Archive for the The Universe and Stuff Category

Astrophysics Wrapped 2025

Posted in Open Access, The Universe and Stuff with tags , , , , , on February 18, 2026 by telescoper

An interesting paper has appeared on the arXiv by Lewis, Shah & Alfred with the title Astrophysics Wrapped 2025: Year-in-Review of Every Astrophysics arXiv Paper from 2025 and abstract as follows:

Over the past few years, Astrophysics has experienced an unprecedented increase in research output, as is evident from the year-over-year increase in the number of research papers put onto the arXiv. As a result, keeping up with progress happening outside our respective sub-fields can be exhausting. While it is impossible to be informed on every single aspect of every sub-field, this paper aims to be the next best thing. We present a summary of statistics for every paper uploaded onto the Astrophysics arXiv over the past year – 2025. We analyse a host of metadata ranging from simple metrics like the number of pages and the most used keywords, as well as deeper, more interesting statistics like the distribution of journals to which papers are submitted, the most used telescopes, the most studied astrophysical objects including GW, GRB, FRB events, exoplanets and much more. We also indexed the authors’ affiliations to put into context the global distribution of research and collaboration. Combining this data with the citation information of each paper allows us to understand how influential different papers have been on the progress of the field this year. Overall, these statistics highlight the general current state of the field, the hot topics people are working on and the different research communities across the globe and how they function. We also delve into the costs involved in publications and what it means for the community. We hope that this is helpful for both students and professionals alike to adapt their current trajectories to better benefit the field.

The paper does what is says in the abstract and is well worth reading because it gives some fascinating insights into what’s hot in astrophysics, at least in terms of arXiv submissions which is probably a very good measure of activity because it is a truth universally acknowledged that every paper of interest in astrophysics is on ar|Xiv. I don’t intend to duplicate the whole paper here, as I think you should go and read it yourselves, but will pick out a couple of points.

One, near the start of the paper, is the following:

We begin with some general, overarching statistics from the year. As mentioned before, there were 18660 research papers published this year on the arXiv under the Astrophysics category in comparison to 16333 articles published in 2024. On average, there were 1555 papers per month, or about 72 papers per day, excluding weekends and accounting for the fact that arXiv uploads 5 days a week. 

This is a huge level of activity by any standard, especially as it does not include replacements or cross-submissions. As Editor of the Open Journal of Astrophysics it comes as no surprise to learn that the section `Astrophysics of Galaxies’ is the highest submitted primary subject category with 4761 papers submitted over the year and an average of 397 papers per month under this category. Interestingly, ‘Cosmology and Nongalactic Astrophysics’ papers have the highest number of citations across all indices, by some margin, despite having a lower number of papers submitted under this category. This tells us that while there might be fewer papers under this category, these papers are cited more on average, than the papers from any of the other categories. These are the two most popular categories for submissions at OJAp too.

For more interesting data on geographical distribution, citation rates, etc, read the text!

I also want to pick up on an issue mentioned near the end of the abstract, namely the absurd system of funding “Gold” Open Access by Article Processing Charges. Here is a quote:

We estimate the total amount of money spent in publishing to paid journals, assuming every paper is published under Gold Open Access. Our calculation takes into account the publishing fees for different journals, the cost per page where applicable, as well as discounted rates for authors from certain ‘member’ countries for specific journals. In total, we estimate the community spent 17 million USD on publishing fees this year. Counting only the papers that were published and ignoring the zero cost of open source journals, this rounds out to an absolutely ridiculous 2,400 USD per publication. If every astrophysics paper published on the arXiv in 2025 were to be published under the same standards (average cost from the previous calculation applied to every paper), that would mean a total cost of 45 million USD on publishing. These numbers are similar to those obtained in Coles (2025). Astrophysics is, according to our calculations, a multi-million dollar business, but for whom? Certainly not for the people who make it possible. Definitely not for the scientists and not for the general public.

(I added the link to my own post at the OJAp blog which is referred to in the article).

I agree wholeheartedly with the conclusion. The figure of 45 million dollars for the money wasted on APCs is nothing short of a scandal. Why does the astrophysics community put up with being fleeced in this way?

