Archive for the The Universe and Stuff Category

Euclid Update – Revised Timeline

Posted in Euclid, mathematics, The Universe and Stuff with tags , , , , , , , , on June 16, 2026 by telescoper

In a post last week I hinted that I hoped soon to be able to provide an update on progress with the European Space Agency’s Euclid Mission. People within the Euclid Consortium have known for some time, but it has now been officially announced by ESA, that the timeline for the first full Data Release (DR1; originally scheduled for October 2026) has now been revised.

The plan now is for DR1 to happen in stages, with a first tranche to occur in November 2026 (precise date yet to be announced). The complete data release will take place in mid-2027 (probably in June). The sky area covered by DR1 will be about covering a large sky area of about 1900 deg².

To give a little more background, the data products from the Euclid survey are divided into three levels of data processing function:

  • LE1 – the “raw” data frames, prior to calibration, generated at the Science Operations Centre from the time-ordered data and telemetry received from the spacecraft
  • LE2 – the calibrated and corrected data for the two instruments (VIS and NISP) – images, spectra, catalogues of point sources, etc
  • LE3 – the high-level data products (galaxy catalogues, cosmic shear maps, etc) designed for cosmological analysis

The first release will comprise LE1 and LE2 only. This will be called DR-Foundation. The LE3 data will be added next year to make the full DR1. Since LE3 is required for the cosmological analysis that is the prime motivation for the Euclid mission, it follows that there will be no official cosmology results from Euclid DR1 until mid-2027 at the earliest. Other results based on “Foundation” data may of course emerge before then.

I hope this clarifies the situation.

P.S. Irish physicists and astronomers will be particularly interested to know that the LE1 data includes information about the spacecraft and instrument pointing orientations, which is stored in the form of quaternions

For Retired Engineers…

Posted in Biographical, The Universe and Stuff with tags , , , , on June 14, 2026 by telescoper

Many moons ago, just before I moved from Cardiff for my stint at Sussex University, I decided to ditch all the unsolicited letters and manuscripts I’ve accumulated over the years about “alternative” theories of relativity, cosmology, and whatnot. I don’t know why I had kept so many of them for so long, but I no longer have most of them. I did keep one or two of the best ones, however. Here’s an example:

I could never make head nor tail of this, but sometimes had a vague feeling that it might just be a sort of cosmic Rosetta Stone, offering up the Secrets of the Universe in diverse languages. Sadly, however, it’s more likely that the languages involved are Balderdash, Gibberish and Gobbledegook. At the time I wrote:

I regret to announce, therefore, that the plethora of papers telling me why Einstein was wrong, how the Universe is really in the shape of a spiral, how the Great Pyramid of Giza explains the Higgs Boson, and why the Big Bang couldn’t have happened, will have to go to the Great Shredder in the Sky (if that’s where it is).

Anyway, to all my correspondents all I can say is that I’ve enjoyed reading your letters – you must be very fond of your old typewriters – and I’m grateful for the time you took to draw the diagrams by hand in so many lovely colours. And I’m impressed by your qualifications as Electrical Engineers. Really. I’m sorry I didn’t reply to you all individually, but I just didn’t have the time. And now it pains me to realise I don’t have the space either…

I still get such things, of course, but they always come by email nowadays and usually end up in the spam folder, where I do not disturb them. I never reply, of course. Life’s too short.

I know I’m not the only one to have noticed the fact that many – indeed most – such correspondents are Electrical Engineers (usually retired). I was delighted therefore to see that there’s now a nice little paper on arXiv by David Garfinkle with the title Relativity for Retired Engineers and the abstract:

We provide some guidance and examples to clear up common misconceptions about special relativity. These misconceptions often come from trying to express the truths of special relativity in Newtonian terms rather than in terms more natural to special relativity itself. This conceptual stance can also help in attaining a better understanding of general relativity.

