Euclid Space Warps – help the hunt for galaxy-galaxy lenses!

A collage of fourteen by eight squares containing examples of gravitational lenses. Credit: ESA/Euclid/Euclid Consortium/NASA, image processing by M. Walmsley, M. Huertas-Company, J.-C. Cuillandre.

I’m sharing the text of a press release from Euclid here to encourage readers to join in this new Zooniverse project.

–o–

In brief

With the launch of Space Warps, a new citizen science project on the Zooniverse platform, you can now join in the search to find rare and elusive strong gravitational lenses in never-before-seen images captured by the European Space Agency’s Euclid space telescope. The project aims at shining a light on dark matter in galaxies and providing clues about mysterious dark energy.

In-depth

Warps in spacetime do not only show up in science fiction movies like Interstellar. In real life, we can see the warping effect that gravity has on spacetime in the form of gravitational lensing.

The enormous gravity of a massive object – such as a galaxy or cluster of galaxies – distorts the shape of spacetime and can bend the light rays coming from a distant galaxy behind. By warping spacetime, the foreground galaxy acts like a magnifying glass.

Light from the background object that would be obscured doesn’t travel in a straight line anymore. Instead, it curves around the intervening mass, often producing multiple images, stretched arcs, or even a complete ring known as ‘Einstein ring’, like the one recently discovered by Euclid.

Strong gravitational lenses offer a striking demonstration of Einstein’s theory of general relativity, showing that matter in the Universe can act as a natural telescope, bringing distant objects into sight.

ESA’s Euclid telescope is revolutionising the studies of strong gravitational lensing by providing very sensitive imaging over large swaths of the sky in unprecedented detail. This is exactly what is needed to identify rare gravitational lenses.

In March 2025, 500 galaxy-galaxy strong lenses were found nestled in just the first 0.04% of Euclid data, most of them previously unknown. This pioneering catalogue was created thanks to the combined effort from citizen scientists, artificial intelligence (AI) and researchers.

Early glimpse of new Euclid images

As Euclid continues its survey, sending around 100 GB of data back to Earth every day, ESA and the Euclid Consortium once again need help from citizen scientists to identify strong gravitational lenses in a large data set.

For this, the Space Warps team has launched a citizen science project based on new Euclid images, which will be part of the future Euclid Data Release 1. While this data is not public yet, by participating in this new citizen science project you can get an early glimpse of these new images of galaxies captured by the telescope.

For this project, you will be inspecting new high quality imaging data from Euclid in which many previously unknown strong lenses are hiding. About three hundred thousand images pre-selected by AI algorithms will be shown, which are fine-tuned with the results from the initial citizen-science Euclid strong lens search. These are the highest ranked candidates from a whopping 72 million galaxies from DR1 that were classified by the AI algorithms. Scientists expect that this exquisite high-quality data will reveal more than 10 000 new lenses.

What can we learn from strong lenses

The Euclid mission explores how the Universe has expanded and how its structure has changed through cosmic history using mainly two methods: weak lensing and baryonic acoustic oscillations. From this, scientists can learn more about the role of gravity and the nature of dark matter and dark energy.

Strong gravitational lenses can also provide insights into these central questions. For example, strong lensing features can ‘weigh’ individual galaxies and clusters of galaxies. This reveals the total matter (whether dark or light) and traces the distribution of dark matter. By studying strong lenses across cosmic time, scientists can trace the expansion of the Universe and its apparent acceleration. This will provide additional insight into the role of dark energy.

“We’ve already seen the success of combining AI with visual inspection by citizen volunteers and scientists on Space Warps, efficiently finding hundreds of high‑probability lens candidates in an initial small Euclid search in 2024”, explains Aprajita Verma, Space Warps’ co-founder and project lead at the University of Oxford, UK.
“In this brand new DR1 data, 30 times larger than the initial search and together with our improved AI algorithms, we are expecting to find more than 10 000 high quality lens candidates. This is more than four times the number of lenses than we have been able to find since the first gravitational lens was discovered nearly 50 years ago.”

