It’s Saturday once again, 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 110 and the total so far published by OJAp up to 558.
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 18th May in the folder Instrumentation and Methods for Astrophysics is “Edges In Coadded Images” by Erin Sheldon (Brookhaven National Laboratory, USA). This paper describes a study exploring how image discontinuities and noise impact weak gravitational lensing measurements, finding no significant biases under typical conditions. Biases occur only in extreme cases, but can be mitigated.
The overlay for this paper is here
You can find the officially accepted version on arXiv here and the announcement on Fediverse here:
New Publication at the Open Journal of Astrophysics: "Joint cosmological fits to DESI-DR1 full-shape clustering and weak gravitational lensing in configuration space " by A. Semenaite (Swinburne Institute of Technology, Australia) and 72 others from all round the world.
Next one up, the third paper of the week, and the third published on Monday 18th May, and in the folder Cosmology and Nongalactic Astrophysics is “Probing Dark Energy Microphysics with kSZ Tomography” by Julius Adolff, Selim Hotinli and Neal Dalal (all of the Perimeter Institute, Canada). This paper explores how kinetic Sunyaev-Zel’dovich tomography and galaxy clustering can enhance our understanding of dark energy and its effects, potentially revealing its microphysical properties in future surveys.
The overlay for this one is here:
The final, accepted version can be found on arXiv here and the Mastodon announcement is here:
New Publication at the Open Journal of Astrophysics: "Probing Dark Energy Microphysics with kSZ Tomography" by Julius Adolff, Selim Hotinli and Neal Dalal (Perimeter Institute, Canada)
The fourth paper this week, published on Wednesday May 20th is “A Census of Variable Radio Sources at 3 GHz” by Yjan A. Gordon, Peter S. Ferguson, Michael N. Martinez and Eric J. Hooper (all of the University of Wisconsin, USA). This article, published in the folder Astrophysics of Galaxies, uses data from the Very Large Array Sky Survey to analyze variability in the radio sky, finding most changes consistent with blazars and quasars.
The overlay is here:
The officially accepted version can be found on arXiv here and here is the Mastodon announcement:
New Publication at the Open Journal of Astrophysics: "A Census of Variable Radio Sources at 3 GHz" by Yjan A. Gordon, Peter S. Ferguson, Michael N. Martinez & Eric J. Hooper (U. Wisconsin, USA)
The fifth article of this week was published on Friday 22nd May in the folder Instrumentation and Methods for Astrophysics. The title is “Uncovering the Next Galactic Supernova with the Vera C. Rubin Observatory” by John Banovetz (Lawrence Berkeley Lab., USA), Claire-Alice Hebert & Peter B. Denton (Brookhaven National Lab., USA), Dan Scolnic (Duke University, USA), Anze Slosar (Brookhaven) and Chris Walter (Duke). The paper presents a study simulating how effectively the Vera C. Rubin Observatory can localize supernovae using neutrino triggers, finding a 57-97% success rate based on stellar mass density predictions.
The overlay is here:
You can find the authorized version of this paper on arXiv here and the Fediverse announcement is here:
New Publlication at the Open Journal of Astrophysics: "Uncovering the Next Galactic Supernova with the Vera C. Rubin Observatory" by John Banovetz (Lawrence Berkeley Lab., USA), Claire-Alice Hebert & Peter B. Denton (Brookhaven National Lab., USA) , Dan Scolnic (Duke U., USA) , Anze Slosar (Brookhaven), and Chris Walter (Duke)
Last, but by no means least, this week we have “Pulsar timing solutions for 17 pulsars at 150 MHz from the Irish LOFAR station” by David J. McKenna (ASTRON, The Netherlands), Evan F. Keane (Trinity College Dublin, Ireland), Peter T. Gallagher (DIAS, Ireland) and Joe McCauley (Trinity). This was published on Friday 22nd May in the folder High-Energy Astrophysical Phenomena. It presents a demonstration of the use of international Low Frequency Array (LOFAR) stations in tracking and characterizing pulsars, providing new insights into these neutron stars’ emission properties.