Here is another excerpt:

While it is nice to have the Open Journal of Astrophysics singled out for praise, the earlier statistics do put the situation in perspective. In 2025 OJAp published 213 papers using our arXiv overlay model. That’s only just over 1% of the overall arXiv submissions on astro-ph! As a community we need to be publishing via a Diamond Open Acess model by default. Given the scale of the problem The Open Journal of Astrophysics can’t achieve that goal on its own, but at least we’re showing that there is a way forward.

The Trouble with Teaching Particle Physics…

Posted in Education, The Universe and Stuff with tags , on February 16, 2026 by telescoper

The trouble with teaching particle physics is that students start out thinking that the standard model looks like this

when it’s really more like this

I hope this clarifies the situation.

Weekly Update from the Open Journal of Astrophysics – 14/02/2026

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , on February 14, 2026 by telescoper

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 30 and the total so far published by OJAp up to 478.

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 “Faraday Depolarization Study of a Radio Galaxy Using LOFAR Two-metre Sky Survey: Data Release 2” by Samantha Sneha Paul and Abhik Ghosh (Banwarilal Bhalotia College, India). This was published on Tuesday February 10th in the folder Cosmology and Nongalactic Astrophysics. The paper analyzes the depolarization of radio galaxy ILTJ012215.21+254334.8 using LOFAR’s Sky Survey data, revealing a preferred three-component model and highlighting turbulence in the magneto-ionic medium.

The overlay is here:

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

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "Faraday Depolarization Study of a Radio Galaxy Using LOFAR Two-metre Sky Survey: Data Release 2" by Samantha Sneha Paul and Abhik Ghosh (Banwarilal Bhalotia College, India)

doi.org/10.33232/001c.157500

February 10, 2026, 6:25 am 0 boosts 1 favorites

The second paper is “Rapid cosmological inference with the two-loop matter power spectrum” by Thomas Bakx (Utrecht U., NL), Henrique Rubira (Ludwig-Maximilians-Universität, DE), Nora Elisa Chisari (Utrecht) and Zvonimir Vlah (Ruđer Bošković Institute, Croatia). This was also published on Tuesday February 10th in the folder Cosmology and Nongalactic Astrophysics. This paper uses the COBRA method to compute the two-loop effective field theory power spectrum of dark matter density fluctuations, providing more precise cosmological constraints than the one-loop EFT.

The overlay for this one is here:

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

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "Rapid cosmological inference with the two-loop matter power spectrum" by Thomas Bakx (Utrecht U., NL), Henrique Rubira (Ludwig-Maximilians-Universität, DE), Nora Elisa Chisari (Utrecht) and Zvonimir Vlah (Ruđer Bošković Institute, Croatia)

doi.org/10.33232/001c.157501

February 10, 2026, 6:41 am 0 boosts 0 favorites

Next, published on Wednesday 11th February in the folder Astrophysics of Galaxies, is “Interpreting nebular emission lines in the high-redshift Universe” by Aswin P. Vijayan (U. Sussex, UK) and 9 others based in the UK, Taiwan, China and The Netherlands. This article examines the reliability of diagnostics used to estimate star formation rate and gas-phase oxygen abundance in high-redshift galaxies. It finds that variations in stellar populations and star-dust geometry. The overlay is here:

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

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "Interpreting nebular emission lines in the high-redshift Universe" by Aswin P. Vijayan (U. Sussex, UK) and 9 others based in the UK, Taiwan, China and The Netherlands

doi.org/10.33232/001c.157554

February 11, 2026, 8:21 am 0 boosts 0 favorites

The fourth paper this week, also published on Wednesday 11th February, but in the folder Instrumentation and Methods for Astrophysics is “Derivative-Aligned Anticipation of Forbush Decreases from Entropy and Fractal Markers” by Juan D. Perez-Navarro & David Sierra Porta (Universidad Tecnológica de Bolívar, Colombia). The paper presents a feature-based framework for predicting Forbush decreases, i.e. rapid, temporary drops in galactic cosmic ray (GCR) intensity (up to tens of percent) caused by solar wind disturbances, typically Coronal Mass Ejections (CMEs) or high-speed streams from coronal holes, in neutron-monitor records using various computational methods. The approach is reproducible, operates on native station units, and is stable.

