Daniel FischerMar 5
The Stochastic Siren - Astrophysical Gravitational-Wave Background Measurements of the #HubbleConstant: https://arxiv.org/abs/2503.01997 -> Illinois and UChicago physicists develop a new method to measure the expansion rate of the universe: https://physics.illinois.edu/news/Hubble-tension-expansion-rate-of-universe
The Stochastic Siren: Astrophysical Gravitational-Wave Background Measurements of the Hubble Constant

We report the first measurement of the Hubble constant $H_0$ using the stochastic gravitational-wave background arising from binary black hole mergers. This astrophysical background is sensitive to the expansion history of the Universe and thus can be used for cosmological parameter inference independently of not only electromagnetic methods, but also gravitational-wave standard siren approaches. We describe the background's cosmological dependence and show how it can be used as a ``stochastic siren'' to measure $H_0$. By analyzing existing resolved binary black hole mergers and the current non-detection of the background, we find that $H_0$ can be measured more accurately relative to using resolved mergers alone. We also note that the stochastic siren may serve a unique role in the Hubble tension in that the lower bound of the $H_0$ measurement would progressively increase with continued non-detection of the background.

arXiv.org
KillBaitMar 1

New Method Uses Gravitational Waves to Improve Measurements of the Universe's Expansion

📰 Original title: A faint cosmic hum could solve the Universe’s expansion mystery

🤖 IA: It's not clickbait ✅
👥 Usuarios: It's not clickbait ✅

View full AI summary: https://killbait.com/en/new-method-uses-gravitational-waves-to-improve-measurements-of-the-universes-expansion/?redirpost=4e6ee84f-05b8-4f2c-ba0b-ad2d64423b1d

#science #gravitationalwaves #universeexpansion #hubbleconstant

New Method Uses Gravitational Waves to Improve Measurements of the Universe’s Expansion

Astronomers have long known that the universe is expanding, but the exact rate of expansion, measured by the Hubble constant, remains a mystery. Multiple methods used to calculate this constant have…

KillBait Archive
Technische Universität MünchenFeb 19

Munich astronomers imaged and modelled an exceptionally rare #supernova that could provide a new, independent way to measure how fast the #universe is expanding: http://go.tum.de/991366 🌌

#hubbleconstant #cosmicexpansion #cosmology #astrophysics

📷C. Saulder

Measuring the expansion of the universe with cosmic fireworks

That the universe is expanding has been known for almost a hundred years now, but how fast? The exact rate of that expansion remains hotly debated,…

universeinthelab_enFeb 19

Join us for the latest lecture of "Wissenschaft für Alle"!
What is the #HubbleConstant and how is it determined? Find out with Andreas Flörs (GSI/FAIR) 🌌
German only.

Online or on site as usual: Wednesday, 25 February 2026, 2 PM

Online event: https://gsi-fair.zoom.us/j/98465545116#success
Meeting-Code: wfa
On site registration: https://indico.gsi.de/event/23430/registrations/7199/
Location: GSI/FAIR #Darmstadt

© NASA, ESA, CSA, STScI
#lecture #science #WissenschaftfürAlle #WfA #particleaccelerator #space

qurlyjoeDec 25
So I’m reading an article in New Scientist about problems nailing down the #HubbleConstant and I thought, if the universe is expanding, as in adding new space where there already is some, why isn’t everything expanding with it? All I can think of is, it’s gravity doing it, keeping localized bits of matter together, from subatomic particles to galaxies in size, essentially fighting an epic, mythic battle against The Expansion. Which side are dark energy & dark matter on?
Daniel PomarèdeNov 12

Prof. Wendy Freedman recognized with 2026 Franklin Institute Award in Physics

Pioneering cosmologist honored for landmark measurements of the Hubble Constant.

https://news.uchicago.edu/story/prof-wendy-freedman-recognized-2026-franklin-institute-award-physics

#Cosmology #WendyFreedman #HubbleConstant #Astronomy #Astrophysics #Astrodon #science #news #UChicago

Prof. Wendy Freedman recognized with 2026 Franklin Institute Award in Physics

Pioneering cosmologist honored for landmark measurements of the Hubble Constant

University of Chicago News
Stephen "The Hammer" MorrisSep 19

My beautiful star charts that I made to map the Universe. Hint: we're in the middle.

