Lmst

#HubbleTension
Measuring an intermediate value between two disagreeing values does not solve the tension between those numbers!

"Webb telescope helps refine Hubble constant, suggesting resolution to long-standing expansion rate debate"
🔗https://phys.org/news/2025-05-webb-telescope-refines-hubble-constant.html

A nice piece in The Atlantic about Adam Reiss, who helped establish the standard model of cosmology and now anticipates its overthrow:
https://www.theatlantic.com/science/archive/2025/05/adam-riess-hubble-tension/682980/?gift=TCdGb93Qc4nVepj3DCKKPrRLXx3DY6pzZkmwCujaCg4&utm_source=copy-link&utm_medium=social&utm_campaign=share

And a summary of new data from the Web Telescope that further supports the standard model:

Summary: https://scitechdaily.com/hubble-trouble-solved-webb-telescope-finally-cracks-the-universes-growth-mystery/

Original paper: https://iopscience.iop.org/article/10.3847/1538-4357/adce78

#Science #Cosmology #HubbleTension

New measure of the universe’s expansion suggests resolution of a conflict | University of Chicago News #hubbletension

https://news.uchicago.edu/story/new-measure-universes-expansion-suggests-resolution-conflict

Delighted to share a new cosmology preprint:

Time-Activated Planck Cosmology (TAP) offers a geometric alternative to inflation via causal activation driven by a scalar field 𝜏(𝑡).

It reproduces the red tilt and CMB peaks, and predicts 𝑟=0, suppressed 𝜎8, and τ-gradient lensing.

Feedback welcome from anyone exploring the early universe, CMB, or modified gravity.

👉 https://doi.org/10.5281/zenodo.15461665

#cosmology #CMB #inflation #astroPh #physics #openscience #HubbleTension

https://www.geo.fr/sciences/et-si-la-matiere-noire-evoluait-avec-le-temps-une-nouvelle-piste-de-comprehension-de-l-univers-226582
#MatièreNoire #TensionDeHubble #ÉnergieNoire #CornellUniversity #ChampsScalaires #UniversOscillant #ConstanteDeHubble #HubbleTension #DarkMatter #OscillatingDarkMatter #TimeDependentCosmology #HubbleConstant #ModifiedGravity #QuantumCosmology #DarkSector

The CosmoVerse: The White Paper

Newly announced on arXiv there is a review article with the title The CosmoVerse White Paper: Addressing observational tensions in cosmology with systematics and fundamental physics. The abridged form of the abstract reads:

The standard model of cosmology has provided a good phenomenological description of a wide range of observations both at astrophysical and cosmological scales for several decades. This concordance model is constructed by a universal cosmological constant and supported by a matter sector described by the standard model of particle physics and a cold dark matter contribution, as well as very early-time inflationary physics, and underpinned by gravitation through general relativity. There have always been open questions about the soundness of the foundations of the standard model. However, recent years have shown that there may also be questions from the observational sector with the emergence of differences between certain cosmological probes. In this White Paper, we identify the key objectives that need to be addressed over the coming decade together with the core science projects that aim to meet these challenges. These discordances primarily rest on the divergence in the measurement of core cosmological parameters with varying levels of statistical confidence. These possible statistical tensions may be partially accounted for by systematics in various measurements or cosmological probes but there is also a growing indication of potential new physics beyond the standard model. After reviewing the principal probes used in the measurement of cosmological parameters, as well as potential systematics, we discuss the most promising array of potential new physics that may be observable in upcoming surveys. We also discuss the growing set of novel data analysis approaches that go beyond traditional methods to test physical models.
arXiv:2504.01669v2

Here’s a plot demonstrating one of the tensions discussed in this paper, and widely on this blog, the Hubble Tension:

This is a very comprehensive review article consisting of over 400 pages and having over 400 authors. I expect all of you to read it over the weekend. There will be a test on Monday.

*One of whom happens to be a PhD student of mine.

#arXiv250401669v2 #Cosmology #CosmoVerse #HubbleTension

A new study suggests the universe might be rotating—could this solve the Hubble tension? #Cosmology #HubbleTension #RotatingUniverse

https://geekoo.news/is-the-universe-gently-spinning-new-clues-from-hawaii/

Nice read again from Triton Station.

"... that perhaps the reason we have to invoke the twin tooth fairies of dark matter and dark energy is to get FLRW to approximate some deeper, underlying theory.

https://tritonstation.com/2025/04/17/some-persistent-cosmic-tensions/

#cosmology #hubbletension #lcdm #flrw #tritonstation

#Cosmology

Do ongoing tensions leave room for new physics?

One century after Edwin Hubble revealed his astonishing discovery of a cosmos beyond the Milky Way, the most precise measurements still can’t agree on how fast galaxies are moving.

By Wendy Freedman
https://www.nature.com/articles/d41586-025-00896-5

#HubbleTension #HubbleConstant #Physics #Astronomy #Astrophysics #Astrodon #Science #STEM

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:

Intensity and Polarization maps from ACT: arXiv:2503.14451

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

#HubbleTension #HubleCrisis
"Turning the Hubble tension into a crisis: New measurement confirms universe is expanding too fast for current models"

Time to add another epicycle to LCDM!

