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

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.

The fediverse announcements follow:

Open Journal of Astrophysics

@[email protected]

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)

https://doi.org/10.33232/001c.146158

Open Journal of Astrophysics

@[email protected]

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)

https://doi.org/10.33232/001c.146159

Open Journal of Astrophysics

@[email protected]

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)

https://doi.org/10.33232/001c.146160

Open Journal of Astrophysics

@[email protected]

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)

https://doi.org/10.33232/001c.146161

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

@[email protected]

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)

https://doi.org/10.33232/001c.146033

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.

#ACT #arXiv250217674v2 #arXiv250217675v2 #arXiv250217676v2 #arXiv250217677v2 #arXiv250820904v2 #AtacamaCosmologyTelescope #cosmicShear #Cosmology #CosmologyAndNonGalacticAstrophysics #DarkEnergySpectroscopicInstrument #DECADECosmicShearProject #DESI #DiamondOpenAccess #DiamondOpenAccessPublishing #galaxyClustering #OpenAccess #OpenJournalOfAstrophysics #TheOpenJournalOfAstrophysics #thermalSunyaevZeldovichEffect #weakGravitationalLensing

Across the Universe - When it was a just-born
It seems yesterday (sob!)

Confirmed now to be 13.8 billion years (± 0.1%) before Internet, this kid is still growing-expanding since, at a confirmed rate of 67 - 68 km /second/megaparsec (± 3.26 million light years), i.e a galaxy at one megaparsec from Earth is receding from us at 67 to 68 kms/sec (± 241-245 000 km/h, just a little faster than my moped).

https://phys.org/news/2025-04-significance-baby-pictures-universe-years.html

#Hubble #AtacamaCosmologyTelescope #Toronto #Canada

ACT  maakt tot nu toe de helderste beelden van de kosmische microgolfachtergrond

Nieuwe afbeeldingen van de Atacama Cosmology Telescope laten het heelal zien toen het ongeveer 380.000 jaar oud was.

Een afbeelding van de CMB-straling van de Atacama Cosmology Teles

https://www.kuuke.nl/act-maakt-tot-nu-toe-de-helderste-beelden-van-de-kosmische-microgolfachtergrond/

#AtacamaCosmologyTelescope #HubbleConstante #HubbleSpanning #KosmischeMicrogolfachtergrondstraling #VroegeHeelal

Results from the Atacama Cosmology Telescope

Today is going to be a very busy day on the cosmology front – with the Euclid Q1 Data Release coming out at 11am GMT – but I’ll start off by sharing news of final data release (DR6) by the Atacama Cosmology Telescope. This was announced yesterday and includes former colleagues at Cardiff University, so congratulations to them and all concerned. Here is a pretty picture showing one of the beautiful cosmic microwave background polarization and intensity maps:

There are three related preprints on the arXiv today:

• The Atacama Cosmology Telescope: DR6 Maps (from which the above picture was taken).
• The Atacama Cosmology Telescope: DR6 Power Spectra, Likelihoods and ΛCDM Parameters
• The Atacama Cosmology Telescope: DR6 Constraints on Extended Cosmological Models

There’s a lot to digest in these papers but a quick skim of the abstracts gives two pertinent points. First, from the second paper:

We find that the ACT angular power spectra estimated over 10,000 deg2, and measured to arcminute scales in TT, TE and EE, are well fit by the sum of CMB and foregrounds, where the CMB spectra are described by the ΛCDM model. Combining ACT with larger-scale Planck data, the joint P-ACT dataset provides tight limits on the ingredients, expansion rate, and initial conditions of the universe.

They also find that, when combined with CMB lensing from ACT and Planck, and baryon acoustic oscillation data from the Dark Energy Spectroscopic Instrument (DESI Y1), the ACT data give a “low” value for the Hubble constant: H0=68.22 ± 0.36 km s-1 Mpc-1.

The third paper also says

In general, models introduced to increase the Hubble constant or to decrease the amplitude of density fluctuations inferred from the primary CMB are not favored by our data.

The “Hubble tension” remains!

#ACT #arXiv250314451 #arXiv250314452 #arXiv250314454 #AtacamaCosmologyTelescope #CosmicMicrowaveBackground #Cosmology #HubbleTension

The ACT-results are out! 🥳 It seems that the Atacama Cosmology Telescope supports everything we already know from WMAP & Planck... here are the publications:
https://arxiv.org/abs/2503.14452 (cosmology parameters)
https://arxiv.org/abs/2503.14454 (extensions beyond the standard model)

#cosmology #astrophysics #AtacamaCosmologyTelescope #CosmicMicrowaveBackground #CosmologicalConstant #CosmologicalPrinicple