{"title":"Yano-Schrödinger hyperfluid: Cosmological implications","authors":"Himanshu Chaudhary , Saddam Hussain","doi":"10.1016/j.jheap.2025.100447","DOIUrl":null,"url":null,"abstract":"<div><div>Perfect cosmological hyperfluids generalize the concept of a perfect fluid within the framework of metric affine gravity. These hyperfluids encode the microstructure of matter including shear, dilation, and spin via the hypermomentum tensor. In this paper, we focus on the observational constraints of the recently introduced Yano-Schrödinger hyperfluid, which sources a special type of nonmetricity, that preserves the lengths of vectors under autoparallel transport. We propose a model in which the effective nonmetricity contributions to pressure and matter density are related linearly as <span><math><msub><mrow><mi>p</mi></mrow><mrow><mtext>eff</mtext></mrow></msub><mo>=</mo><mi>ω</mi><msub><mrow><mi>ρ</mi></mrow><mrow><mtext>eff</mtext></mrow></msub></math></span>. This assumption allows for a straightforward parameterization of deviations from standard cosmological behavior while maintaining analytical tractability. To constrain the effective equation of state parameter <em>ω</em>, we perform a Bayesian parameter estimation using Nested Sampling, implemented via the <span>PyPolyChord</span> library. We use Baryon Acoustic Oscillation measurements from the Dark Energy Spectroscopic Instrument (DESI) Data Release 2 (DR2), along with Type Ia supernova and Cosmic Chronometer data. In our analysis, we treat <span><math><msub><mrow><mi>r</mi></mrow><mrow><mi>d</mi></mrow></msub></math></span> as a free parameter, enabling late-time data to extract posterior distributions for the Hubble constant (<span><math><msub><mrow><mi>H</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span>) and the sound horizon (<span><math><msub><mrow><mi>r</mi></mrow><mrow><mi>d</mi></mrow></msub></math></span>), along with the corresponding model parameters. Our results yield <span><math><msub><mrow><mi>H</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>=</mo><mn>67.4</mn><mo>±</mo><mn>4.0</mn></math></span> km s<sup>−1</sup> Mpc<sup>−1</sup> and <span><math><msub><mrow><mi>r</mi></mrow><mrow><mi>d</mi></mrow></msub><mo>=</mo><mn>148.8</mn><mo>±</mo><mn>7.4</mn></math></span> Mpc, with <span><math><mi>ω</mi><mo>=</mo><mo>−</mo><mn>0.488</mn></math></span>. Finally, we use the logarithm of the Bayes factor to compare different Yano-Schrödinger model against the ΛCDM model. We find that the LESC model provides a better fit to the data, suggesting that modifications to metric-affine gravity could offer viable alternatives to the standard cosmological paradigm.</div></div>","PeriodicalId":54265,"journal":{"name":"Journal of High Energy Astrophysics","volume":"49 ","pages":"Article 100447"},"PeriodicalIF":10.5000,"publicationDate":"2025-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of High Energy Astrophysics","FirstCategoryId":"101","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2214404825001284","RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ASTRONOMY & ASTROPHYSICS","Score":null,"Total":0}
引用次数: 0
Abstract
Perfect cosmological hyperfluids generalize the concept of a perfect fluid within the framework of metric affine gravity. These hyperfluids encode the microstructure of matter including shear, dilation, and spin via the hypermomentum tensor. In this paper, we focus on the observational constraints of the recently introduced Yano-Schrödinger hyperfluid, which sources a special type of nonmetricity, that preserves the lengths of vectors under autoparallel transport. We propose a model in which the effective nonmetricity contributions to pressure and matter density are related linearly as . This assumption allows for a straightforward parameterization of deviations from standard cosmological behavior while maintaining analytical tractability. To constrain the effective equation of state parameter ω, we perform a Bayesian parameter estimation using Nested Sampling, implemented via the PyPolyChord library. We use Baryon Acoustic Oscillation measurements from the Dark Energy Spectroscopic Instrument (DESI) Data Release 2 (DR2), along with Type Ia supernova and Cosmic Chronometer data. In our analysis, we treat as a free parameter, enabling late-time data to extract posterior distributions for the Hubble constant () and the sound horizon (), along with the corresponding model parameters. Our results yield km s−1 Mpc−1 and Mpc, with . Finally, we use the logarithm of the Bayes factor to compare different Yano-Schrödinger model against the ΛCDM model. We find that the LESC model provides a better fit to the data, suggesting that modifications to metric-affine gravity could offer viable alternatives to the standard cosmological paradigm.
期刊介绍:
The journal welcomes manuscripts on theoretical models, simulations, and observations of highly energetic astrophysical objects both in our Galaxy and beyond. Among those, black holes at all scales, neutron stars, pulsars and their nebula, binaries, novae and supernovae, their remnants, active galaxies, and clusters are just a few examples. The journal will consider research across the whole electromagnetic spectrum, as well as research using various messengers, such as gravitational waves or neutrinos. Effects of high-energy phenomena on cosmology and star-formation, results from dedicated surveys expanding the knowledge of extreme environments, and astrophysical implications of dark matter are also welcomed topics.