June 12, 2026 Cosmology Talks episode hosted by Shaun Hotchkiss, with guest speaker Swagat Saurav Mishra, Senior Researcher at the Cosmology, Gravity and Astroparticle Physics Group, Centre for Theoretical Physics of the Universe (CTPU-CGA), affiliated with the Institute for Basic Science (IBS) in Daejeon (South Korea).

Papers:

[2605.27301] Effective Phantom Dark Energy: What Cosmological Reconstruction Does and Does Not Imply

[2507.07193] Braneworld Dark Energy in light of DESI DR2

Swagat’s website: A Physicist’s Action

Cosmology Talks Youtube channel

Four members of the Dark Energy Survey Collaboration discuss the latest findings. This talk is based on these two papers on the arXiv:

Main talk content: [2503.06712] Dark Energy Survey: implications for cosmological expansion models from the final DES Baryon Acoustic Oscillation and Supernova data

Newly released paper: [2601.14864] Dark Energy Survey: DESI-Independent Angular BAO Measurement

The authors:
Jessie Muir
Juan Mena-Fernández
Santiago Avila
Maria Vincenzi

Can gravitational waves get gravitationally lensed? The first ever detection of this might have just happened. This is especially cool because if we could routinely measure lensing of gravitational waves, we could use that to measure all sorts of other important things like the Hubble constant and precision tests of gravity to name just two. One of the interesting things you will hear about in today’s talk is an improved modeling of the candidate lens. This better nails down the probability that the wave really was lensed and even more fun gives insight into what astrophysical things the source and lens could be. In today’s talk, we’re joined by Miguel Zumalacarregui from the Max Plank Institute for Gravitational Physics in Potsdam, Germany to tell us about his new paper.

Miguel: miguelzuma.github.io

Paper: arXiv: 2512.17631

Ligo-Virgo-Kagra analysis: arXiv: 2512.16347

Sankarshana Srinivasan tells us about his work building the framework to constrain (or detect!) modified gravity using upcoming surveys. Building on earlier work developing model independent modified gravity simulations, Shankar now shows how a clever transform (the BNT transform) is able to better isolate the weak-lensing kernel, meaning one can more cleanly cut out the fully messy non-linear scales without losing too much usable information. We’re all looking forward to the talk in 3-5 years’ time applying these methods to Euclid and LSST data!

Paper: arXiv: 2409.06569

Cosmology Talk on earlier work in this series by Dan Thomas: The first model independent cosmological simulations of modified gravity

Cosmology Talks is hosting a mini-workshop on Thursday 10 April at 18:00 UTC about DESI DR2 Cosmology.

The workshop will be purely discussion based, and framed around the recent DESI DR2 papers and the talks listed below. Most of the speakers from the talks will be present, as well as some invited experts on related fields.

Important! It is not expected that the talks and papers are fully understood by all participants, but the contents of either the relevant Cosmology Talks video or video 1 and video 2 from DESI’s YouTube channel will be assumed to be common knowledge of all participants before the discussion begins. This provides a common starting position for discussion among all attendees.

Questions/thoughts are, however, welcome on any of the recent DESI papers, or talks listed below.

Cosmology Talks: DESI 2025 – Cosmology Results from DR2 BAO (Garcia-Quintero & Martini)

DESI’s YouTube Channel:

1. DESI shakes up the dark Universe: An overview
2. DESI DR2 Results: Measurements of Baryon Acoustic Oscillations and Cosmological Constraints

3. Extended Dark Energy analysis using DESI DR2 BAO measurements
4. DESI DR2 Baryon Acoustic Oscillations from Galaxies and Quasars
5. DESI DR2: Validation of the Lyman alpha BAO analysis using synthetic datasets
6. Dark Energy Spectroscopic Instrument Survey Data Release 1
7. DESI DR2 results: Baryon Acoustic Oscillations from the Lyman-alpha forest
8. Combined Clustering and Weak Lensing from the DESI Year-1 Dataset and Stage III Lensing Surveys
9. Neutrino masses from the latest DESI results

The schedule is (starting at 18:00 UTC):

• 10 minutes (approx) introducing the workshop format.
• 50 minutes discussion in one Zoom room.
• 10 minutes (approx) break time.
• 50 minutes of multiple discussions, in breakout rooms, based on ideas that arose during the earlier discussion.

