Black Hole Formation in M31” by Yudai Sawa (U. Tokyo, Japan) and 11 others all based in Japan. This was published on Tuesday 11th November in the folder High-Energy Astrophysical Phenomena. It presents a calculation of the neutrino emission expected from the collapse of massive stars and its use in constraining black hole formation using neutrino detectors.

The overlay is here:

You can find the official accepted version on arXiv here. The fediverse announcement is here:

Open Journal of Astrophysics

@OJ_Astro@fediscience.org

New Publication at the Open Journal of Astrophysics: "Neutrino Constraints on Black Hole Formation in M31" by Yudai Sawa (U. Tokyo, Japan) and 11 others all based in Japan

https://doi.org/10.33232/001c.147127

November 11, 2025, 9:04 am 0 boosts 1 favorites

The fourth paper this week is “Redshift Drift in Relativistic N-Body Simulations” by Alexander Oestreicher (U. Southern Denmark, DK), Chris Clarkson (QMUL, UK), Julian Adamek (U. Zürich, CH) and Sofie Marie Koksbang (U. Southern Denmark, DK). This one was published on Wednesday 12th November in the folder marked Cosmology and NonGalactic Astrophysics. It presents numerical calculations of the cosmological redshift drift effect for comparison with future surveys.

The overlay is here:

You can find the official published version on arXiv here. The Fediverse announcement follows:

Open Journal of Astrophysics

@OJ_Astro@fediscience.org

New Publication at the Open Journal of Astrophysics: "Redshift Drift in Relativistic N-Body Simulations" by Alexander Oestreicher (U. Southern Denmark, DK), Chris Clarkson (QMUL, UK), Julian Adamek (U. Zürich, CH) and Sofie Marie Koksbang (U. Southern Denmark, DK)

https://doi.org/10.33232/001c.147178

November 12, 2025, 8:35 am 1 boosts 0 favorites

The fifth paper for this week is “Attributing the point symmetric structure of core-collapse supernova remnant N132D to the jittering jets explosion mechanism” by Noam Soker (Technion, Haifa, Israel). This one, published on Wednesday November 12th in the folder High-Energy Astrophysical Phenomena, presents a discussion of the morphology of a supernova remnant and possible explanation for it in terms of the explosion mechanism.

The overlay is here:

The officially accepted version can be found on arXiv here. The Fediverse announcement is here:

Open Journal of Astrophysics

@OJ_Astro@fediscience.org

New Publication at the Open Journal of Astrophysics: "Attributing the point symmetric structure of core-collapse supernova remnant N132D to the jittering jets explosion mechanism" by Noam Soker (Technion, Haifa, Israel)

https://doi.org/10.33232/001c.147183

November 12, 2025, 8:46 am 1 boosts 0 favorites

The sixth paper to report this week is “Witnessing downsizing in the making: quiescent and breathing galaxies at the dawn of the Universe” by Emiliano Merlin (Osservatorio Astronomico di Roma, Italy) and an international cast of 20 others based in Italy, Germany, UK, USA, Switzerland, Spain and China. This one was published on Friday November 14th in the folder Astrophysics of Galaxies.

You can find the officially-accepted version on arXiv here. The fediverse announcement is here:

Open Journal of Astrophysics

@OJ_Astro@fediscience.org

New Publication at the Open Journal of Astrophysics: "Witnessing downsizing in the making: quiescent and breathing galaxies at the dawn of the Universe" by Emiliano Merlin (Osservatorio Astronomico di Roma, Italy) and 20 others based in Italy, Germany, UK, USA, Switzerland, Spain and China

https://doi.org/10.33232/001c.147267

November 14, 2025, 8:38 am 1 boosts 1 favorites

And finally (for this week) we have “Beyond No No Tension: JWST z > 10 Galaxies Push Simulations to the Limit” by Joe McCaffrey (NUI Maynooth, Ireland), Samantha Hardin & John Wise (Georgia Institute of Technology, USA) and John Regan (Maynooth). This one was also published on Friday 14th November, in the folder marked Astrophysics of Galaxies. It asks the question whether newly-discovered high redshift galaxies are consistent with simulations of galaxy formation. The overlay is here:

You can find the officially acceopted version on arXiv here. The fediverse announcement is here:

Open Journal of Astrophysics

@OJ_Astro@fediscience.org

New Publication at the Open Journal of Astrophysics: "Beyond No No Tension: JWST z > 10 Galaxies Push Simulations to the Limit" by Joe McCaffrey (NUI Maynooth, Ireland), Samantha Hardin & John Wise (Georgia Institute of Technology, USA) and John Regan (Maynooth)

https://doi.org/10.33232/001c.147278

November 14, 2025, 9:02 am 2 boosts 0 favorites

And that concludes the update for this week. There will be another next Saturday.