🔗https://phys.org/news/2025-01-hubble-tension-crisis-universe-fast.html

How fast is the Universe expanding? This astronomer took cosmology closer to an answer

Wendy Freedman is part of Nature’s 10, a list of people who shaped science in 2024.

https://www.nature.com/articles/d41586-024-03899-w

#Cosmology #HubbleTension #HubbleConstant #Science #Nature #astronomer #astronomi #astrophysics #STEM #WomeninSTEM #Womeninscience #Universe

#HubbleTension #Cosmology #JWST #HST
"Measuring the Hubble constant through the galaxy pairwise peculiar velocity"
<Our results yield H0 = 75.5±1.4 km/s/Mpc>

A new method for measuring the Hubble constant.
Their value is at 5.8σ tension with Planck!

Accepted for publication in ApJL
🔗https://arxiv.org/abs/2412.04660

Webb Researchers Discover Lensed Supernova, Confirm Hubble Tension

https://webbtelescope.org/contents/early-highlights/webb-researchers-discover-lensed-supernova-confirm-hubble-tension

#Cosmology #JWST #HubbleConstant #HubbleTension #Universe #Astrodon #science #news

On France Culture today: The Hubble Tension

... in an interview by the excellent Celine Loozen I talk about our Cosmicflows-4 measurement of the Hubble Constant, as well as the value inferred from Ho'oleilana, that are both exacerbating the tension.

▶ at t=33:30 https://www.radiofrance.fr/franceculture/podcasts/la-science-cqfd/constante-de-hubble-la-tension-monte-7710009

#Cosmology #Hubble #HubbleConstant #HubbleTension #Hooleilana #science #Astrodon

#SH0ES team respond to the paper by Wendy Freedman et al (arXiv:2408.06153) that suggested the #HubbleTension may be over. TLDR: nope not yet. 🧵 with paper at https://bsky.app/profile/styrofoamplates.bsky.social/post/3l2cten7dip2f , and see also this, compiled from the bad place https://threadreaderapp.com/thread/1826593092901712201.html #astrodon

New #analysis of #Webbdata measures #universe expansion rate, finds there may not be a '#Hubbletension'

https://phys.org/news/2024-08-analysis-webb-universe-expansion-hubble.html?utm_source=nwletter&utm_medium=email&utm_campaign=daily-nwletter

Back in April I posted about a meeting at the Royal Society in London called Challenging the Standard Cosmological Model, some of which I attended virtually. In that post I mentioned that Wendy Freedman gave a talk related to the ongoing issue of the Hubble Tension, i.e. the discrepancy between different types of measurement of the Hubble Constant, usually characterized as local measurements (using stellar distance indicators) and larger-scale measurements (chiefly Planck). There are quite a few posts about this issue on this blog. Anyway, Wendy Freedman mention in her talk that her latest work on stellar distances suggested a value of 69.1 ± km s-1 Mpc-1, which reduces the tension with Planck significantly. At the time, however, there was no paper explaining how this number was derived.

Yesterday there appeared on arXiv a preprint by Freedman et al. which summarizes the recent results. The abstract is here:

We present the latest results from the Chicago Carnegie Hubble Program ( CCHP) to measure the Hubble constant using data from the James Webb Space Telescope (JWST). This program is based upon three independent methods: (1) Tip of the Red Giant Branch (TRGB) stars, (2) JAGB (J-Region Asymptotic Giant Branch) stars, and (3) Cepheids. Our program includes 10 nearby galaxies, each hosting Type Ia supernovae (SNe Ia), suitable for measuring the Hubble constant (H0). It also includes NGC 4258, which has a geometric distance, setting the zero point for all three methods. The JWST observations have significantly higher signal-to-noise and finer angular resolution than previous observations with the Hubble Space Telescope (HST). We find three independent values of H0 = 69.85 ± 1.75 (stat) ± 1.54 (sys) for the TRGB, H0 = 67.96 ± 1.85 (stat) ± 1.90 (sys) km s-1 Mpc-1 for the JAGB, and H0 = 72.05 ± 1.86 (stat) ± 3.10 (sys) for Cepheids. Tying into SNe Ia, and combining these methods adopting a flat prior, yields our current estimate of H0 = 69.96 ± 1.05 (stat) ± 1.12 (sys) km s-1 Mpc-1. The distances measured using the TRGB and the JAGB method agree at the 1% level, but differ from the Cepheid distances at the 2.5-4% level. The value of H0 based on these two methods with JWST data alone is H0 = 69.03 ± 1.75 (total error) km s-1 Mpc-1. These numbers are consistent with the current standard ΛCDM model, without the need for the inclusion of additional new physics. Future JWST data will be required to increase the precision and accuracy of the local distance scale.

You can read the full paper on arXiv here. A summary of the summary is that of the three methods they use, two give lower values of the Hubble constant and one (Cepheids) gives a higher value but with larger errors. The number quoted in the Royal Society talk was presumably preliminary as it doesn’t match any of the numbers in the abstract, but the point remains.

You can see the reduction in scatter in the new JWST measurements in this Figure (old on the left and new on the right).

On the face of it, these results suggest that the Hubble tension is greatly reduced. I am sure, however, that advocates of a higher value will have been preparing their ripostes and it’s just a matter of time before they arrive on the arXiv too!

https://telescoper.blog/2024/08/14/hubble-tension-reduced/

#arXiv240806153 #HubbleConstant #HubbleTension #JWST #WendyFreedman