Here is the overlay:

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

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "Derivative-Aligned Anticipation of Forbush Decreases from Entropy and Fractal Markers" by Juan D. Perez-Navarro & David Sierra Porta (Universidad Tecnológica de Bolívar, Colombia)

doi.org/10.33232/001c.157585

February 11, 2026, 5:19 pm 0 boosts 0 favorites

The fifth paper, the penultimate for this week, is “Supermassive black hole growth from stellar binary encounters” by Aubrey L Jones and Benjamin C Bromley (University of Utah, USA). This paper explores the growth of supermassive black holes (SMBHs) through stellar accretion via the Hill’s mechanism, predicting capture rates and identifying potential growth drivers in 91 galaxies. It was published on Thursday 11th February 2026 in the folder Astrophysics of Galaxies.

The overlay is here:

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

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "Supermassive black hole growth from stellar binary encounters" by Aubrey L Jones and Benjamin C Bromley (University of Utah, USA)

doi.org/10.33232/001c.157589

February 12, 2026, 7:31 am 1 boosts 2 favorites

Finally for this week we have “Dynamics in the Cores of Self-Interacting Dark Matter Halos: Reduced Stalling and Accelerated Core Collapse” by Frank C. van den Bosch and Shashank Dattathri (Yale University, USA). This study uses simulations to explore core dynamics in self-interacting dark matter (SIDM) halos. Findings suggest strong self-interactions prevent core stalling and buoyancy, leading to accelerated core collapse. This was published yesterday, on Friday 13th February 2026, in the folder Astrophysics of Galaxies.

The overlay is here:

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

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "Dynamics in the Cores of Self-Interacting Dark Matter Halos: Reduced Stalling and Accelerated Core Collapse" by Frank C. van den Bosch and Shashank Dattathri (Yale University, USA)

doi.org/10.33232/001c.157701

February 13, 2026, 8:27 am 1 boosts 2 favorites

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

Probabilistic inference in very large universes

Posted in The Universe and Stuff with tags , , , , on February 10, 2026 by telescoper

I came across a recent article on the arXiv with the title Probabilistic inference in very large universes by Feraz Azhar, Alan H. Guth, Mohammad Hossein Namjoo.

The paper discusses a conceptually challenging issue in cosmology, which I’ll put simply as follows. Suppose we have two cosmological theories: A, which describes a very large universe in only a tiny part of which low-energy physics turns out like ours; and B in which we have a possibly much smaller universe in which low-energy physics is like ours with a high probability. Can we determine whether A or B is the “better” theory, and if so how?

The abstract of the paper is below:

Some cosmological theories propose that the observable universe is a small part of a much larger universe in which parameters describing the low-energy laws of physics vary from region to region. How can we reasonably assess a theory that describes such a mostly unobservable universe? We propose a Bayesian method based on theory-generated probability distributions for our observations. We focus on basic principles, leaving aside concerns about practicality. (We also leave aside the measure problem, to discuss other issues.) We argue that cosmological theories can be tested by standard Bayesian updating, but we need to use theoretical predictions for “first-person” probabilities — i.e., probabilities for our observations, accounting for all relevant selection effects. These selection effects can depend on the observer, and on time, so in principle first-person probabilities are defined for each observer-instant — an observer at an instant of time. First-person probabilities should take into account everything the observer believes about herself and her surroundings — i.e., her “subjective state”. We advocate a “Principle of Self-Locating Indifference” (PSLI), asserting that any real observer should make predictions as if she were chosen randomly from the theoretically predicted observer-instants that share her subjective state. We believe the PSLI is intuitively very reasonable, but also argue that it maximizes the expected fraction of observers who will make correct predictions. Cosmological theories will in general predict a set of possible universes, each with a probability. To calculate first-person probabilities, we argue that each possible universe should be weighted by the number of observer-instants in the specified subjective state that it contains. We also discuss Boltzmann brains, the humans/Jovians parable of Hartle and Srednicki, and the use of “old evidence”.

arXiv:2602.02667

I haven’t had time to read the paper in detail yet, and I don’t think I’m going to agree with all of it when I do, but I found it sufficiently stimulating to share here in the hope that others will find it interesting.