This step-change is possible thanks to Euclid. The mission can map large areas of the sky with unique sharpness, an ideal combination for finding rare objects like strong gravitational lenses.

“We can’t wait to see what we will find within this unprecedented dataset. Join us on Space Warps to take part in this exciting search!” concludes Aprajita.

About Euclid
Euclid was launched in July 2023 and started its routine science observations on 14 February 2024. The goal of the mission is to reveal the hidden influence of dark matter and dark energy on the visible Universe. Over a period of six years, Euclid will observe the shapes, distances and motions of billions of galaxies out to 10 billion light-years.

Euclid is a European mission, built and operated by ESA, with contributions from NASA. The Euclid Consortium – consisting of more than 2000 scientist from 300 institutes in 15 European countries, the USA, Canada, and Japan – is responsible for providing the scientific instruments and scientific data analysis. ESA selected Thales Alenia Space as prime contractor for the construction of the satellite and its service module, with Airbus Defence and Space chosen to develop the payload module, including the telescope. NASA provided the detectors of the Near-Infrared Spectrometer and Photometer, NISP. Euclid is a medium-class mission in ESA’s Cosmic Vision Programme.

#Euclid #EuclidConsortium #strongGravitationalLensing #Zooniverse

Weekly Update from the Open Journal of Astrophysics – 18/04/2026

It is Saturday morning, and therefore time for yet 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 82 and the total so far published by OJAp up to 530.

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 “Beyond Spherical geometry: Unraveling complex features of objects orbiting around stars from its transit light curve using deep learning” by Ushasi Bhowmick & Shivam Kumaran (Indian Space Research Institute, Ahmedabad, India). This study uses deep neural networks to predict the shape of objects orbiting stars based on their transit light curves, demonstrating the potential to extract geometric information from these systems. It was published on Monday 13th April in the folder Earth and Planetary Astrophysics and the overlay can be seen here:

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

https://fediscience.org/@OJ_Astro/116395992732332356

The second paper for this week, also published on Monday 13th April but in the folder Astrophysics of Galaxies, is “statmorph-lsst: Quantifying and correcting morphological biases in galaxy surveys” by Elizaveta Sazonova (U. Waterloo, Canada) and an international cast of 18 others. This paper presents an investigation of potential biases in quantitative morphology metrics used in galaxy evolution studies, proposing two new measurements to resolve biases, and provides a related Python package (statmorph-lsst), which can be found here on github.

The overlay for this one is here:

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

https://fediscience.org/@OJ_Astro/116396069424189312

Next one up, the third paper of the week, one of four published on Friday 17th April, is “Disentangling the galactic and intergalactic components in 313 observed Lyman-alpha line profiles between redshift 0 and 5” by Siddhartha Gurung-López (Universitat de València, Spain) and 7 others based in Spain and Germany. Published in the folder Astrophysics of Galaxies, this paper uses the zELDA package to analyze Lyman-alpha photons from star-forming galaxies, revealing IGM effects dominate Lyman-alpha observability at high redshifts, while galactic outflows become more important at lower z.

The overlay for this one is here:

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

https://fediscience.org/@OJ_Astro/116418831864134501

The fourth paper this week, also published on Friday 17th April is “Using Symbolic Regression to Emulate the Radial Fourier Transform of the Sérsic Profile for Fast, Accurate and Differentiable Galaxy Profile Fitting” by Tim B. Miller (Northwestern University, USA) and Imad Pasha (Yale University, USA). This one is published in the folder Instrumentation and Methods for Astrophysics: it develops an emulator for galaxy profile fitting in Fourier space, improving speed by 2.5 times with minimal accuracy loss, aiding in managing increasing data flow.

The overlay is here:

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

https://fediscience.org/@OJ_Astro/116418855010158656

The fifth paper for this week is “The THESAN project: Lyman-alpha emitters as probes of ionized bubble sizes” by Meredith Neyer (MIT, USA) and 6 others based in the USA, Colombia, Canada, Japan and UK. The study uses THESAN simulations to explore how Lyman-alpha emitters (LAEs) trace ionized bubble sizes during the Epoch of Reionization, providing a framework for interpreting LAE surveys. This was published on Friday 17th April in the folder Astrophysics of Galaxies.