Readers may consider referring their correspondents to this source…

Weekly Update from the Open Journal of Astrophysics 13/06/2026

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , , , , , , , , , , , , , , , , , , , on June 13, 2026 by telescoper

It’s Saturday again so it’s time for another update of activity at the Open Journal of Astrophysics. Since the last update we have published a further three papers, bringing the number in Volume 9 (2026) to 122 and the total so far published by OJAp up to 570.

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 Thursday 11th June, is “Dancing Streams In Merging Halos: Stellar Streams in a MW–LMC-like merger” by (all based in the USA): Sachi Weerasooriya (Carnegie Observatories), Tjitske Starkenburg (Northwestern U.), Emily C. Cunningham (Columbia U.) & Kathryn V. Johnston (Flatiron Institute). This article explores how galaxy mergers, like the Milky Way-Large Magellanic Cloud merger, significantly alter the properties and structures of stellar streams, challenging the recovery of their initial orbits. It is in the folder marked Astrophysics of Galaxies.

The overlay for this paper is here

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

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "Dancing Streams In Merging Halos: Stellar Streams in a MW–LMC-like merger" by (all based in the USA): Sachi Weerasooriya (Carnegie Observatories), Tjitske Starkenburg (Northwestern U.), Emily C. Cunningham (Columbia U.) & Kathryn V. Johnston (Flatiron Institute).

doi.org/10.33232/001c.163211

June 11, 2026, 7:05 am 1 boosts 0 favorites

The second paper for this week, also published on Thursday 11th June but in the folder Cosmology and Nongalactic Astrophysics is “X-SORTER (X-ray Survey Of meRging clusTErs in Redmapper): X-ray and Spectroscopic Characterization of 12 Optically Selected Galaxy Cluster Merger Candidates” by Christopher Hopp, David Wittman, Rodrigo Stancioli, Zhuoran Gao & Faik Bouhrik (UC Davis) and Scott Adler (Rochester), all based in the USA. The X-SORTER program identifies merging galaxy clusters to study dark matter interactions, using optical indicators and X-ray observations. This method efficiently identifies active clusters suitable for detailed dark matter studies.

The overlay for this one looks like this:

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

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "X-SORTER (X-ray Survey Of meRging clusTErs in Redmapper): X-ray and Spectroscopic Characterization of 12 Optically Selected Galaxy Cluster Merger Candidates" by Christopher Hopp, David Wittman, Rodrigo Stancioli, Zhuoran Gao & Faik Bouhrik (UC Davis) and Scott Adler (Rochester), all based in the USA.

doi.org/10.33232/001c.163212

June 11, 2026, 7:25 am 1 boosts 0 favorites

The third and final paper of the week, published on Friday 12the June in the folder Earth and Planetary Astrophysics, is “JCMT Constraints on the Early-Time HCN and CO Emission and HCN Temporal Evolution of 3I/ATLAS” by Jason T. Hinkle (U. Illinois, USA) and 6 others based in the USA and Chile. This article presents observations of the third Interstellar Object, 3I/ATLAS, providing early sub-mm constraints on its activity. The findings suggest a steeper production rate slope than typical Solar System comets.

The overlay for this one is here:

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

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "JCMT Constraints on the Early-Time HCN and CO Emission and HCN Temporal Evolution of 3I/ATLAS" by Jason T. Hinkle (U. Illinois, USA) and 6 others based in the USA and Chile.

doi.org/10.33232/001c.163250

June 12, 2026, 6:50 am 1 boosts 2 favorites

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

Euclid, Gravitational Lensing, and Dark Matter

Posted in Euclid, The Universe and Stuff with tags , , on June 11, 2026 by telescoper

I’ve been slow onto a result which was announced last week concerning the detection weak gravitational lensing in the cluster Abell 2390 by the Euclid spacecraft and its use to determine the distribution of dark matter in the cluster. You can find a full discussion of the result here and the scientific paper is here.

The analysis was based on Early Release Observations of the cluster, a pretty picture of which are shown here:

Credit: ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi.