Feast your eyes.

#hubbleconstant
#naturaldisasterchannel
#globalwomensheritagefund
#tibees
#MastoArt
#AIDebate
#runnymede

Daniel FischerSep 10, 2025
Carnegie Supernova Project - Fast-Declining Type Ia Supernovae as Cosmological Distance Indicators: https://arxiv.org/abs/2509.07093 -> thread https://x.com/DScol/status/1965783510469546370 -> the #HubbleConstant is ... 75!
Carnegie Supernova Project: Fast-Declining Type Ia Supernovae as Cosmological Distance Indicators

In this paper, the suitability of fast-declining Type Ia supernovae (SNe Ia) as cosmological standard candles is examined utilizing a Hubble Flow sample of 43 of these objects observed by the Carnegie Supernova Project (CSP). We confirm previous suggestions that fast-declining SNe Ia offer a viable method for estimating distances to early-type galaxies when the color-stretch parameter, $s_{BV}$, is used as a measure of the light curve shape. As a test, we employ the Tripp (1998) method, which models the absolute magnitude at maximum as a function of light curve shape and color. We calibrate the sample using 12 distance moduli based on published Infrared Surface Brightness Fluctuations to derive a value of the Hubble constant that is in close agreement with the value found by Uddin et al. (2024), using the same methodology, but with the full sample of CSP SNe Ia. We also develop a new and simple method of estimating the distances of fast decliners only based on their colors at maximum (and not light curve shape) and find that it has a precision similar to the Tripp method. This "Color" technique is a powerful tool that is unique to fast-declining SNe Ia. We show that the colors of the fast decliners at maximum light are strongly affected by photospheric temperature differences and not solely due to dust extinction, and provide a physical rationale for this effect.

arXiv.org
Daniel PomarèdeSep 4, 2025

#Cosmology

The Perfect Host: JWST Cepheid Observations in a Background-Free SN Ia Host Confirm No Bias in Hubble-Constant Measurements

by Adam Riess and co-authors
https://arxiv.org/abs/2509.01667

#HubbleTension #HubbleConstant #Astrodon #science #jwst

Daniel PomarèdeJul 31, 2025

in the #arXiv

Prior-free cosmological parameter estimation of Cosmicflows-4

The analysis suggests a Hubble constant value of 75.8±0.4 km/s /Mpc, exacerbating (or independently confirming) the existing "Hubble Tension".

by Chaimongkol Duangchan and co-authors
https://arxiv.org/abs/2507.22236

#Cosmology #Cosmicflows #HubbleConstant #HubbleTension #Astrophysics #Astrodon #galaxies #physics #science

Prior-free cosmological parameter estimation of Cosmicflows-4

As tracers of the underlying mass distributions, galaxies' peculiar velocities are valuable probes of the Universe, allowing us to measure the Hubble constant or to map the large scale structure and its dynamics. Yet, catalogs of peculiar velocities are noisy, scarce and prone to various interpretation biases. We aim to measure the bulk flow and the Hubble constant directly from the largest available sample of peculiar velocities, and without imposing a cosmological prior on the velocity field. To address these issues, we analyze the Cosmicflows-4 catalog, the most extensive catalog of galaxy peculiar velocities, reaching a redshift $z=0.1$. Specifically, we construct a forward modeling approach assuming only a flat Universe, which reconstructs the radial and bulk flows of the velocity field directly from measurements of peculiar velocities. Our method accurately recovers cosmological parameters within a radius of $120\ \mathrm{Mpc/h}$ that can then be compared with the predictions from $Λ{\rm CDM}$. Apart from a $3σ$ tension with $Λ{\rm CDM}$ on the magnitude around $120\ \mathrm{Mpc/h}$ associated with a $4σ$ tension on the supergalactic $X$ direction, we find a general agreement between the standard model and the observations. Lastly, our analysis suggests a Hubble constant value of approximately $75.8\pm0.4\ \mathrm{km/s/Mpc}$, exacerbating (or independently confirming) the existing ``Hubble tension", however, for the first time accomplished with the largest set of peculiar velocities in existence.

arXiv.org