Mastodawn

Hints of Primordial Magnetic Fields at Recombination and Implications for the Hubble Tension: https://arxiv.org/abs/2503.09599 -> Primordial magnetic fields could resolve the #HubbleTension and other cosmic mysteries: https://www6.slac.stanford.edu/news/2026-03-13-primordial-magnetic-fields-could-resolve-hubble-tension-and-other-cosmic-mysteries - an international team of researchers simulated magnetic forces in the early universe and found they could bridge the gap between the observed and calculated rates of the universe’s expansion.

Hints of Primordial Magnetic Fields at Recombination and Implications for the Hubble Tension

Primordial Magnetic Fields (PMFs), long studied as relics of the early Universe, accelerate recombination and have been proposed as a way to relieve the Hubble tension. However, previous studies relied on simplified toy models. Here we use recent evaluations of recombination with PMFs, incorporating full magnetohydrodynamic (MHD) simulations and detailed Lyman-alpha radiative transfer, to test PMF-enhanced recombination ($bΛ$CDM) against observational data from the cosmic microwave background (CMB), baryon acoustic oscillations (BAO), and Type Ia supernovae (SN). Focusing on non-helical PMFs with a Batchelor spectrum, we find a preference for present-day total field strengths of approximately 5-10 pico-Gauss. Depending on the dataset combination, this preference ranges from mild ($\sim 1.8σ$ with Planck + DESI) to moderate ($\sim 3σ$ with Planck + DESI + SH0ES-calibrated SN) significance. The $bΛ$CDM has Planck + DESI $χ^2$ values equal to or better than $Λ$CDM while predicting a higher Hubble constant. Future high-resolution CMB temperature and polarization measurements will be crucial for confirming or further constraining PMFs at recombination. Field strengths of 5-10 pico-Gauss align closely with those required for cluster magnetic fields to originate entirely from primordial sources, without the need for additional dynamo amplification.

arXiv.org

Christoph Minz Mar 3

The latest episode of #TheSupermassivePodcast is a great summary of the #HubbleTension. Is it just an experimental problem or a matter of the cosmological model?

https://shows.acast.com/the-supermassive-podcast/episodes/what-is-the-hubble-tension

#astronomy #cosmology

What is the Hubble Tension? | The Supermassive Podcast

Tom Zijlstra Feb 23

https://sailing-dulce.nl/home/article-9181 #HubbleTension #Supernova #sn2025wny #extreemweer #straalstroom #newyork Maandag 23-02-2026 Nog steeds een kwellend probleem in de astrofysica: de Hubble spanning. Dat heeft te maken met de snelheid waarmee het universum uitdijt. Het quotiënt van die snelheid en de gemeten afstand heet de Hubble constante. Hij wordt uitgedrukt in km/s per megaparsec. Ik schreef er vaker over; de laatste keer hier in 2022. Er zijn twee methoden om de constante te meten - de klassieke man..

Capitalmind Jan 23

Astronomy is facing a real #Cosmology crisis. New observations clash with theory: vast structures defy the #CosmologicalPrinciple, the #HubbleTension persists, and #JWST reveals mature galaxies far earlier than expected. Combined with puzzles in #DarkMatter and #DarkEnergy, the evidence suggests our standard model is incomplete. Rather than doom, this may be a historic “#MercuryMoment” — a rare phase where contradictions drive breakthroughs and reshape our view of the universe.

AlcorNews Dec 19

Un trou noir supermassif erre seul à travers l'univers à une vitesse folle : l'errance cosmique n'a jamais été aussi fascinante.
https://www.numerama.com/sciences/2145053-ce-trou-noir-supermassif-erre-seul-dans-lunivers-et-fonce-a-une-vitesse-hors-norme.html
#Space #Science #Innovation #Astrophysics #BlackHole #CosmicPhenomena #HubbleTension

Il file à 1 000 km/s : ce « monstre » invisible erre seul dans l'espace et défie les astronomes

Le télescope spatial James Webb a repéré un trou noir supermassif pas comme les autres : au lieu de rester bien sagement au centre d'une galaxie, il erre dans l'espace, seul. Autre mystère : il se déplace à une vitesse impressionnante. Le phénomène est difficile à imaginer : un trou noir supermassif 10 millions de

Numerama

AlcorNews Dec 18

L’ACT confirme la tension de Hubble : l’Univers s’étend trop vite selon les modèles. Le bug cosmique persiste, et ça dérange sérieusement.
https://www.geo.fr/sciences/expansion-de-l-univers-les-dernieres-donnees-de-l-atacama-cosmology-telescope-confirment-la-tension-de-hubble-230102
#Space #Science #Astrophysics #Cosmology #HubbleTension

Expansion de l'univers : les dernières données de l'Atacama Cosmology Telescope confirment la "tension de Hubble"

Les dernières données issues du télescope cosmologique d’Atacama ont été publiées. Les résultats des chercheurs permettent de mettre en lumière plusieurs avancées dans l'étude de la formation, la composition et l’évolution de l’univers.

Geo.fr

Tom Zijlstra Dec 9

https://sailing-dulce.nl/home/article-9101 #hubbleconstante #HubbleTension #kabinetsformatie #minderheidskabinet Dinsdag 09-12-2025 Al bijna honderd jaar worstelt de kosmologie met de Hubble-constante. Dat is de snelheid waarmee het universum uitbreidt. Het is nooit gelukt om die ondubbelzinnig vast te leggen. Het is een van de grootste vraagstukken in de moderne kosmologie. Ik schreef er herhaaldelijk over; voor het laatst drie jaar geleden hier. Het probleem begint ermee dat de Hubble-constante op twee manier..

In the Dark Oct 8

Everyone wants something better than ΛCDM

There’s a nice short review article on arXiv today by Mike Turner. I wasn’t going to share it because it hasn’t got any pictures in it, but changed my mind.

Here is the abstract

The current cosmological paradigm, ΛCDM, is characterized (b) its expansive description of the history of the Universe, its deep connections to particle physics and the large amounts of data that support it. Nonetheless, ΛCDM’s critics argue that it has been falsified or must be discarded for various reasons. Critics and boosters alike do agree on one thing: it is the not the final cosmological theory and they are anxious to see it replaced by something better! I review the status of ΛCDM, provide my views of the path forward, and discuss the role that the “Hubble tension” might play.

arXiv:2510.05483

To make up for the lack of pictures in the article, here’s the first image that came up when I did a search for “ΛCDM”:

#arXiv251005483 #Cosmology #HubbleTension #LambdaCDM #MikeTurner

Kev Abazajian Sep 29

Fun to work out with #UCIrvine graduate fellow Helena Garcia Escudero the details of why extra, sterile neutrinos are preferred (!!) by cosmology when adopting the local Cepheid measurement of the Hubble expansion rate. It ties into why baryon acoustic oscillations allow for simultaneous increase in relativistic energy density and neutrino mass, and it’s nontrivial why that happens. The paper will appear tomorrow on the arXiv, following up on a lead in our previous work https://arxiv.org/abs/2412.05451
#physics #astronomy #HubbleTension #cosmology #neutrinos #particlephysics