The overlay for this one is here:
You can find the authorized version of this paper on arXiv here and the Fediverse announcement is here:
New Publication at the Open Journal of Astrophysics: "Pulsar timing solutions for 17 pulsars at 150 MHz from the Irish LOFAR station" by David J. McKenna (ASTRON, The Netherlands), Evan F. Keane (Trinity College Dublin, Ireland), Peter T. Gallagher (DIAS, Ireland) and Joe McCauley (Trinity)
It’s Saturday once again, so time for another 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 104 and the total so far published by OJAp up to 552. It took us until late July to pass 100 last year.
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, published on Monday 11th May in the folder High-Energy Astrophysical Phenomena is “Triaxial magnetars as sources of fast radio bursts” by Jonathan I Katz (Washington University, USA). This paper suggests that the mysterious properties of Fast Radio Bursts (FRB) could be explained by triaxial magnetars, with their activity levels influenced by precessional time scales.
The overlay for this paper is here
You can find the officially accepted version on arXiv here and the announcement on Fediverse here:
New Publication at the Open Journal of Astrophysics: "Triaxial magnetars as sources of fast radio bursts" by Jonathan I Katz (Washington University, USA)
The second paper for this week, published on Tuesday 12th May in the folder Astrophysics of Galaxies, is “The Abundance of Thin Dwarf Galaxies: a Challenge for Cosmological Simulations” by Jose Benavides & Laura V. Sales (UC Riverside, USA), Julio F. Navarro (U. Victoria, Canada), Simon D. M. White (MPA Garching, Germany), and Carlos S. Frenk, Kyle A. Oman & Shaun Cole (U. Durham, UK). Depending on mass up to 40% of galaxies are intrinsically flat, a fraction that numerical models of galaxy formation struggle to reproduce suggesting the models are incomplete.
The overlay for this one is here:
The official version of the paper can be found on arXiv here and the Fediverse announcement here:
New Publication at the Open Journal of Astrophysics: "The Abundance of Thin Dwarf Galaxies: a Challenge for Cosmological Simulations" by Jose Benavides & Laura V. Sales (UC Riverside, USA), Julio F. Navarro (U. Victoria, Canada), Simon D. M. White (MPA Garching, Germany), and Carlos S. Frenk, Kyle A. Oman & Shaun Cole (U. Durham, UK)
Next one up, the third paper of the week, also published on Tuesday 12th May but in the folder Cosmology and Nongalactic Astrophysics is “Cosmological peculiar velocities in general relativity” by Chris Clarkson (Queen Mary, University of London, UK) and Roy Maartens (U. Western Cape, South Africa). This paper refutes claims that the 1+3 covariant approach to cosmological perturbation theory predicts stronger growth of galaxy peculiar velocities, arguing that standard treatments are correct and fully relativistic.
The overlay for this one is here:
The final, accepted version can be found on arXiv here and the Mastodon announcement is here:
New Publication at the Open Journal of Astrophysics: "Cosmological peculiar velocities in general relativity" by Chris Clarkson (QMUL, UK) and Roy Maartens (U. Western Cape, South Africa)
The fourth paper this week, published on Wednesday May 13th “Possible evidence for a pair-instability supernova nature of ultra-early JWST sources” by Andrea Ferrara & Stefano Carniani (Scuola Normale Superiore, Pisa, Italy), Takahiro Morishita (California Institute of Technology, USA), and Massimo Stiavelli (Space Telescope Science Institute, USA). Published in the section Astrophysics of Galaxies. This paper argues that recent observations challenge early galaxy formation models, suggesting that the bright source, Capotauro, could be a supernova from a massive, metal-free star, not a luminous galaxy as initially thought.