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A Decade of Gravitational Waves

Posted in Biographical, The Universe and Stuff with tags Advanced LIGO, arXiv:2508.18082, Black hole merger, black holes, gravitational waves, GW150914, inspiral on September 14, 2025 by telescoper

This is just a quick post to mark the fact that it is now ten years to the day since the first detection of gravitational waves by Advanced LIGO. The acronym LIGO stands for Laser Interferometer Gravitational-wave Observatory, by the way. It wasn’t until February 11th 2016 that the result was announced at a press conference (which I blogged about here), but the signal itself arrived on 14th September 2015, exactly a decade ago; the name given to the event was GW150914.

Here are the plots for that first one:

That first signal corresponded to the coalescence of two black holes, of masses 29 and 36 times the mass of the Sun and produced a large response in the detectors very soon after Advanced LIGO was switched on. There’s synchronicity for you! The LIGO collaboration have done wondrous things getting their sensitivity down to such a level that they can measure such a tiny effect, but there still has to be an event producing a signal to measure. Collisions of two such massive black holes are probably extremely rare so it’s a bit of good fortune that one happened just at the right time. Actually it was during an engineering test.

There have been many subsequent detections and even more candidates waiting to be confirmed- here’s a full list. The official LIGO site states there are 90 confirmed detections, the 4th observational run (O4) (which is due to end in November 2025) has already found 200 candidates. The latest compilation of gravitational-wave transient sources can be found here.

Most of the detections have been binary black hole mergers, but I particularly remember the excitement in 2017 surrounding the first merger of a neutron star with a black hole. It was fun that rumours started to spread via this blog as people outside the LIGO/transient source community used a comments thread here to share information of what various telescopes were looking at. That was in August 2017, just over 8 years ago.

Anyway, here’s to the next decade. Assuming NSF does not follow Trump’s plan to slash the LIGO budget.

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Galaxies and Black Holes in the First Billion Years

Posted in Biographical, The Universe and Stuff with tags arXiv:2508.16948, black holes, Cosmology, galaxy formation, JWST, Richard Ellis on September 1, 2025 by telescoper

Trying to catch up on recent developments in galaxy formation? I can heartily recommend an excellent review article on the subject by Richard Ellis which you can find on the arXiv here. The abstract reads:

I present written notes from three lectures given at the 54th Saas-Fee Advanced Course of the Swiss Society of Astrophysics and Astronomy in January 2025 entitled “Galaxies and Black Holes in the First Billion Years as seen by the JWST”. I focused my lectures on progress in studies of cosmic reionisation, the properties of galaxies in the reionisation era, topics related to the redshift frontier and the search for Population III stars. The lectures were given to graduate students in astrophysics and cover both pedagogical material as well as observational results from the first two and half years of JWST science operations. The pace of discovery with JWST is, of course, rapid and so my lectures discuss long-term goals, analysis methods and their assumptions and limitations in the hope that the underlying material will retain value in the near future. In this written version, the visual material is that presented at Saas-Fee in January 2025 but I have provided updates on progress from the literature up to August 2025. The material is aimed at early career researchers and should not be considered as a scholarly review of the entire JWST literature on high redshift galaxies.

It’s quite a long article (65 pages) but nicely written and well worth reading, as it is full of information about recent advances as well as historical insights. Talking of which, there’s a picture on page 41 taken at a meeting in Durham in 1988 called The Epoch of Galaxy Formation that I attended while I was still a graduate student:

Richard Ellis himself is in the front row, left of centre with light-coloured trousers, checked shirt and hands in pockets. I’m in the picture too, but I’ll leave it up to you to find me!

A poll was held among the delegates at that meeting about various questions to do with galaxy formation. The majority opinions revealed by these votes nearly all turned out to be utterly wrong! That’s progress, I guess…

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Primordial Black Holes in Cosmological Simulations – Update

Posted in Maynooth, The Universe and Stuff with tags arXiv:2506.11233, black holes, primordial black holes on August 28, 2025 by telescoper

Just time for a quick update about a paper that I posted about at the start of the summer, when it appeared on arXiv. At that time it had already gained a bit of traction in the media, e.g. here. Well, the paper is now published in the Open Journal of Astrophysics. Obviously, as an author I was conflicted so not involved in the editorial process.

Here is the overlay:

For those of you not in the field, there is currently a big mystery about how galaxies we have found at high redshift with JWST managed to acquire massive black holes so early in the Universe’s evolution. Black holes can grow quickly in a dense environment by accreting mass onto an initial seed, but what are the seeds? In this paper we investigate the possibility that they were primordial black holes. These form directly from fluctuations in the early Universe, as opposed to astrophysical black holes which form from stellar collapse. We don’t know exactly what mass primordial black holes would have nor how numerous they would be, but this paper uses high-resolution numerical experiments to investigate their effects if they do exist.

Here’s a pretty picture which is a zoom into 200 pc of the full simulation. I think 10pc counts as high resolution for a cosmological simulation! The blue circle shows the most massive PBH in the simulation, the green circle shows its nearest neighbour. The colour scale represents the number-density of dark matter particles.

For more details, read the paper!

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