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

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , on February 7, 2026 by telescoper

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:

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "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)

doi.org/10.33232/001c.156097

February 2, 2026, 11:02 am 1 boosts 1 favorites

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:

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "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

doi.org/10.33232/001c.156099

February 2, 2026, 11:23 am 1 boosts 0 favorites

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:

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "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)

doi.org/10.33232/001c.156223

February 4, 2026, 8:20 am 1 boosts 0 favorites

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:

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "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)

doi.org/10.33232/001c.156224

February 4, 2026, 8:40 am 1 boosts 0 favorites

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:

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "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)

doi.org/10.33232/001c.156271

February 5, 2026, 7:39 am 1 boosts 1 favorites

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:

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "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)

doi.org/10.33232/001c.156361

February 6, 2026, 7:43 am 1 boosts 0 favorites

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

Weekly Update from the Open Journal of Astrophysics – 31/01/2026

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , , , , , , , , , , , , , , , , , , , , , , , , on January 31, 2026 by telescoper

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 four papers, bringing the number in Volume 9 (2026) to 18 and the total so far published by OJAp up to 466.

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 “Probing Stellar Kinematics with the Time-Asymmetric Hanbury Brown and Twiss Effect” by Lucijana Stanic (University of Zurich, Switzerland) and 13 others based in Zurich, Lausanne and Geneva (all in Switzerland). This was published on Monday 26th January 2026 in the folder Instrumentation and Methods for Astrophysics. This research demonstrates that intensity interferometry can reveal internal stellar kinematics, providing a new way to observe stellar dynamics with high time resolution.

The overlay is here:

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

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "Probing Stellar Kinematics with the Time-Asymmetric Hanbury Brown and Twiss Effect" by Lucijana Stanic (University of Zurich, Switzerland) and 13 others based in Zurich, Lausanne and Geneva.

doi.org/10.33232/001c.155802

January 26, 2026, 11:46 am 0 boosts 1 favorites

The second paper is “DIPLODOCUS I: Framework for the evaluation of relativistic transport equations with continuous forcing and discrete particle interactions” by Christopher N Everett & Garret Cotter (University of Oxford, UK). This was published on Tuesday January 27th 2026 in the folder High-Energy Astrophysical Phenomena. DIPLODOCUS is a new framework for mesoscopic modelling of astrophysical systems, using an integral formulation of relativistic transport equations and a discretisation procedure for particle distributions.

The overlay for this one is here:

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

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "DIPLODOCUS I: Framework for the evaluation of relativistic transport equations with continuous forcing and discrete particle interactions" by Christopher N Everett & Garret Cotter (University of Oxford, UK)

doi.org/10.33232/001c.155822

January 27, 2026, 8:49 am 1 boosts 0 favorites

Next, also published on Tuesday January 27th but in the folder Cosmology and Nongalactic Astrophysics we have “The Atacama Cosmology Telescope: DR6 Sunyaev-Zel’dovich Selected Galaxy Clusters Catalog” by M. Aguena et al. (101 authors altogether), on behalf of the ACT-DES-HSC Collaboration. This article reports on the discovery of 10,040 galaxy clusters in the Atacama Cosmology Telescope data, including 1,180 clusters at high redshifts, using the Sunyaev-Zel’dovich effect.

The overlay is here:

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

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "The Atacama Cosmology Telescope: DR6 Sunyaev-Zel’dovich Selected Galaxy Clusters Catalog" by M. Aguena et al. (101 authors altogether), on behalf of the ACT-DES-HSC Collaboration

doi.org/10.33232/001c.155863

January 27, 2026, 9:55 am 1 boosts 0 favorites

And finally for this week we have a paper published yesterday, Friday 30th January 2026, in the folder Astrophysics of Galaxies. This is the paper I blogged about yesterday: “A Cosmic Miracle: A Remarkably Luminous Galaxy at zspec = 14.44 Confirmed with JWST” by Rohan Naidu (MIT Kavli Institute) and an international cast of 45 others. This article reports on the discovery by the James Webb Space Telescope (JWST) of a bright galaxy, MoM-z14, located 280 million years post-Big Bang, that challenges models of galaxy formation and the star-formation history of early galaxies.