Pre and post-discussion will take place in the Cosmo Discussion Mattermost space, in the Cosmology Talks channel. The speakers and invited experts will also be present there to ask questions.

Participation at the workshop is open to all cosmologists and researchers from neighbouring fields.

Zoom: https://zoom.cosmologytalks.com/

Angus Wright, Benjamin Stölzner, Robert Reischke, Marika Asgari and Konrad Kuijken tell us about the final cosmology results from the Kilo Degree Survey (KiDS-Legacy). After exhaustive improvement of their analysis, and consistency tests, and a six month wander in the B-Mode wilderness they emerge with no S8 tension at all.

Angus: anguswright.github.io
Benjamin: inspirehep.net/authors/1944983
Robert: inspirehep.net/authors/2219647
Marika: ncl.ac.uk/…marikaasgari.html
Konrad: universiteitleiden.nl/…koen-kuijken

KiDS: kids.strw.leidenuniv.nl

Papers:
2503.19442
2503.19441
2503.19440

Teresa Matamoro, Mike Walmsley and Phil Holloway tell us about three key areas Euclid has shed a scientific light on in their Q1 data release today. These are active galactic nuclei, galaxy morphology and strong lensing.

Teresa: linkedin/teresamatamoro…

Mike: walmsley.dev

Phil: physics.ox.ac.uk/…

ESA details on the Q1 release: cosmos.esa.int/…

Euclid Consortium details on the Q1 release: euclid-ec.org…

Papers:

[2503.15326] Euclid Quick Data Release (Q1). The Strong Lensing Discovery Engine C – Finding lenses with machine learning

[2503.15324] Euclid Quick Data Release (Q1): The Strong Lensing Discovery Engine A — System overview and lens catalogue

[2503.15320] Euclid Quick Data Release (Q1). The active galaxies of Euclid

[2502.06505] Euclid: A complete Einstein ring in NGC 6505

[2404.02973] Scaling Laws for Galaxy Images

The space observatory Euclid is producing and sharing results. In this video Guadalupe Cañas-Herrera and Hervé Aussel tell us about Euclid, its science goals and the Q1 data set they have released today (19-Mar-2025).

Guadalupe: gcanasherrera.com

Hervé: inspirehep.net/authors/1038805

ESA details on the Q1 release: cosmos.esa.int/…

Euclid Consortium details on the Q1 release: euclid-ec.org…

Papers:

[2503.15302] Euclid Quick Data Release (Q1) – Data release overview

[2503.15306] Euclid Quick Data Release (Q1). Photometric redshifts and physical properties of galaxies through the PHZ processing function

[2503.15307] Euclid Quick Data Release (Q1): From spectrograms to spectra: the SIR spectroscopic Processing Functio

[2503.15308] Euclid Quick Data Release (Q1) – Characteristics and limitations of the spectroscopic measurements

[2503.15321] Euclid Quick Data Release (Q1). Active galactic nuclei identification using diffusion-based inpainting of Euclid VIS images

Cristhian Garcia Quintero and Paul Martini tell us about the baryon acoustic oscillation measurements in data release two (DR2) of the Dark Energy Spectroscopic Instrument (three years of data). As with the first data release they are seeing evidence for evolving dark energy. They now see it when combining with just CMB, or with “just” Dark Energy Survey supernovae and clustering data.

Relevant papers on the arXiv: Continue reading →

Arnaud de Mattia, Hector Gil-Marín and Pauline Zarrouk tell us about the latest DESI key papers. These ones are covering the “full shape” of the galaxy power spectrum. This is in contrast to their results from April, which were centred around the Baryon Acoustic Oscillation (BAO) feature.

The analysis is an absolute tour de force, explaining why the video is so long. DESI have done a lot of analysis and it takes a while to unpack. (The raw recording of this video was more than 200 minutes long!)

The results aren’t quite so eye-opening as the BAO ones were in April. The evidence for evolving dark energy is still there, but the significance of this evidence hasn’t changed much. They are however able to do a bunch of tests of modified gravity and find that, unlike ΛCDM, General Relativity appears to be in great shape (at least as far as DESI observations are concerned). Continue reading →