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:

https://fediscience.org/@OJ_Astro/116418887225003954

The sixth and final paper for this week is “Closed-Form Statistical Relations Between Projected Separation, Semimajor Axis, Companion Mass, and Host Acceleration” by Timothy D Brandt (Space Telescope Science Institute, USA). This was published on Friday 17th April in the folder Solar and Stellar Astrophysics. In this paper the author derives statistical relationships between radial velocity, a companion’s mass, and projected separation, useful for calculations requiring derivatives. The results are verified with empirical comparisons to existing literature.

The overlay for this one is here:

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

https://fediscience.org/@OJ_Astro/116418938017199814

And that concludes this week’s update. I’ll do another one at the end of next week.

P.S. Just a reminder, for those of you into LinkedIn, that we now have a page there.

#arXiv250303824v4 #arXiv250820266v2 #arXiv250914875v2 #arXiv251018946v2 #arXiv251109644v2 #arXiv260114688v2 #AstrophysicsOfGalaxies #binaryStars #ComputationalAstrophysics #CosmologyAndNonGalacticAstrophysics #DiamondOpenAccess #DiamondOpenAccessPublishing #EarthAndPlanetaryAstrophysics #EpochOfReionization #galaxyFormation #GalaxyMorphology #galaxyProfiles #InstrumentationAndMethodsForAstrophysics #IntergalacticMedium #Ionization #LAEs #lightCurves #LSST #LymanAlphaEmitters #OpenAccess #OpenAccessPublishing #Orbits #SérsicProfile #SolarAndStellarAstrophysics #statmorphLsst #stellarHalos #strongGravitationalLensing #THESAN #zELDA

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

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

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

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

The overlay is here:

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

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

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

The overlay for this one is here:

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

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

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

The overlay for this one is here:

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

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

The overlay is here:

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

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

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

The overlay for this one is here:

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

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

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

P.S. For those of you into LinkedIn, we now have a page there.

#accretion #accretionDisks #arXiv250606921v2 #arXiv250820173v2 #arXiv251205194v2 #arXiv251208490v2 #arXiv260118954v2 #AstronomyEducation #AstrophysicsOfGalaxies #ComputationalAstrophysics #CosmologyAndNonGalacticAstrophysics #DiamondOpenAccess #DiamondOpenAccessPublishing #EulerianMethods #galaxyClusters #galaxyFormation #GHZ2 #haloModels #HighEnergyAstrophysicalPhenomena #InstrumentationAndMethodsForAstrophysics #InterstellarMedium #ionisation #jellyfishGalaxies #LagrangianMethods #LargeLanguageModels #MACSJ013802155 #OpenAccess #OpenAccessPublishing #stellarHalos #strongGravitationalLensing
New in the #VirtualObservatory: “XAO Pulsar Data Query” by Zhang Hailong, Yuan Jianping
http://data.xao.ac.cn/pulsar/pulsar/q/info
#Pulsar #StrongGravitationalLensing #Timing
Information on Service 'XAO Pulsar Data Query'

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

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.

#arXiv230903270v3 #arXiv240708718v2 #arXiv250406174v3 #arXiv250513145v2 #arXiv250613716v2 #arXiv250711801v2 #arXiv250721268v2 #AtacamaLargeApertureSubmillimeterTelescope #AtLAST #CorrelationFunctions #CosmologyAndNonGalacticAstrophysics #DiamondOpenAccess #FocusedTransportEquation #galaxyClusters #InstrumentationAndMethodsForAstrophysics #MicrowaveSpectroscopy #OpenJournalOfAstrophysics #ProtoplanetaryDisk #protoplanetaryDisks #SolarAndStellarAstrophysics #solarObservations #Spin2Fields #StatisticalMethods #strongGravitationalLensing #SuperluminousSupernovae #SWIFT #TheOpenJournalOfAstrophysics #weakGravitationalLensing

Weekly Update from the Open Journal of Astrophysics – 12/07/2025

It’s Saturday morning again, so it’s time again for an update of papers published 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 92, and the total so far published by OJAp  up to 327.

