Archive for cosmic tension

Weekly Update from the Open Journal of Astrophysics – 22/02/2025

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , , , , , , , , , , , , , , , on February 22, 2025 by telescoper

It’s Saturday morning again so it’s time for an update of papers published at the Open Journal of Astrophysics. Things have picked up a bit after a quiet couple of weeks. Since the last update we have published four new papers which brings the number in Volume 8 (2025) up to 18 and the total so far published by OJAp up to 253.

In chronological order of publication, the four papers published this week, with their overlays, are as follows. You can click on the images of the overlays to make them larger should you wish to do so.

The first paper to report is in fact our 250th paper:  “Untangling Magellanic Streams” by Dennis Zaritsky (Steward Observatory), Vedant Chandra (Harvard), Charlie Conroy (Harvard), Ana Bonaca (Carnegie Observatories), Phillip A. Cargile (Harvard), and Rohan P. Naidu (MIT), all based in the USA. This paper is in the folder marked Astrophysics of Galaxies and it reports on spectroscopic study aimed at teasing out the stellar populations of different strands of the Magellanic Stream. It was published on Tuesday 18th February 2025. Here is the overlay:

You can read the officially accepted version of this paper on arXiv here.

The second paper of the week  is “Compressed ‘CMB-lite’ Likelihoods Using Automatic Differentiation” by Lennart Balkenhol (Institut d’Astrophysique de Paris, France) which was one of two papers published on Wednesday 19th February. It appears in the folder Cosmology and Nongalactic Astrophysics and it describes an implementation of the CMB-lite framework relying on automatic differentiation to reduce the computational cost of the lite likelihood construction.  The overlay is here:

You can find the officially accepted version of this paper on arXiv here.

The next paper, also published on Wednesday 19th February in the folder Cosmology and Nongalactic Astrophysics is “Bayesian distances for quantifying tensions in cosmological inference and the surprise statistic” by Benedikt Schosser (Heidelberg, Germany), Pedro Riba Mello & Miguel Quartin (Rio de Janeiro, Brazil) and Bjoern Malte Schaefer (Heidelberg).  It presents a discussion of statistical divergences applied to posterior distributions following from different data sets and their use in quantifying discrepancies or tensions.

Here is the overlay:

The official published version can be found on the arXiv here.

Finally in this batch we have “Precise and Accurate Mass and Radius Measurements of Fifteen Galactic Red Giants in Detached Eclipsing Binaries” by Dominick M. Rowan,  Krzysztof Z. Stanek,  Christopher S. Kochanek & Todd A. Thompson (Ohio State University), Tharindu Jayasinghe (independent researcher),  Jacqueline Blaum (UC Berkeley),  Benjamin J. Fulton (NASA/Caltech),  Ilya Ilyin (AIP Potsdam, Germany),  Howard Isaacson, Natalie LeBaron  &  Jessica R. Lu (UC Berkeley), and  David V. Martin (Tufts University, USA).  This paper was published on Thursday 20th February 2025 in the folder Solar and Stellar Astrophysics and it presents a compilation of mass and readius measurements of red giant stars obtained using spectroscopic measurements together with light curves and the eclipsing binary models obtained using PHOEBE.

The overlay is here:

You can find the “final” version on arXiv here.

That’s all for this week. I’ll do another update next Saturday.

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More from the Dark Energy Survey

Posted in Astrohype, The Universe and Stuff with tags , , , , , , on May 28, 2021 by telescoper

To much media interest the Dark Energy Survey team yesterday released 11 new papers based on the analysis of their 3-year data. You can find the papers together with short descriptions here. There’s even a little video about the Dark Energy Survey here:

The official press release summarizes the results as follows:

Scientists measured that the way matter is distributed throughout the universe is consistent with predictions in the standard cosmological model, the best current model of the universe.

This contrasts a bit with the BBC’s version:

The results are a surprise because they show that it is slightly smoother and more spread out than the current best theories predict.

The observation appears to stray from Einstein’s theory of general relativity – posing a conundrum for researchers.

The reason for this appears to be that the BBC story focusses on the weak lensing paper (found here; I’ll add a link to the arXiv version if and when it appears there). The abstract is here:

The parameter S8 is a (slightly) rescaled version of the more familiar parameter σ8  – which quantifies the matter-density fluctuations on a scale of 8 h-1 Mpc – as defined in the abstract; cosmic shear is particularly sensitive to this parameter.

The key figure showing the alleged “tension” with Planck is here:

The companion paper referred to in the above abstract (found here has an abstract that concludes with the words (my emphasis).

We find a 2.3σ difference between our S8 result and that of Planck (2018), indicating no statistically significant tension, and additionally find our results to be in qualitative agreement with current weak lensing surveys (KiDS-1000 and HSC).

So, although certain people have decided to hype up a statistically insignificant l discrepancy, everything basically fits the standard model…

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