(The little blue patches are artefacts caused by internal reflections in the VIS instrument and can be dealt with in software.)

According to general relativity, the presence of any mass bends the path of light passing near it, producing gravitational lensing. The most famous examples of this are the giant arcs and multiple images associated with strong gravitational lensing, but these are very rare as they require good alignment between observer, lens and source.. Most lines of sight in the universe do not satisfy this condition so are in the weak lensing regime. Even in such cases, however, the presence of the foreground mass can be detected, by way of a systematic alignment in the orientation of background sources around the lensing mass. A circular background image would be distorted into an ellipse by this process. Unfortunately galaxies aren’t circular but are approximately elliptical, so the shape of each source is changed from an ellipse to differently shaped ellipse. The distortion is therefore impossible to detect in a single background source because we don’t know the intrinsic orientation of the galaxy, but the distortion of different sources is correlated in a particular way. Weak gravitational lensing is thus an intrinsically statistical measurement, but it provides a way to measure the masses of astronomical objects without requiring assumptions about their composition or dynamical state. Weak gravitational lensing observations are, however technically difficult to carry out and analyse, as one has to be very careful that no correlations are introduced by systematic errors in the optics.

Anyway, they say that a picture paints a thousand words so here are two pictures. On the left we see the shear axes as extracted from the above image and on the right the inferred dark matter distribution. You can slide the bar backwards and forwards to see how the two images relate.

Shear map (left) and inferred dark matter distribution (right)

You can see that the shear tends to be aligned tangentially to a line connecting the image to the cluster centre (in the plane of the sky), which is what theory would predict.

There’ll be much more of this sort of analysis in the full Euclid Survey. I hope to be able to give an update about this reasonably soon.

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

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , , , , , , , , , , , , , , , , , , , on June 6, 2026 by telescoper

Another Saturday, 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 119 and the total so far published by OJAp up to 567.

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 Tuesday 2nd June, is “The impact of the formation channel on gravitational-wave-galaxy cross-correlations” by Kabir Chakravarti (Chennai Mathematical Institute, India) and Federico R Urban (CEICO-FZU, Czech Republic). This article, published in the folder Cosmology and Nongalactic Astrophysics, explores how uncertainties in binary formation affect the cross-correlation signal between gravitational wave events and galaxy catalogues, finding that time-delay distribution significantly impacts the signal.

The overlay for this paper is here

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

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "The impact of the formation channel on gravitational-wave-galaxy cross-correlations" by Kabir Chakravarti (Chennai Mathematical Institute, India) and Federico R Urban (CEICO-FZU, Czech Republic)

doi.org/10.33232/001c.162783

June 2, 2026, 7:22 am 1 boosts 2 favorites

The second paper for this week, also published on Tuesday 2nd June but in the folder High-Energy Astrophysical Phenomena, is “Transient X-ray Sources as Extremely Eccentric Mass-Transfer Binaries with Compact Companions” by Jonathan I Katz and Michael A Nowak (Washington University, St Louis, USA). This article suggests that X-ray transients, similar to tidal disruption events, are produced in eccentric stellar-compact object binaries, with their frequency gradually increasing over time.

The overlay for this one looks like this:

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

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "Transient X-ray Sources as Extremely Eccentric Mass-Transfer Binaries with Compact Companions" by Jonathan I Katz and Michael A Nowak (Washington University, USA)

doi.org/10.33232/001c.162784

June 2, 2026, 7:44 am 1 boosts 1 favorites

Next one up, the third paper of the week, also published on Tuesday 2nd June in the folder High-Energy Astrophysical Phenomena is “Resolving the (Debate About) Nozzle Shocks in Tidal Disruption Events” by Zachary L. Andalman & Eliot Quataert (Princeton U., USA), Eric R. Coughlin (Syracuse U. USA) and C. J. Nixon (U. Leeds, UK). This paper presents a model to understand the role of nozzle shocks in the circularization of stellar debris during a tidal disruption event when a star approaches a supermassive black hole (SMBH)