This was a slightly strange week, starting with the fact that there were no new arXiv announcements on Monday 7th July because of the 4th July holiday in the USA on Friday so no papers were published that day. We were not able to publish any papers on Wednesday 9th July either because Crossref was offline for 24 hours that day while its data was migrated into the cloud. Our publishing process requires a live connection with Crossref to deposit metadata upon publication so we can’t publish while that service is down. Fortunately the update seems to have gone well and normal services resumed the following day. That partially accounts for the fact that four of this week’s papers were published on 10th July.

Anyway, The 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.

The first paper to report is “The Jackknife method as a new approach to validate strong lens mass models” by Shun Nishida & Masamune Oguri (Chiba University, Japan) , Yoshinobu Fudamoto (Steward Observatory, USA) and Ayari Kitamura (Tohoku University, Japan). This article, which is in the folder marked Cosmology and NonGalactic Astrophysics,  describes and application of the Jackknife statistical resampling techique to gravitational lensing by removing lensed images and recalcualting the mass modelIt was published on Tuesday 8th July 2025. The overlay is here:

 

The officially-accepted version can be found on arXiv here.

The second paper is “Low redshift post-starburst galaxies host abundant HI reservoirs” by Sara Ellison (U. Victoria, Canada) and 10 others based in China, UK, Spain, USA and Canada.  This one was also published oon Tuesday 8th July but in the folder Astrophysics of Galaxies. This paper uses 21cm observations of a sample of post-starburst galaxies, to show  that they contain large reservoirs of neutral hydrogen. Here is the overlay:

You can find the final version of the manuscript on arXiv here.

Next one up, one of four published on Thursday 10th July, is “Predicting the number density of heavy seed massive black holes due to an intense Lyman-Werner field” by Hannah O’Brennan (Maynooth University, Ireland) and 7 others based in Ireland, USA and Italy. This paper presents an exploration of the scenario for black hole formation driven by Lyman-Werner photons (i.e. ultraviolet radiation in the range 11.2 to 13.6 eV). It is in the folder marked Cosmology and NonGalactic Astrophysics, and the overlay is here:

 

You can read the final accepted version on arXiv here.

The fourth paper this week, and the second published on 10th July, is “Chemical Abundances in the Metal-Poor Globular Cluster ESO 280-SC06: A Formerly Massive, Tidally Disrupted Globular Cluster” by Sam A. Usman (U. Chicago, USA) and 8 others based in the USA, Canada and Australia. This paper, which is in the folder Astrophysics of Galaxies, presents a detailed spectroscopic study of the chemical abundances in a Milky Way globular cluster ESO 280-SC06. The overlay is here:

The officially accepted version of the paper can be read here.

Next one up, also published on 10th July and also in the folder marked Astrophysics of Galaxies is “Predictions for the Detectability of Milky Way Satellite Galaxies and Outer-Halo Star Clusters with the Vera C. Rubin Observatory” by Kabelo Tsiane (U. Michigan) and 9 others on behalf of the LSST Dark Energy Science Collaboration.

The overlay is here:

 

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

The penultimate paper for this week, and the last of the batch published on 10th July,  is “Systematically Measuring Ultra-Diffuse Galaxies. VIII. Misfits, Miscasts, and Miscreants” by Dennis Zaritsky, Richard Donnerstein, and Donghyeon J. Khim (Steward Observatory, U. Arizona, USA). This paper presents a morphological study of weird and wonderful galaxies as part of an effort to Systematically Measure Ultra-Diffuse Galaxies (the SMUDGes survey). It is in the folder marked Astrophysics of Galaxies. The overlay is here:

 

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

The last article published this week is “Differential virial analysis: a new technique to determine the dynamical state of molecular clouds” by Mark R. Krumholz (ANU, Australia), Charles J. Lada (Harvard, USA) & Jan Forbrich (U. Herts, UK). This paper presents simple analytic models of supported and collapsing molecular clouds, tested using full 3D simulations and applied to observed clouds in Andromeda. It is in the folder marked Astrophysics of Galaxies and was published yesterday, i.e on Friday 11th July 2025. Here is the overlay

 

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

And that’s all the papers for this week. I will, however, take this opportunity to mention that a while ago I was interviewed about the Open Journal of Astrophysics by Colin Stuart on behalf of the Foundational Questions Institute; the write-up of the interview can be found here.