The overlay is here:

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

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "A Cosmic Miracle: A Remarkably Luminous Galaxy at $z_{rm spec} = 14.44$ Confirmed with JWST" by Rohan Naidu (MIT Kavli Institute) and 45 others.

doi.org/10.33232/001c.156033

January 30, 2026, 7:20 am 2 boosts 1 favorites

And that concludes the update for this week. I will do another next Saturday.

A Cosmic Miracle?

Posted in OJAp Papers, The Universe and Stuff with tags , , , , , on January 30, 2026 by telescoper

A while ago (last May, in fact) I posted an article about a galaxy with an apparent spectroscopic redshift of 14.44. The paper to which that post related had been submitted to the Open Journal of Astrophysics and I haven’t mentioned that paper again until now as the paper was then, so to speak, sub judice. Well, as of today, the paper is now published and will feature in tomorrow’s traditional Saturday roundup of publications at the journal.

This paper was in fact accepted for publication before Christmas, but it took until this morning for the final accepted article to reach the arXiv. Rather awkwardly, the Space Telescope Science Institute issued a press release about this paper on 28th January 2026 stating that the paper was published in the Open Journal of Astrophysics, when that statement was not accurate. As Editor-in Chief of the Open Journal of Astrophysics, I was subsequently contacted by a number of journalists asking where they could find the paper on the OJAp platform. Since it hadn’t been published then I had to say they couldn’t, so a number of pieces (including, for example, this one in Scientific American) have appeared based on the STSCi press release without links to the final version of the paper. It would have been far better, in my opinion, to have delayed the press release until the paper was actually published. It’s better to wait until the ball is in the back of the net before you start celebrating!

Anyway, thanks to me getting up at 6am today, it’s now published so there’s no real harm done.

The fediscience announcement is here:

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "A Cosmic Miracle: A Remarkably Luminous Galaxy at $z_{rm spec} = 14.44$ Confirmed with JWST" by Rohan Naidu (MIT Kavli Institute) and 45 others.

doi.org/10.33232/001c.156033

January 30, 2026, 7:20 am 1 boosts 0 favorites

For reference, here is the key plot showing the spectrum from which the galaxy’s redshift is determined. It is rather noisy, but the Lyman break seems convincing and there are some emission lines that offer corroborative evidence:

Weekly Update from the Open Journal of Astrophysics – 24/01/2026

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , , , , , , , , , , , , , , on January 24, 2026 by telescoper

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 three papers, bringing the number in Volume 9 (2026) to 14 and the total so far published by OJAp up to 462. This week was slightly affected by a Federal holiday in the USA on January 19th; there were no arXiv announcements the following day.

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.

The first paper to report this week is “The Properties of Little Red Dot Galaxies in the ASTRID Simulation” by Patrick LaChance, Rupert A. C. Croft, Tiziana Di Matteo & Yihao Zhou (Carnegie Mellon U.), Fabio Pacucci (Harvard-Smithsonian CfA), Yueying Ni (U. Michigan Ann Arbor), Nianyi Chen (Princeton U.) and Simeon Bird (UC Riverside), all based in the USA. This paper was published on Monday 19th January 2026 in the folder Cosmology and Nongalactic Astrophysics; the study analyses mock observations of “Little Red Dot” galaxies created from the ASTRID simulation, having high stellar masses and containing massive black holes; not all features match real observations.

The overlay is here:

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

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics; "The Properties of Little Red Dot Galaxies in the ASTRID Simulation" by Patrick LaChance, Rupert A. C. Croft, Tiziana Di Matteo & Yihao Zhou (Carnegie Mellon U.), Fabio Pacucci (Harvard-Smithsonian CfA), Yueying Ni (U. Michigan Ann Arbor), Nianyi Chen (Princeton U.) and Simeon Bird (UC Riverside), all based in the USA

doi.org/10.33232/001c.155493

January 19, 2026, 10:33 am 2 boosts 1 favorites

The second paper is “Angular bispectrum of matter number counts in cosmic structures” by Thomas Montandon (U. Montpellier, France), Enea Di Dio (U. Genève, Switzerland), Cornelius Rampf (Ruđer Bošković Institute, Croatia) and Julian Adamek (U. Zürich, Switzerland). This was published on Wednesday January 21st, also in the folder Cosmology and Nongalactic Astrophysics. This paper presents thee first full-sky computation of the angular bispectrum in second-order perturbation theory, offering insights into the Universe’s initial conditions, gravity, and cosmological parameters. The results align well with simulations.