The overlay for this one is here:

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

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "Resolving the (Debate About) Nozzle Shocks in Tidal Disruption Events" by Zachary L. Andalman & Eliot Quataert (Princeton U., USA), Eric R. Coughlin (Syracuse U. USA) and C. J. Nixon (U. Leeds, UK)

doi.org/10.33232/001c.162785

June 2, 2026, 7:52 am 1 boosts 1 favorites

The fourth paper this week, published on Wednesday 3rd June in the folder Cosmology and Nongalactic Astrophysics, is “Validating Digital Twins of the Local Universe with the Thermal Sunyaev-Zel’dovich Signal” by Richard Stiskalek (University of Oxford, UK) and Harry Desmond (University of Portsmouth, UK). The thermal Sunyaev-Zel’dovich effect and constrained simulations are used to analyze the thermal pressure of ionized gas in galaxy clusters and produce a set of digital twins for cosmological study.

The overlay is here:

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

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "Validating Digital Twins of the Local Universe with the Thermal Sunyaev-Zel’dovich Signal" by Richard Stiskalek (U. Oxford, UK) and Harry Desmond (U. Portsmouth, UK)

doi.org/10.33232/001c.162811

June 3, 2026, 5:15 am 1 boosts 1 favorites

The fifth and final paper this week, published on Thursday 4th June in the folder Cosmology and Nongalactic Astrophysics is “Photon (Non)Conservation in the Reduced Speed of Light Approximation and How to (Almost) Fix It” by Nickolay Y. Gnedin (University of Chicago, USA). The “Reduced Speed of Light” approximation in cosmological simulations can lead to photon non-conservation, and while some missing photons can be counted, adding them back is challenging.

The overlay for this one is here:

The officially accepted version of this paper can be found on arXiv here and Mastodon announcement here

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "Photon (Non)Conservation in the Reduced Speed of Light Approximation and How to (Almost) Fix It" by Nickolay Y. Gnedin (U. Chicago, USA)

doi.org/10.33232/001c.162879

June 4, 2026, 11:20 am 2 boosts 1 favorites

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

Eclipse Event – a Date for your Diaries!

Posted in The Universe and Stuff, Maynooth with tags , , , , , on June 2, 2026 by telescoper

Here’s an invitation to people interested in astronomy to join staff from the Department of Physics at Maynooth University on Wednesday, August 12th 2026 from 5:30 pm to 8:30 pm for a special public celebration of one of the deepest solar eclipses visible from Ireland in decades. The next eclipse with > 90% obscuration of the Sun by the Moon won’t be seen again in Ireland until 2090, by which time I will have retired.

Experience the eclipse safely through:

  • eclipse viewing glasses
  • solar telescopes
  • live astronomy demonstrations

List of Solar Talks during the evening:

  • Dr. Emma Whelan – The Story of the Sun
  • Dr. Joshuah Heath – The Quantum Sun
  • Dr. Marcin Gradziel – (Electric) Power from the Sun. The good, the bad, and the glinty!
  • Dr. Michelle McCrystall – The star of the show: How the Sun drives our climate
  • Prof. Peter Coles – Einstein and the Eclipse (Who He? Ed.)
  • Dr. Patrick Kavanagh – Will our Sun go Supernova?

The evening will also include:

  • an immersive* astronomy show in our inflatable planetarium
  • hands-on arts and crafts activities for children

*especially if it rains

Maynooth University Staff can reserve a place here until June 14th, after which booking will be opened to the general public – I’ll repost this invitation with a link at that time.

Weekly Update from the Open Journal of Astrophysics – 30/05/2026

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

It’s Saturday once again, so it’s time for another update of activity at the Open Journal of Astrophysics. Since the last update we have published a further four papers, bringing the number in Volume 9 (2026) to 114 and the total so far published by OJAp up to 562.