#arXiv250116474v2 #arXiv250200574v2 #arXiv250303066v2 #arXiv250416203v2 #arXiv250500553v2 #arXiv250524755v2 #arXiv250615664v2 #AstrophysicsOfGalaxies #blackHoles #chemicalAbundances #CosmologyAndNonGalacticAstrophysics #DiamondOpenAccess #DiamondOpenAccessPublishing #differentialVirialAnalysis #globularCluster #JackknifeResampling #LymanWernerRadiation #massiveBlackHoles #MilkyWay #OpenJournalOfAstrophysics #SMUDgesSurvey #StatelliteGalaxies #strongGravitationalLensing #TheOpenJournalOfAstrophysics #ultraDiffuseGalaxies #VeraCRubinObservatory

Weekly Update from the Open Journal of Astrophysics – 12/04/2025

Time for the weekly Saturday morning update of papers published at the Open Journal of Astrophysics. Since the last update we have published four new papers, which brings the number in Volume 8 (2025) up to 37 and the total so far published by OJAp up to 272.

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.

The first paper to report is “Searching for new physics using high precision absorption spectroscopy; continuum placement uncertainties and the fine structure constant in strong gravity” by Chung-Chi Lee (Big Questions Institute (BQI), Sydney, Australia), John K. Webb (Cambridge, UK), Darren Dougan (BQI), Vladimir A. Dzuba & Victor V. Flambaum (UNSW, Australia) and Dinko Milaković (Trieste, Italy).

This presents a discussion of the problem of continuum placement in high-resolution spectroscopy, which impacts significantly on fine structure constant measurements, and a method for mitigating its effects. The paper is in the folder Solar and Stellar Astrophysics and was published on Tuesday 8th April 2025. The overlay is here:

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

The second paper to announce, also published on 8th April 2025,  is “Deciphering Spatially Resolved Lyman-Alpha Profiles in Reionization Analogs: The Sunburst Arc at Cosmic Noon” by Erik Solhaug (Chicago, USA), Hsiao-Wen Chen (Chicago), Mandy C. Chen (Chicago),  Fakhri Zahedy (University of North Texas),  Max Gronke (MPA Garching, Germany),  Magdalena J. Hamel-Bravo (Swinburne, Australia), Matthew B. Bayliss (U. Cincinatti), Michael D. Gladders  (Chicago), Sebastián López (Universidad de Chile), Nicolás Tejos (Universidad Católica de Valparaíso, Chile).

This paper, which presents a study of the Lyman-alpha emission properties of a gravitationally-lensed galaxy at redshift z=2.37, appears in the folder Astrophysics of Galaxies. It was published

 

 

 

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

The third paper of the week  is “On the progenitor of the type Ia supernova remnant 0509-67.5” by Noam Soker (Technion, Haifa, Israel). This one was published on Wednesday 9th April 2025 in the folder High-Energy Astrophysical Phenomena. The author discusses possible ideas for the origin of a supernova that exploded inside a planetary nebula.

Here is the overlay:

 

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

Last (but certainly) not least for this week, published on April 11th 2025, we have “Are Models of Strong Gravitational Lensing by Clusters Converging or Diverging?” by Derek Perera (U. Minnesota), John H Miller Jr & Liliya L. R. Williams (U. Minnesota, USA), Jori Liesenborgs (Hasselt U., Belgium), Allison Keen (U. Minnesota), Sung Kei Li (Hong Kong University), Marceau Limousin (Aix Marseille Univ., France).  This papers study various models of a strong gravitational lensing system, the results suggesting that lens models are neither converging to nor diverging from a common solution for this system, regardless of method.

Here is the overlay:

 

 

The official published version can be found on the arXiv here.

 

That’s all the papers for this week. By way of a postscript I’ll just mention that the gremlins that have affected submissions to Crossref (which we rely on for registering the article metadata) have now been resolved and normal services have been restored.