The overlay is here:
The officially accepted version can be found on arXiv here and here is the Mastodon announcement:
New Publication at the Open Journal of Astrophysics: "Possible evidence for a pair-instability supernova nature of ultra-early JWST sources" by Andrea Ferrara & Stefano Carniani (Scuola Normale Superiore, Pisa, Italy), Takahiro Morishita (Caltech, USA) and Massimo Stiavelli (STScI, USA)
The fifth and final article of this week was also published on Wednesday 13th May but in the folder Cosmology and Nongalactic Astrophysics. The title is “Evolving and interacting dark energy: photometric and spectroscopic synergy with DES Y3 and DESI DR2” and it is by Maria Tsedrik and Benjamin Bose (University of Edinburgh, UK). The study investigates the Dark Scattering interacting dark energy scenario, using data from various sources. Results show no evidence of dark-sector interaction and a preference for the Chevallier-Polarski-Linder parametrisation.
The overlay is here:
You can find the authorized version of this paper on arXiv here and the Fediverse announcement is here:
New Publication at the Open Journal of Astrophysics: "Evolving and interacting dark energy: photometric and spectroscopic synergy with DES Y3 and DESI DR2" by Maria Tsedrik and Benjamin Bose (University of Edinburgh, UK)
Here we are, on schedule, with 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 94 and the total so far published by OJAp up to 542. I checked the corresponding update for last year (on 3rd May 2025), and we’ve had an increase from 54 to 94 in papers published (about 74%) between the first four months of 2025 and the first four months of 2026.
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 “DESI-DR1 3 × 2-pt analysis: consistent cosmology across weak lensing surveys” by Anna Porredon (CIEMAT, Madrid, Spain) and 72 others (DESI Colllaboration). This paper was published on Tuesday 28th April in the folder Cosmology and Nongalactic Astrophysics. This paper presents a joint cosmological analysis of galaxy clustering and gravitational lensing observations, providing consistent constraints on cosmological parameters. The analysis also introduces a new blinding procedure to prevent confirmation bias. See this post for news of an important DESI milestone.
The overlay for this paper is here
You can find the officially accepted version on arXiv here and the announcement on Fediverse here:
New Publication at the Open Journal of Astrophysics: "DESI-DR1 3 × 2-pt analysis: consistent cosmology across weak lensing surveys" by Anna Porredon (CIEMAT, Madrid, Spain) and 72 others (DESI Colllaboration)
The second paper for this week, also published on Tuesday 28th April but in the folder High-Energy Astrophysical Phenomena is “Masers and Broad-Line Mapping Favor Magnetically-Dominated AGN Accretion Disks” by Philip F. Hopkins (Caltech, USA), Dalya Baron (Stanford U., USA) and Joanna M. Piotrowska (Caltech). This one presents a new constraint on supermassive black hole accretion disks physics, suggesting that outer regions are likely in a ‘hyper-magnetized’ state, as thermal or radiation pressure models appear inconsistent.
The overlay for this one is here:
The official version of the paper can be found on arXiv here and the Fediverse announcement here:
New Publication at the Open Journal of Astrophysics: "Masers and Broad-Line Mapping Favor Magnetically-Dominated AGN Accretion Disks" by Philip F. Hopkins (Caltech, USA), Dalya Baron (Stanford U., USA) and Joanna M. Piotrowska (Caltech)
Next one up, the third paper of the week, is “Galaxy mergers and disk angular momentum evolution: stellar halos as a critical test” by Eric F. Bell (U. Michigan, Ann Arbor, USA), Richard D’Souza (Vatican Observatory), Monica Valluri & Katya Gozman (U. Michigan). This was published on Wednesday 29th April in the folder Astrophysics of Galaxies. The paper argues that satellite accretion impacts the angular momentum evolution of galaxies, often causing significant reorientation. This process is detectable in Milky Way-mass galaxies so the idea is testable observationally.
The overlay for this one is here:
The final, accepted version can be found on arXiv here and the Mastodon announcement is here:
New Publication at the Open Journal of Astrophysics: "Galaxy mergers and disk angular momentum evolution: stellar halos as a critical test" by Eric F. Bell (U. Michigan, Ann Arbor, USA), Richard D'Souza (Vatican Observatory), Monica Valluri & Katya Gozman (U. Michigan)
The fourth paper this week, published on Thursday April 30th, is “Time-Dilation Methods for Extreme Multiscale Timestepping Problems” by Philip F. Hopkins and Elias R. Most (Caltech, USA). This paper is in the folder Instrumentation and Methods for Astrophysics: it presents a new method for astrophysical simulations that modulates time evolution with a variable dilation/stretch factor, improving efficiency and accuracy in modeling processes across different scales.
The overlay is here:
The finally accepted version of this paper can be found here and the Mastodon announcement follows:
New Publication at the Open Journal of Astrophysics: "Time-Dilation Methods for Extreme Multiscale Timestepping Problems" by Philip F. Hopkins and Elias R. Most (Caltech, USA)
The fifth article of this week was also published on Thursday 30th April, but in the folder Astrophysics of Galaxies. The title is “Cosmic Rays on Galaxy Scales: Progress and Pitfalls for CR-MHD Dynamical Models” and the author is Philip F. Hopkins (Caltech, USA) who has three papers featured this week. The paper presents an overview of cosmic ray (CR) modeling, highlighting its influence on galactic physics and star formation. It addresses previous modeling errors and presents new methods for full-spectrum dynamics.
The overlay is here:
You can find the authorized version of this paper on arXiv here and the Fediverse announcement is here:
New Publication at the Open Journal of Astrophysics: "Cosmic Rays on Galaxy Scales: Progress and Pitfalls for CR-MHD Dynamical Models" by Philip F. Hopkins (Caltech, USA)
New Publication at the Open Journal of Astrophysics: "Baryonification III: An accurate analytical model for the dispersion measure probability density function of fast radio bursts" by MohammadReza Torkamani (Universität Bonn, Germany) and 8 others based in Germany, Switzerland, UK and Sweden
New Publication at the Open Journal of Astrophysics: "The stellar and dark matter distributions in early-type galaxies measured by stacked weak gravitational lensing" by Momoka Fujikawa & Masamune Oguri (Chiba University, Japan)
Yesterday the Open Journal of Astrophysics published a paper by Porredon et al which will feature in the usual Saturday round-up. That paper, which is based on the First Data Release from the Dark Energy Spectroscopic Instrument (DESI) reminded me that I should mention that DESI recently reached an amazing milestone – it has now mapped the positions and redshifts of 47 million galaxies and quasars! There is a full press-release about this achievement here.
Here’s a little video showing how the survey works:
Here’s a nice picture showing a thin slice through the full survey that reveals the characteristic “cosmic web” of the large-scale structure of the Universe in all its glory:
This progress is great, but it really makes me feel old. Forty years ago, in 1986, I had just started my PhD. The state-of-the-art galaxy redshift survey slice then is shown in this plot, from de Lapparent et al 1986 (ApJLett 302, L1), one of the first papers I read as a research student (I got it in 1985 as a preprint), which contains just 1,100 galaxies:
It is worth mentioning that although DESI has now covered its original target area, it will continue until 2028. You can never have too many galaxy redshifts!
It’s Saturday once more, so it’s time for another update of activity at the Open Journal of Astrophysics. It has been a busy week. Since the last update we have published a further nine papers, bringing the number in Volume 9 (2026) to 45 and the total so far published by OJAp up to 493.
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 four papers this week were all published on Monday 23rd February.
New Publication at the Open Journal of Astrophysics: "A Bayesian Exploration of The Mass of the Ursa Major III: Kinematics, Rotation and their influence on the Mass to Light Ratio" by Tim R. Adams (U. Sydney, Australia), Brendon J. Brewer (U. Auckland, New Zealand) and Geraint F. Lewis (Sydney)
The second paper is “The Impact of Baryonic Effects on the Dynamical Masses Inferred Using Satellite Kinematics” by Josephine F.W. Baggen, Frank C. van den Bosch, and Kaustav Mitra (Yale U., USA). This paper, also in the folder Astrophysics of Galaxies, presents a model to assess the impact of stars and gas on satellite kinematics, showing that these baryonic effects can reduce the satellite velocity dispersion and increase inferred central galaxy masses.
The overlay for this one is here:
The official version of the paper can be found on arXiv here and the Fediverse announcement here:
New Publication at the Open Journal of Astrophysics: "The Impact of Baryonic Effects on the Dynamical Masses Inferred Using Satellite Kinematics" by Josephine F.W. Baggen, Frank C. van den Bosch, and Kaustav Mitra (Yale U., USA)
The third paper this week, and the third published on Monday 23rd February, and the third in the folder Astrophysics of Galaxies, is “MEGATRON: Disentangling Physical Processes and Observational Bias in the Multi-Phase ISM of High-Redshift Galaxies” by Nicholas Choustikov (U. Oxford, UK) and 12 others based in UK, USA, France, Korea and Belgium. The study uses MEGATRON simulations to analyze the interstellar medium (ISM) of high-redshift galaxies, finding it denser and less metal-enriched than local galaxies with implications for line ratios as diagnostics
The overlay is here:
The official version can be found on arXiv here and the Fediverse announcement is here:
New Publication at the Open Journal of Astrophysics: "MEGATRON: Disentangling Physical Processes and Observational Bias in the Multi-Phase ISM of High-Redshift Galaxies" by Nicholas Choustikov (U. Oxford, UK) and 12 others based in UK, USA, France, Korea and Belgium
New Publication at the Open Journal of Astrophysics: "Redshift Assessment Infrastructure Layers (RAIL): Rubin-era photometric redshift stress-testing and at-scale production" by the RAIL Team (31 authors) and the Dark Energy Science Collaboration
Moving on to Tuesday 24th February, the fifth paper this week, is “Feedback shaped the galaxy morphological sequence in presence of mergers” by Masafumi Noguchi (Tohoku University, Japan). This article was published in the folder Astrophysics of Galaxies. This study suggests that galaxy morphology, specifically the mass ratios of bulges and disks, is influenced by galaxy mergers and feedback processes from active galactic nuclei and supernovae.
The overlay is here:
The accepted version can be found on arXiv here, and the fediverse announcement is here:
New Publication at the Open Journal of Astrophysics: "Feedback shaped the galaxy morphological sequence in presence of mergers" by Masafumi Noguchi (Tohoku University, Japan)
The sixth paper this week is “HelioSpectrotron 5000: an interactive solar atlas” by Alexander G.M. Pietrow (AIP Potsdam, Germany). This was published on Tuesday 24th February in the folder Solar and Stellar Astrophysics. This describes HelioSpectrotron~5000 (HS5000), which is an interactive solar spectral atlas that allows comparison between high-resolution spectra and ground-based instrument observations, aiding in wavelength calibration and line identification. The software can be found here; I had a play with it yesterday and it’s very easy to use!
The overlay is here:
You can find the officially accepted version on arXiv here and the Mastodon announcement is here:
New Publication at the Open Journal of Astrophysics: "HelioSpectrotron 5000: an interactive solar atlas" by Alexander G.M. Pietrow (AIP Potsdam, Germany)
The seventh paper of this week was published on Thursday 26th February is “The Rise of Ionized Gas Filaments in Early-Type Galaxies” by Ryan Eskenasy (U. Kentucky, USA), Valeria Olivares (Universidad de Santiago de Chile) and Yuanyuan Su (U. Kentucky, USA). This article, in the folder Astrophysics of Galaxies, is an exploration of the formation of multiphase filamentary nebulae in early-type galaxies (ETGs), using VLT-MUSE IFU observations of 126 non-central ETGs, focussing on the hot gas components thereof.
The overlay is here:
The officially accepted version of this paper can be found on the arXiv here and the Mastodon announcement is here:
New Publication at the Open Journal of Astrophysics: "The Rise of Ionized Gas Filaments in Early-Type Galaxies" by Ryan Eskenasy (U. Kentucky, USA), Valeria Olivares (Universidad de Santiago de Chile) and Yuanyuan Su (U. Kentucky, USA)
New Publication at the Open Journal of Astrophysics: "Relationship Between Major Stellar Physical Parameters and Normal Mode Frequencies in Accreting White Dwarf Stars" by Praphull Kumar, Dean M. Townsley and Hunter Anz (U. Alabama, USA)
The ninth, and final, paper for this week is “A Semi-Supervised Learning Method for the Identification of Bad Exposures in Large Imaging Surveys” by Yufeng Luo (U. Wyoming, USA) and 8 others from the DESI Legacy Imaging Surveys Team. This was published on Friday 27th February, i.e yesterday, in the folder Instrumentation and Methods for Astrophysics. The paper describes a machine-learning approach for detecting poor-quality exposures in large astronomical imaging surveys, proving efficient and accurate in identifying problematic exposures.
The overlay is here:
The official version on arXiv can be found here and the Mastodon announcement follows:
New Publication at the Open Journal of Astrophysics: "A Semi-Supervised Learning Method for the Identification of Bad Exposures in Large Imaging Surveys" by Yufeng Luo (U. Wyoming, USA) and 8 others from the DESI Legacy Imaging Surveys Team
And that concludes this week’s update. We have now published 45 papers in two complete months of 2026, on which basis we can estimate about 270 papers in the year. For the record, in the first two months of 2025 we published 21 papers.
P.S. Thank you to the many people who responded to the latest call for editors. I’ve been sending out invitations and getting people onboard as quickly as I can, but I still have a number to get to so please bear with me!
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
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.
It may be a Bank Holiday weekend here in Ireland, but it’s still time for the usual Saturday update of the week’s new papers at the Open Journal of Astrophysics (although a bit later in the day than usual). Since the last update we have published another five papers, which brings the number in Volume 8 (2025) up to 161, and the total so far published by OJAp up to 396.
This week’s update is rather unusual because there are four papers in a series (or, more precisely, mathematically speaking, a sequence) all published on the same day (Wednesday October 22nd 2025), in the same folder (Cosmology and NonGalactic Astrophysics), with the same first author (Dhayaa Anbajagane of the University of Chicago), with long author lists and many co-authors in common. These papers all relate to the DECADE cosmic shear project. Instead of doing them one by one, therefore, I’ve decided to put all four overlays together and provide links to all the papers afterwards. As I’m trying to encourage people to follow our feed on the Fediverse via Mastodon (where I announce papers as they are published, including the all-important DOI), I’ll include links to each announcement there too.
New Publication at the Open Journal of Astrophysics: "The DECADE cosmic shear project I: A new weak lensing shape catalog of 107 million galaxies" by Dhayaa Anbajagane (University of Chicago, USA) et al. (54 authors)
New Publication at the Open Journal of Astrophysics: "The DECADE cosmic shear project II: photometric redshift calibration of the source galaxy sample" by Dhayaa Anbajagane (University of Chicago, USA) et al. (53 authors)
New Publication at the Open Journal of Astrophysics: "The DECADE cosmic shear project III: validation of analysis pipeline using spatially inhomogeneous data" by Dhayaa Anbajagane (University of Chicago, USA) et al. (53 authors)
New Publication at the Open Journal of Astrophysics: "The DECADE cosmic shear project IV: cosmological constraints from 107 million galaxies across 5,400 deg^2 of the sky" by Dhayaa Anbajagane (University of Chicago, USA) et al. (75 authors)
The fifth and final paper for this week is “Clustering of DESI galaxies split by thermal Sunyaev-Zeldovich effect” by Michael Rashkovetskyi of the Harvard-Smithsonian Center for Astrophysics, or CfA for short, and 48 others. This one was published on Wednesday 23rd October in the folder Cosmology and NonGalactic Astrophysics. This paper explores how the clustering properties of galaxies mapped by the Dark energy Spectroscopic Instrument (DESI) relate to the local thermal Sunyaev-Zeldovich emission mapped by the Atacama Cosmology Telescope (ACT). The overlay is here:
The officially accepted version can be found on arXiv here, and the fediverse announcement is here:
New Publication at the Open Journal of Astrophysics: "Clustering of DESI galaxies split by thermal Sunyaev-Zeldovich effect" by Michael Rashkovetskyi (Cfa Harvard-Smithsonian, USA) et al. (49 authors)
Yesterday evening (10pm Irish Time) saw the release of new results from the Dark Energy Spectroscopic Instrument (DESI), completing a trio of major announcements of cosmological results in the space of two days (the Atacama Cosmology Telescope and the Euclid Q1 release being the others). I didn’t see the DESI press conference but you can read the press release here.
There were no fewer than eight DESI papers on the astro-ph section of the arXiv this morning. Here are the titles with links:
You can see from the titles that the first seven of these relate to the second data release (DR2; three years of data) from DESI; the last one listed here is a description of the first data release (DR1), which is now publicly available.
Obviously there is a lot of information to digest in these papers so here are two members of the DESI collaboration talking with Shaun Hotchkiss on Cosmology Talks about the key messages from the analysis of Baryon Acoustic Oscillations (the BAO in the titles of the new papers):
A lot has been made in the press coverage of these results about the evidence that the standard cosmological model is incomplete; see, e.g., here. Here are a few comments.
As I see it, taken on their own, the DESI BAO results are broadly consistent with the ΛCDM model as specified by the parameters determined by the Cosmic Microwave Background (CMB) inferred from Planck. Issues do emerge, however, when these results are combined with other data sets. The most intriguing of these arises with the dark energy contribution. 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 of the dark energy ρ 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.
The DESI team allow (w0, wa) to act as free parameters and let the DESI data constrain them, either alone or in combinations with other data sets, finding evidence for departures from the “standard values”. Here’s an example plot:
The DESI data don’t include the standard point (at the intersection of the two dashed lines) but the discrepancy gets worse when other data (such as supernovae and CMB) are folded in, as in this picture. The weight of evidence suggests a dark energy contribution which is decreasing with time.
These results are certainly intriguing, and a lot of credit is due to the DESI collaboration for working so hard to identify and remove possible systematics in the analysis (see the papers above) but what do they tell us about ΛCDM?
My view is that we’ve never known what the dark energy actually is or why it is so large that it represents 70% of the overall energy density of the Universe. The Λ in ΛCDM is really just a place-holder, not there for any compelling physical reason but because it is the simplest way of accounting for the observations. In other words, it’s what it is because of Occam’s Razor and nothing more. As with any working hypothesis, the standard cosmological model will get updated whenever new information comes to light (as it is doing now) and/or if we get new physical insights into the origin of dark energy.
Do the latest observations cast doubt on the standard model? I’d say no. We’re seeing an evolutionary change from “We have no idea what the dark energy is but we think it might be a cosmological constant” to “We still have no idea what the dark energy is but we think it might not be a cosmological constant”.
Some weeks ago I posted an item about recent results that have emerged from the DESI (Dark Energy Spectroscopic Instrument) Collaboration. I have been a bit busy since then but I just saw that there is one of those Cosmology Talks about these results which I thought I would pass on. The contributors are Arnaud de Mattia, Hector Gil-Marín and Pauline Zarrouk and they are talking about the analsysis they have done using the “full shape” of the galaxy power spectrum. It’s quite a long video, but very illuminating.
The Mayall Telescope at Kitt Peak, in which DESI is housed. This PR image was taken during a meteor shower, which is not ideal observing conditions. Picture Credit: KPNO/NOIRLab/NSF/AURA/R. Sparks
I’ve just got time between meetings to mention that a clutch of brand new papers has emerged from the DESI (Dark Energy Spectroscopic Instrument) Collaboration. There is a press release discussing the results from the Lawrence Berkeley Laboratory here and one from the ICCUB in Barcelona here; several members of the group I visited there during sabbatical are working on DESI. Congratulations to them.
I haven’t had time to read them yet, but a quick skim suggests that the results are consistent with the standard cosmological model.
The latest batch contains three Key Publications:
DESI Collaboration et al., DESI 2024 II: Sample Definitions, Characteristics, and Two-point Clustering Statistics
Findlay et al. (2024), Exploring HOD-dependent systematics for the DESI 2024 Full-Shape galaxy clustering analysis
The links lead to the arXiv version of these papers. These articles can also be found, along with previously released publications by the DESI Collaboration, here.
Anyone who has read the latest papers is welcome to comment through the box below!
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In the Dark 