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 25th May is “Little Red Dot – Host Galaxy = Black Hole Star: A Gas-Enshrouded Heart at the Center of Every Little Red Dot” by Wendy Q. Sun (MIT, USA) and 32 others from around the world. This study presents evidence that “black hole stars” (BH*), early stages of black hole growth, power Little Red Dots (LRDs) and every massive black hole may have been a BH*.

The overlay for this paper is here

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

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "Little Red Dot – Host Galaxy = Black Hole Star: A Gas-Enshrouded Heart at the Center of Every Little Red Dot" by Wendy Q. Sun (MIT, USA) and 32 others from around the world.

doi.org/10.33232/001c.162505

May 25, 2026, 7:13 am 1 boosts 0 favorites

The second paper for this week, also published on Monday 25th May but in the folder Cosmology and Nongalactic Astrophysics, is “Catalog-based detection of unrecognized blends in deep optical ground based imaging” by Shuang Liang (Stanford U., USA) and Prakruth Adari & Anja von der Linden (Stony Brook U., USA) on behalf of the LSST Dark Energy Science Collaboration. The study uses machine learning to detect unrecognized blends in deep ground-based imaging, improving sample purity and potentially enhancing accuracy in future cosmological surveys.

The overlay for this one is here:

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

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "Catalog-based detection of unrecognized blends in deep optical ground based imaging" by Shuang Liang (Stanford U., USA) and Prakruth Adari & Anja von der Linden (Stony Brook U., USA) on behalf of the LSST Dark Energy Science Collaboration

doi.org/10.33232/001c.162504

May 25, 2026, 7:30 am 1 boosts 1 favorites

Next one up, the third paper of the week, published on Tuesday 26th May in the folder Cosmology and Nongalactic Astrophysics is “Control variates from Eulerian and Lagrangian perturbation theory: Application to the bispectrum” by Nickolas Kokron and Shi-Fan Chen (Institute for Advanced Study, Princeton, USA). This paper hexplores the use of control variates in cosmological simulations, introducing a new ‘shifted control variate’ that improves precision and enables accurate bispectrum emulators, aiding in cosmology modeling.

The overlay for this one is here:

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

Open Journal of Astrophysics

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)

doi.org/10.33232/001c.162336

May 18, 2026, 7:04 am 1 boosts 0 favorites

The fourth and final paper this week, also published on Tuesday 26th May is “How precisely can we measure the ages of subgiant and giant stars?” by Cheyanne Shariat, Kareem El-Badry and Soumyadeep Bhattacharjee (California Institute of Technology, USA). This article, published in the folder Solar and Stellar Astrophysics, is about testing the accuracy of stellar age estimates from recent catalogs, finding that spectroscopic metallicities provide reliable subgiant ages, while photometric ages underestimate uncertainties. Accurate chemical abundance measurements are essential.

The overlay is here:

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

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "How precisely can we measure the ages of subgiant and giant stars?" by Cheyanne Shariat, Kareem El-Badry and Soumyadeep Bhattacharjee (California Institute of Technology, USA)

doi.org/10.33232/001c.162534

May 26, 2026, 7:05 am 1 boosts 0 favorites

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

Weekly Update from the Open Journal of Astrophysics – 23/05/2026

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , on May 23, 2026 by telescoper

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:

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "Edges In Coadded Images" by Erin Sheldon (Brookhaven National Laboratory, USA)

doi.org/10.33232/001c.162176

May 18, 2026, 6:43 am 1 boosts 0 favorites

The second paper for this week, also published on Monday 18th May but in the folder Cosmology and Nongalactic Astrophysics, is “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 other authors from all round the world. This paper presents a cosmological analysis of correlations between the DESI-DR1 Bright Galaxy Survey and Luminous Red Galaxy samples and overlapping shear measurements from various weak lensing surveys.

The overlay for this one is here:

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

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "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.

doi.org/10.33232/001c.162334

May 18, 2026, 6:52 am 1 boosts 1 favorites

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:

Open Journal of Astrophysics

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)

doi.org/10.33232/001c.162336

May 18, 2026, 7:04 am 1 boosts 0 favorites

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:

Open Journal of Astrophysics

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)

doi.org/10.33232/001c.162407

May 20, 2026, 2:52 pm 0 boosts 2 favorites

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:

Open Journal of Astrophysics

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)

doi.org/10.33232/001c.162454

May 22, 2026, 8:31 am 0 boosts 1 favorites

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:

Open Journal of Astrophysics

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)

doi.org/10.33232/001c.162455

May 22, 2026, 8:59 am 0 boosts 0 favorites

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

Weekly Update from the Open Journal of Astrophysics – 16/05/2026

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , , , , , , , , , , , , , , , , , , , , , , , on May 16, 2026 by telescoper

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:

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "Triaxial magnetars as sources of fast radio bursts" by Jonathan I Katz (Washington University, USA)

doi.org/10.33232/001c.162006

May 11, 2026, 7:32 am 0 boosts 0 favorites

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:

Open Journal of Astrophysics

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)

doi.org/10.33232/001c.162091

May 12, 2026, 6:07 am 1 boosts 3 favorites

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:

Open Journal of Astrophysics

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)

doi.org/10.33232/001c.162093

May 12, 2026, 6:37 am 1 boosts 1 favorites

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:

Open Journal of Astrophysics

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)

doi.org/10.33232/001c.162107

May 13, 2026, 7:44 am 1 boosts 1 favorites

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:

Open Journal of Astrophysics

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)

doi.org/10.33232/001c.162135

May 13, 2026, 7:48 am 1 boosts 0 favorites

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

After Lectures but before Examinations

Posted in Education, Maynooth, The Universe and Stuff with tags , , on May 14, 2026 by telescoper

This morning I did my last teaching session of the Academic Year 2025-6, an informal revision lecture/tutorial on Computational Physics. It was optional, for the students, as this is officially a study break, and was at 9am, and only a handful of students showed up, but I hope those that did found it useful. As is often the case with optional sessions, I think the students who came were the keenest and probably therefore those who least needed last-minute tips for the examination, but that’s always the way.

In the past such revision classes have been routine, at least for me, but for some reason the University has taken to locking most of the teaching rooms during the study break. This causes huge problems finding a space to do revision sessions. I really don’t understand this. There are constant complaints from students about the lack of study space, and the response from the University is that right before the examinations they lock dozens of empty rooms.

Anyway, the Examination Period starts tomorrow morning, Friday15th, but most of the students who turned up this morning have their first examination on Tuesday 19th May (which happens to be Computational Physics).

take the opportunity to wish all students the best for their examinations:

You shouldn’t really be relying on luck of course, so here are some tips (especially for physics students, but applicable elsewhere).

  1. Try to get a good night’s sleep before the examination and arrive in plenty of time before the start. Spending all night cramming is unlikely to help you do well.
  2. Prepare well in advance so you’re relaxed when the time comes.
  3. Read the entire paper before starting to answer any questions. In particular, make sure you are aware of any supplementary information, formulae, etc, given in the rubric or at the end. You can always ask for log tables if there’s something you can’t remember.
  4. Start off by tackling the question you are most confident about answering, even if it’s not Question 1. This will help settle any nerves. You’re under no obligation to answer the questions in the order they are asked.
  5. Don’t rush! Students often lose marks by making careless errors. In particular, check all your working out, including numerical results obtained your calculator, at least twice
  6. Please remember the UNITS!
  7. Don’t panic! You’re not expected to answer everything perfectly. A first-class mark is anything over 70%, so don’t worry if there are bits you can’t do. If you get stuck on a part of a question, don’t waste too much time on it (especially if it’s just a few marks). Just leave it and move on. You can always come back to it later.