#arXiv240910604v5 #arXiv241001849v2 #arXiv241105083v2 #arXiv250304709v2 #AstrophysicsOfGalaxies #CosmicNoon #DiamondOpenAccess #DiamondOpenAccessPublishing #fineStructureConstant #HighEnergyAstrophysicalPhenomena #HighResolutionSpectroscopy #PlanetaryNebula #reionization #SolarAndStellarAstrophysics #strongGravitationalLensing #SupernovaRemnant #TheOpenJournalOfAstrophysics

The Open Journal of Astrophysics

The Open Journal of Astrophysics is an arXiv overlay journal providing open access to peer-reviewed research in astrophysics and cosmology.

Another interesting strong lensing discovery by @NASAWebb : https://arxiv.org/abs/2504.03571
"if a bottom-heavy IMF for elliptical gals is employed, stellar mass estimations increase and can account for the majority of the lensing mass (up to ∼83\%), reducing the need for dark matter"!

#DarkMatter #Cosmology #StrongGravitationalLensing #JWST

JWSTs PEARLS: NIRCam imaging and NIRISS spectroscopy of a $z=3.6$ star-forming galaxy lensed into a near-Einstein Ring by a $z=1.258$ massive elliptical galaxy

We present the discovery, and initial lensing analysis, of a high-redshift galaxy-galaxy lensing system within the JWST-PEARLS/HST-TREASUREHUNT North Ecliptic Pole Time Domain Field (designated NEPJ172238.9+655143.1). The lensing geometry shears a $z=3.6\pm0.1$ star-forming galaxy into a near-Einstein ring with a radius of 0\farcs92, consisting of 4 primary images, around a foreground massive elliptical galaxy at $z=1.258\pm0.005$. The system is fortuitously located within the NIRISS F200W footprint of the PEARLS survey, enabling spectroscopic identification of the 8500A TiO band in the foreground galaxy and allowing tight constraints to be placed on the redshift of the background galaxy based on its continuum detection and lack of strong emission lines. We calculate magnification factors of $2.6<μ<8.4$ for the four images and a total lensing mass of $(4.08 \pm 0.07)\times10^{11}M_\odot$. SED fitting of the foreground elliptical galaxy within the Einstein radius reveals a stellar mass of $\sim1.26\times10^{11}M_\odot$, providing a mass/light ratio of 3.24. Employing simple scaling relations and assumptions, an NFW dark matter halo is found to provide the correct remaining mass within $0.12^{+0.21}_{-0.09}$dex. However, if a bottom-heavy IMF for elliptical galaxies is employed, stellar mass estimations increase and can account for the majority of the lensing mass (up to $\sim$83\%), reducing the need for dark matter. This system further demonstrates the new discovery space that the combined wavelength coverage, sensitivity and resolution of JWST now enables.

arXiv.org

These results raise the question where we can track down dark matter? What do we know in the least model-dependent way?
For strong lensing, the question has an answer, look at this video for a recent summary:
https://youtu.be/5FyaoYsCSVg?si=zmokA8g3XPCkoQwF

#astrophysics #astronomy #StrongGravitationalLensing #Cosmology #DarkMatter

Jenny Wagner (BASIC): Lensing of '69 -- Free gravitational lensing from its heuristic models

YouTube

2) the Bullet cluster is a more complicated structure than a binary system of two big dark-matter clumps that are offset to the baryons:
arxiv.org/abs/2503.21870
Masses were reduced and bounds on SIDM were set. Looks like we need less dark matter if the structure is more complex!

...and there is also a method to constrain dark matter properties purely from the multiple images, see this NASA press release for more:
https://science.nasa.gov/missions/hubble/double-galaxy-mystifies-hubble-astronomers/

#astrophysics #astronomy #StrongGravitationalLensing #Cosmology #DarkMatter

‘Double’ Galaxy Mystifies Hubble Astronomers

But NASA's Hubble Space Telescope uncovered what appears to be a pair of identical objects that look so weird it took astronomers several years to determine

NASA Science