The overlay for this one is here:

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

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "Angular bispectrum of matter number counts in cosmic structures" by Thomas Montandon (U. Montpellier, France), Enea Di Dio (U. Genève, Switzerland), Cornelius Rampf (Ruđer Bošković Institute, Croatia) and Julian Adamek (U. Zürich, Switzerland)

doi.org/10.33232/001c.155624

January 21, 2026, 9:30 am 1 boosts 0 favorites

Next, and last for this week, we have “The Kinematic Properties of TŻO Candidate HV 11417 with Gaia DR3” by Anna J. G. O’Grady (Carnegie Mellon University, USA). This was published on Wednesday 21st January 2026 in the folder Solar and Stellar Astrophysics. This work uses updated data to confirm that HV 11417, a potential Thorne-Żytkow Object, is probably part of the Small Magellanic Cloud and qualifies as a runaway star.

The overlay is here:

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

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "The Kinematic Properties of TŻO Candidate HV 11417 with Gaia DR3" by Anna J. G. O'Grady (Carnegie Mellon University, USA)

doi.org/10.33232/001c.155625

January 21, 2026, 9:45 am 1 boosts 1 favorites

That concludes the update for this week. I will do another next Saturday.

Dark Energy Survey Year Y6 Results Day!

Posted in The Universe and Stuff with tags , , , , , , on January 22, 2026 by telescoper

This morning’s arXiv announcement contained a number of papers related to the Dark Energy Survey Y6 analysis. There is also a Zoom webinar later today at 10.30 Central Time (16.30 GMT; 13.30 in Greenland). Details can be found here.

You can find links to and abstracts of all the papers here, but I thought it would be useful to provide arXiv links to the latest batch here.

  • arXiv:2601.14559 Dark Energy Survey Year 6 Results: Cosmological Constraints from Galaxy Clustering and Weak Lensing – this is the key summary paper.
  • arXiv:2601.14484 Dark Energy Survey Year 6 Results: MagLim++ Lens Sample Selection and Measurements of Galaxy Clustering
  • arXiv:2601.14864 Dark Energy Survey: DESI-Independent Angular BAO Measurement
  • arXiv:2601.15175 Dark Energy Survey Year 6 Results: Galaxy-galaxy lensing
  • arXiv:2601.14833 Dark Energy Survey Year 6 Results: Magnification modeling and its impact on galaxy clustering and galaxy-galaxy lensing cosmology
  • arXiv:2601.14859 Dark Energy Survey Year 6 Results: Weak Lensing and Galaxy Clustering Cosmological Analysis Framework

A number of DES Y6 papers already published – including several in the Open Journal of Astrophysics – are listed here.

I’ll just highlight a couple of points from the first paper listed above, which uses the now standard “3x2pt” analysis, which combines three complementary two-point correlation functions: cosmic shear; galaxy-galaxy lensing and galaxy clustering. The abstract of this paper is as follows:

A notable result is contained in the last sentence. The simplest interpretation of dark energy is that it is a cosmological constant (usually called Λ) which – as explained here – corresponds to a perfect fluid with an equation-of-state p=wρc2 with w=-1. In this case the effective mass density  ρ of the dark energy remains constant as the universe expands. To parametrise departures from this constant behaviour, cosmologists have replaced this form with the form w(a)=w0+wa(1-a) where a(t) is the cosmic scale factor. A cosmological constant Λ would correspond to a point (w0=-1, wa=0) in the plane defined by these parameters, but the only requirement for dark energy to result in cosmic acceleration is that w<-1/3, not that w=-1. Results last year from DESI suggested values of w0 ≠-1 and wa≠0 , but the current DES results are consistent with w=-1; they do not constrain w0 and wa jointly.

For reference on the left you can find the (w0, wa) plane from DESI.

I thought I’d add one of the other cosmological contraint plots:

The results look qualitatively similar to previous plots but the contours have shifted a bit.

The growth of light seed black holes in the early Universe

Posted in Maynooth, The Universe and Stuff with tags , , , , , 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: