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Weekly Update from the Open Journal of Astrophysics – 25/10/2025

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , , , , , , , , , , , , , , , , , on October 25, 2025 by telescoper

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.

  1. “The DECADE cosmic shear project I: A new weak lensing shape catalog of 107 million galaxies“, accepted version on arXiv here.
  2. “The DECADE cosmic shear project II: photometric redshift calibration of the source galaxy sample“, accepted version on arXiv here.
  3. “The DECADE cosmic shear project III: validation of analysis pipeline using spatially inhomogeneous data“, accepted version on arXiv here.
  4. “The DECADE cosmic shear project IV: cosmological constraints from 107 million galaxies across 5,400 deg2 of the sky“, accepted version on arXiv here.

The fediverse announcements follow:

Open Journal of Astrophysics

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)

doi.org/10.33232/001c.146158

October 22, 2025, 12:42 pm 2 boosts 0 favorites

Open Journal of Astrophysics

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)

doi.org/10.33232/001c.146159

October 22, 2025, 1:07 pm 2 boosts 0 favorites

Open Journal of Astrophysics

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)

doi.org/10.33232/001c.146160

October 22, 2025, 1:57 pm 1 boosts 0 favorites

Open Journal of Astrophysics

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)

doi.org/10.33232/001c.146161

October 22, 2025, 2:47 pm 1 boosts 0 favorites

 

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:

Open Journal of Astrophysics

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)

doi.org/10.33232/001c.146033

October 23, 2025, 8:28 am 1 boosts 0 favorites

 

That concludes the papers for this week. With one week to go and our total at 396, I still think we might reach the 400 total by the end of October.

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Weekly Update from the Open Journal of Astrophysics – 27/09/2025

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , , , , , , , , , , , , , , , , , , , on September 27, 2025 by telescoper

It’s Saturday again, so it’s time for a summary of the week’s new papers at the Open Journal of Astrophysics. Since the last update we have published five new papers, which brings the number in Volume 8 (2025) up to 141, and the total so far published by OJAp up to 376.

The first paper to report this week is “The Bispectrum of Intrinsic Alignments: Theory Modelling and Forecasts for Stage IV Galaxy Surveys” by Thomas Bakx (Utrecht U., NL), Alexander Eggemeier (U. Bonn, DE), Toshiki Kurita (MPA Garching, DE), Nora Elisa Chisari (Leiden U., NL) and Zvonimir Vlah (Ruđer Bošković Institute, Croatia). This paper was published on Monday 22nd September 2025 in the folder Cosmology and NonGalactic Astrophysics. It studies the bispectrum of intrinsic galaxy alignments, a possible source of systematic errors in extracting cosmological information from the analysis of weak lensing surveys.

The overlay is here:

You can make this larger by clicking on it.  The officially accepted version of this paper can be found on the arXiv here.

The second paper this week, published on Tuesday 23rd September 2025 is “Reanalysis of Stage-III cosmic shear surveys: A comprehensive study of shear diagnostic tests” by Jazmine Jefferson (University of Chicago, USA) and 13 others for the LSST Dark Energy Science Collaboration. It is also in the folder Cosmology and NonGalactic Astrophysics; it describes diagnostic tests on three public shear catalogs (KiDS-1000, Year 3 DES-Y3 s, and Year 3 HSC-Y3); not all the surveys pass all the tests.

The corresponding overlay is here:

You can find the officially accepted version on arXiv here.

The third one this week, published on Wednesday 24th September 2025 in the folder Astrophysics of Galaxies, is “Is feedback-free star formation possible?” by Andrea Ferrara, Daniele Manzoni, and Evangelia Ntormousi (all of the Scuola Normale Superiore, Pisa, Italy). This paper presents an argument that Lyman-alpha radiation pressure strongly limits star formation efficiency, even at solar metallicities, so that a feedback-free star formation phase is not possible without feedback. The overlay is here:

You can find the officially-accepted version on arXiv here.

Next we have “Microphysical Regulation of Non-Ideal MHD in Weakly-Ionized Systems: Does the Hall Effect Matter?” by Philip F. Hopkins (Caltech, USA), Jonathan Squire (U. Otago, New Zeland), Raphael Skalidis (Caltech) and Nadine H. Soliman (Caltech). This was also published on Wednesday 24th September 2025, but in the folder Earth and Planetary Astrophysics. It presents an improved treatment of non-ideal effects in magnetohydrodynamics, particularly the Hall effect, and a discussion of the implications for weakly-ionized astrophysical systems.

The corresponding overlay is here:

 

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

The fifth, and last, one for this week is “The Local Volume Database: a library of the observed properties of nearby dwarf galaxies and star clusters” by Andrew B. Pace (University of Virginia, USA). This one was published on Friday 26th September (i.e. yesterday) in the folder Astrophysics of Galaxies. It presents a catalogue of positional, structural, kinematic, chemical, and dynamical parameters for dwarf galaxies and star clusters in the Local Volume. The overlay is here:

You can find the officially-accepted version of this paper on arxiv here.

 

And that concludes the report for this week. I’ll post another update next Saturday.

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Weekly Update from the Open Journal of Astrophysics – 13/09/2025

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , , , , , , , , , , , , , , , , , , , , , , , , on September 13, 2025 by telescoper

It’s Saturday again, so it’s time for another summary of the week’s new papers at the Open Journal of Astrophysics. Since the last update we have published seven new papers, which brings the number in Volume 8 (2025) up to 134, and the total so far published by OJAp up to 369. We seem to be emerging for the slight late-summer hiatus we have experienced over the last few weeks.

Anyway, the first paper to report this week is “Observing the Sun with the Atacama Large Aperture Submillimeter Telescope (AtLAST): Forecasting Full-disk Observations” by Mats Kirkaune & Sven Wedemeyer (U. Oslo, Norway), Joshiwa van Marrewijk (Leiden U., Netherlands), Tony Mroczkowski (ESO, Garching, Germany) and Thomas W. Morris (Yale, USA). This paper discusses possible strategies and parameters for full-disk observations of the Sun using the proposed Atacama Large Aperture Submillimeter Telescope (AtLAST). It was published on Tuesday 9th September 2025 in the folder Solar and Stellar Astrophysics.

The overlay is here:

 

You can make this larger by clicking on it.  The officially accepted version of this paper can be found on the arXiv here.

The second paper this week, published on Wednesday 10th September in the folder Cosmology and NonGalactic Astrophysics, is “The exact non-Gaussian weak lensing likelihood: A framework to calculate analytic likelihoods for correlation functions on masked Gaussian random fields” by Veronika Oehl and Tilman Tröster (ETH Zurich, Switzerland).  This paper shows how to calculate likelihoods for the correlation functions of spin-2 Gaussian random fields defined on the sphere in the presence of a mask with applications to weak gravitational lensing.

The overlay is here:

and you can find the final accepted version on arXiv here.

Next one up, the third paper this week, is  “Subspace Approximation to the Focused Transport Equation. II. The Modified Form” by B. Klippenstein and Andreas Shalchi (U. Manitoba, Canada). This was also published on 10th September 2025 in the folder Solar and Stellar Astrophysics. It is about solving the focused transport equation analytically and numerically using the subspace method in two or more dimensions.

You can find the final accepted version on arXiv here.

The fourth paper of this week was also published on Wednesday 10th September. It is “Mass models of galaxy clusters from a non-parametric weak-lensing reconstruction” by Tobias Mistele (Case Western Reserve U., USA), Federico Lelli (INAF, Firenze, Italy), Stacy McGaugh (Case Western), James Schombert (U. Oregon, USA) and Benoit Famaey (Université de Strasbourg, France).  Published in the folder Cosmology and NonGalactic Astrophysics, it presents new, non-parametric deprojection method for weak gravitational lensing applied to a sample of galaxy clusters. The overlay is here:

You can find the officially accepted version on arXiv here.

The fifth paper of the week is “A Swift Fix II: Physical Parameters of Type I Superluminous Supernovae” by Jason T. Hinkle & Benjamin J. Shappee (U. Hawaii, USA) and Michael A. Tucke (Ohio State, USA). This one was published on Thursday 11th September 2025 in the folder High-Energy Astrophysical Phenomena. The paper uses recalibrated Swift photometry to recompute peak luminosities and other properties of a sample of superluminous Type I supernovae. The overlay is here:

You can find the official accepted version on arXiv here.

Paper No. 6 for this week is “Detailed Microwave Continuum Spectra from Bright Protoplanetary Disks in Taurus” by Caleb Painter (Harvard, USA) and 11 others, too numerous to mention by name, based in the USA, Germany, Mexico and Taiwan.  This one was published in the folder marked Solar and Stellar Astrophysics on September 11th 2025. It presents new observations sampling the microwave (4-360 GHz) continuum spectra from eight young stellar systems in the Taurus region. The overlay is here:

 

The final version can be found on arXiv here.

The last paper for this update is “On Soft Clustering For Correlation Estimators” by Edward Berman (Northeastern University, USA) and 13 others based in the USA, France, Denmark and Finland and Cosmos-Web:The JWST Cosmic Origins Survey. This was published on Friday 12th September 2025 in the folder Instrumentation and Methods for Astrophysics. It presents an algorithm for estimating correlations that clusters objects in a probabilistic fashion, enabling the uncertainty caused by clustering to be quantified simply through model inference. The overlay is here:

You can find the final version on arXiv here.

And that’s all the papers for this week. I’ve noticed a significant recent increase in the number of papers in Solar and Stellar Astrophysics, which means we’re broadening our impact across the community. Which is nice.

P.S. I found out last week that, according to NASA/ADS, papers in OJAp have now accumulated over 5000 citations.

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The KiDS Legacy

Posted in The Universe and Stuff with tags , , , , , , , , on March 30, 2025 by telescoper

What with all the cosmological goings-on of the past couple of weeks – see here, here and here – I quite forgot to mention another important set of results. These are from the final data release Kilo-Degree Survey known as KiDS for short and represent a final analysis of the complete dataset. For those of you not in the know, KiDs is a weak lensing shear tomography survey and its core science drivers are to map the large scale matter distribution in the Universe and constrain the equation of state of Dark Energy. The results can be found in three papers on arXiv, which you can add to your reading list:

As far as I’m concerned, the main result to leap out from the cosmological analysis, which primarily constrains the clumpiness of matter in the universe, expressed by the density parameter Ωm and a fluctuation amplitude σ8 in the combined parameter “S8“, which is constrained almost independently from Ωm. The value obtained for this parameter by KiDS has previously been “in tension” with values from other experiments (notably Planck) ; see here for a discussion. The new results, however, seem consistent with the standard cosmological model. Here is a figure from the last paper in the above list that illustrates the point:

As is often the case, there’s also one of those nice Cosmology Talks videos that discusses this and other aspects of the KiDS Legacy results to which I refer you for more details!

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Weekly Update at the Open Journal of Astrophysics – 15/03/2025

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , , , , , , , , , , on March 15, 2025 by telescoper

The Ideas of March are come, so it’s time for another update of papers published at the Open Journal of Astrophysics. Since the last update we have published two papers, which brings the number in Volume 8 (2025) up to 27 and the total so far published by OJAp up to 262.

The first paper to report is “Dark Energy Survey Year 6 Results: Point-Spread Function Modeling” by Theo Schutt and 59 others distributed around the world, on behalf of the DES Collaboration. It was published on Wednesday March 12th 2025 in the folder Cosmology and NonGalactic Astrophysics. It discusses the improvements made in modelling the Point Spread Function (PSF) for weak lensing measurements in the latest Dark Energy Survey (6-year) data and prospects for the future.

Here is the overlay, which you can click on to make larger if you wish:

 

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

The other paper published this week is “Exploring Symbolic Regression and Genetic Algorithms for Astronomical Object Classification” by Fabio Ricardo Llorella (Universidad Internacional de la Rioja, Spain) & José Antonio Cebrian (Universidad Laboral de Córdoba, Spain), which came out on Thursday 13th March. This one is in the folder marked Astrophysics of Galaxies and it discusses the classification of astronomical objects in the Sloan Digital Sky Survey SDSS-17 dataset using a combination of Symbolic Regressiion and Genetic Algorithms.

The overlay can be seen here:

You can find the “final” version on arXiv here.

That’s it for this week. I’ll have more papers to report next Saturday.

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Weekly Update from the Open Journal of Astrophysics – 01/02/2025

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , , , , , , , , , , , , , , , on February 1, 2025 by telescoper

It’s Saturday morning, so once again it’s time for an update of papers published at the Open Journal of Astrophysics. There were no papers to report last week but since the last update we have published four new papers, which brings the number in Volume 8 (2025) up to 11 and the total so far published by OJAp up to 246.

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

First one up is  “A halo model approach for mock catalogs of time-variable strong gravitational lenses” by Katsuya T. Abe & Masamune Oguri (Chiba U, Japan), Simon Birrer & Narayan Khadka (Stony Brook, USA), Philip J. Marshall (Stanford, USA), Cameron Lemon (Stockholm U., Sweden), Anupreeta More (IUCAA, India), and the LSST Dark Energy Science Collaboration. It was published on 27th January 2025 in the folder marked Cosmology and NonGalactic Astrophysics. The paper discusses how to generate mock catalogs of strongly lensed QSOs and Supernovae on galaxy-, group-, and cluster-scales based on a halo model that incorporates dark matter halos, galaxies, and subhalos.

 

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

This paper, also published on Monday 27th January 2025, but in the folder Astrophysics of Galaxies, is “The Soltan argument at redshift 6: UV-luminous quasars contribute less than 10% to early black hole mass growth” by Knud Jahnke (MPI Heidelberg, Germany). This paper presents an argument that almost all growth of supermassive black hole mass at z>6 does not take place in UV-luminous quasars.

Here is a screen grab of the overlay, which includes the abstract:You can find the officially accepted version of the paper on the arXiv here.

The third paper to announce, published on 29th January 2025 in the folder Cosmology and NonGalactic Astrophysics, is “A Heavy Seed Black Hole Mass Function at High Redshift – Prospects for LISA” by Joe McCaffrey & John Regan (Maynooth U., Ireland), Britton Smith (Edinburgh U., UK), John Wise (Georgia Institute of Technology, USA), Brian O’Shea (Michigan State U., USA) and Michael Norman (University of California, San Diego). This is a numerical study of the growth rates of massive black holes in the early Universe and implications for their detection via gravitational wave emission.

You can see the overlay here:

 

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

The last paper of this batch is “Forecasting the Detection of Lyman-alpha Forest Weak Lensing from the Dark Energy Spectroscopic Instrument and Other Future Surveys” by Patrick Shaw & Rupert A. C. Croft (Carnegie Mellon U., USA) and R. Benton Metcalf (U. Bologna, Italy). This paper, published on January 30th 2025, is about extending the applicationof  Lyman-α forest weak gravitational lensing to lower angular source densities than has previously been done, with forecasts for future spectral surveys. It is in the folder marked Cosmology and NonGalactic Astrophysics.

The overlay is here

 

You can find the accepted version on arXiv here.

Incidentally, we currently have 121 papers under review, including 81 under a revise and resubmit request.

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

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Three New Publications at the Open Journal of Astrophysics

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , , , , , , , , on November 2, 2024 by telescoper

It’s Saturday, so it’s time once again for another summary of business at the  Open Journal of Astrophysics. This week I have three papers to announce, which brings the total we have published so far this year (Vol. 7) to 98 and the total published by OJAp to 213.

First one up, published on Tuesday 29th October 2024, is “Cosmology with shear ratios: a joint study of weak lensing and spectroscopic redshift datasets” by Ni Emas & Chris Blake (Swinburne U., Australia), Rossana Ruggeri (Queensland U, Australia) and Anna Porredon (Ruhr University, Bochum, Germany). This paper is in the folder marked Cosmology and NonGalactic Astrophysics. The paper investigates the use of shear ratios as a cosmological diagnostic, with applications to lensing surveys

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

You can read the paper directly on arXiv here.

The second paper to present, also published on Tuesday 29th October 2024, is “Echo Location: Distances to Galactic Supernovae From ASAS-SN Light Echoes and 3D Dust Maps” by Kyle D. Neumann (Penn State), Michael A. Tucker & Christopher S. Kochanek (Ohio State), Benjamin J. Shappee (U. Hawaii), and K. Z. Stanek (Ohio State), all based in the USA. This paper is in the folder marked High-Energy Astrophysical Phenomena and it presents a new approach to estimating the distance to a source by combining light echoes with recent three-dimensional dust maps with application to supernova distances.

The overlay looks like this:

 

 

You can read this paper directly on the arXiv here.

Last, but by no means least, comes  “A deconstruction of methods to derive one-point lensing statistics” by Viviane Alfradique (Universidade Federal do Rio De Janeiro, Brazil), Tiago Castro (INAF Trieste, Italy), Valerio Marra (Trieste), Miguel Quartin (Rio de Janeiro), Carlo Giocoli (INAF Bologna, Italy), and Pierluigi Monaco (Trieste).  Published in the folder marked Cosmology and NonGalactic Astrophysics, it describes a comparative study of different methods of approximating the one-point probability density function (PDF) for use in the statistical analysis of gravitational lensing.

Here is a screengrab of the overlay:

 

To read the accepted version of this on the arXiv please go here.

That’s it for this week. I hope to post another update next weekend, by when we might well have reached a century for this year!

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Six New Publications at the Open Journal of Astrophysics

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , , , , , , , , , , , , , , , on October 19, 2024 by telescoper

It’s Saturday morning again and time to post an update of activity at the Open Journal of Astrophysics. As last week there are six papers to announce, bringing the count in Volume 7 (2024) up to 93 and the total altogether up to 208.

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

First one up, published on Monday 14th October 2024, is in the folder marked Cosmology and NonGalactic Astrophysics and is called “Backreaction in Numerical Relativity: Averaging on Newtonian gauge-like hypersurfaces in Einstein Toolkit cosmological simulations“. This paper presents a numerical study of the effect of local inhomogeneities on the dynamical evolution of the Universe, i.e. the so-called “backreaction” problem; the authors are Alexander Oestreicher and Sofie Marie Koksbang of the University of Southern Denmark, Odense, Denmark.

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

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

The second paper to announce, published on 15th October 2024, is “Weak-Lensing Shear-Selected Galaxy Clusters from the Hyper Suprime-Cam Subaru Strategic Program: II. Cosmological Constraints from the Cluster Abundance” by I-Non Chiu (National Cheng Kung University, Taiwan) and 11 others based in Taiwan, Japan, India and the USA. This paper, which is also in the folder Cosmology and NonGalactic Astrophysics  presents constraints on cosmological parameters obtained from a sample of galaxy clusters

You can see the overlay here:

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

The third paper is “Image formation near hyperbolic umbilic in strong gravitational lensing” by Ashish Kumar Meena (Ben Gurion University, Israel) and Jasjeet Singh Bagla (IISER Mohali, India). It presents a detailed theoretical discussion of a particular form of strong gravitational lensing and its observational consequences; it is in the folder Astrophysics of Galaxies and was published on October 15th 2024.

The overlay is here:

 

The officially accepted version can be found on arXiv here.

The fourth paper, published on 16th October 2024 and in the folder Astrophysics of Galaxies,  is “Weak Gravitational Lensing around Low Surface Brightness Galaxies in the DES Year 3 Data” by N. Chicoine (University of Chicago, USA) et al. (105 authors; DES Collaboration). It presents a  demonstration of the viability of using weak gravitational lensing to constrain the halo masses of low surface brightness galaxies.

The overlay is here

 

You can find the officially accepted version of this paper here.

The fifth paper in this batch is “Imprints of interaction processes in the globular cluster system of NGC 3640” by Ana I Ennis (Waterloo, Canada) and Juan Pablo Caso & Lilia Patricia Bassino (Instituto de Astrofísica de La Plata, Argentina). This one was also published on 16th October 2024 and is in the folder Astrophysics of Galaxies, Here is the overlay

 

 

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

Finally for this week we have “On the nature of the C IV-bearing circumgalactic medium at 𝒛∼𝟏” by Suyash Kumar, Hsiao-Wen Chen, Zhijie Qu & Mandy C. Chen (U. Chicago), Fakhri S. Zahedy (U. North Texas), Sean D. Johnson (Carnegie Observatories), Sowgat Muzahid (IUCAA, India) and Sebastiano Cantalupo (U. Milan Bicocca)

The overlay is here

 

You can find the officially-accepted version on arXiv here.

That’s it for now. More next week!

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What is Weak Gravitational Lensing?

Posted in Euclid, The Universe and Stuff with tags , , , , , , on September 15, 2024 by telescoper

I haven’t posted anything about the European Space Agency’s Euclid mission recently but I can remedy that today by sharing a new video that describes one of the methods that Euclid will use to map the dark Universe. Here’s the video:

Here are the credits

Credit: ESA/Euclid Consortium/Cacao Cinema

License: ESA Standard Licence

And here’s the explainer that goes with it:

ESA’s Euclid mission is surveying the sky to explore the composition and evolution of the dark Universe. But how can Euclid see the invisible? Watch this video to learn about the light-bending effect that enables scientists to trace how dark matter is distributed in the Universe.

By making use of Euclid’s flagship simulation, the video illustrates how dark-matter filaments subtly alter the shape of galaxies. Light travelling to us from vastly distant galaxies is bent and distorted by concentrations of matter along its way. The effect is called gravitational lensing because matter (both ‘normal’ and dark matter) acts as a kind of magnifying glass.

Scientists distinguish between strong and weak gravitational lensing. In strong gravitational lensing distortions of background galaxies or other light sources are very apparent, resulting in arcs, multiple images or so-called Einstein rings. In weak lensing, background sources appear only mildly stretched or displaced. This means we can only detect this effect by analysing large numbers of sources in a statistical way.

The further we look, the more prominent the distortions from weak gravitational lensing are, because there are more dark-matter structures acting as lenses between us and the light sources.

Euclid will measure the distorted shapes of billions of galaxies over 10 billion years of cosmic history, providing a 3D view of the dark matter distribution in our Universe. This will shed light on the nature of this mysterious component.

The map of the distribution of galaxies over cosmic time will also teach us about dark energy, which affects how quickly the Universe expands. By charting the Universe’s large-scale structure in unprecedented detail, Euclid will enable scientists to trace how the expansion has changed over time.

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Four New Publications at the Open Journal of Astrophysics

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , , , on July 20, 2024 by telescoper

This week we have published four papers at the Open Journal of Astrophysics, which I now present to you here. These four take the count in Volume 7 (2024) up to 60 and the total published altogether by OJAp up to 175. It is gratifying to see the range of high-quality papers published steadily increasing. We are getting several papers submitted every day now.

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

First one up is: “A population of neutron star candidates in wide orbits from Gaia astrometry” by Kareem El-Badry (Caltech, USA) and 12 others based across the world.  The paper presents  a spectroscopic study of neutron star candidates identified using GAIA astrometry to be in wide binary orbits around main sequence stars,  was published on 15th July 2024 and is in the folder marked Solar and Stellar Astrophysics. For more information about this one, see here.

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

 

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

The second paper to announce is “Systematic Effects in Galaxy-Galaxy Lensing with DESI” and was written by Johannes Ulf Lange (University of Michigan, Ann Arbor, USA) and 58 others, again distributed internationally.  This one reports a study of systematic effects (such as incompleteness and intrinsic alignment) on galaxy-galaxy lensing results from the Dark Energy Spectroscopic Instrument (DESI) survey. This one is in the folder called Cosmology and NonGalactic Astrophysics and was published on 16th July 2024.

You can see the overlay here:

 

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

The next paper is also in the folder called Cosmology and NonGalactic Astrophysics.  It is entitled “Unleashing cosmic shear information with the tomographic weak lensing PDF” and is by by Lina Castiblanco (Newcastle Univresity, UK), Cora Uhlemann (Bielefeld University, Germany), Joachim Harnois-Déraps (Newcastle University, UK) and Alexandre Barthelemy (Ludwig-Maximilians-Universität, Germany). This one was published on 17th July 2024.

Here is the overlay:

 

You can find the full text for this one on the arXiv here.

Last but by no means least, published on 18th July 2024, we have a paper  entitled “When to interfere with dark matter? The impact of wave dynamics on statistics“. The primary classification for this one is again Cosmology and Nongalactic Astrophysics and it discusses the imprint of wave-mechanical behaviour, perhaps associated with ultra-light scalar field dark matter on the statistical properties of large-scale structure. The authors are Alex Gough (Newcastle University, UK) and Cora Uhlemann (Bielefeld University, Germany; who also featured in the author list of the previous paper). This is a paper close to my own interests, but because I know both authors well and was the PhD examiner of the first author I thought it best to recuse myself from an editorial role on this one.

 

You can click on the image of the overlay to make it larger should you wish to do so. You can find the officially accepted version of the paper on the arXiv here.

It did look likely at one stage that we might publish a paper every day last week, but the final version of one other paper didn’t make it onto arXiv in time to be announced on Friday so I will publish that one on Monday.

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