Observational constraints on phenomenological emergent dark energy and barotropic dark matter characterized by a constant equation of state parameter

Abstract

While cold dark matter is widely supported by a range of cosmological observations, it encounters several difficulties at smaller scales. These issues have prompted the investigation of various alternative dark matter candidates, leaving the question "What is dark matter?" still open. In this work, we propose a new cosmological model that considers dark matter as a barotropic fluid with a constant equation of state parameter and interprets dark energy as the phenomenological emergent dark energy rather than a cosmological constant. We then place constraints on our new model using the Planck 2018 Cosmic Microwave Background (CMB) anisotropy measurements, Baryon Acoustic Oscillation (BAO) measurements from the Dark Energy Spectroscopic Instrument (DESI), the Pantheon Plus (PP) compilation of Type Ia supernovae (Ia SNe), and the Redshift Space Distortions (RSD) data from Gold2018. The results show statistically significant signal for positive dark matter equation of state and square of sound speed $w_{\mathrm{dm}}=c_{\mathrm{s},\mathrm{dm}}^2$ ($10^7{w}_{\mathrm{dm}}$ = $4.0_{-2.3}^{+2.5}$ at the 95\% confidence level) for the data combination CMB+DESI+PP+RSD. However, Bayesian evidence indicates that this data combination favors the $\Lambda$CDM model with very strong evidence.

14 pages, 2 figures, published on Research in Astronomy and Astrophysics

References in corpus (11)

• DESI 2024 VI: Cosmological Constraints from the Measurements of Baryon Acoustic Oscillations
• The Pantheon+ Analysis: The Full Dataset and Light-Curve Release
• The Clustering of the SDSS Main Galaxy Sample II: Mock galaxy catalogues and a measurement of the growth of structure from Redshift Space Distortions at $z=0.15$
• DESI 2024 III: Baryon Acoustic Oscillations from Galaxies and Quasars
• DESI 2024 IV: Baryon Acoustic Oscillations from the Lyman Alpha Forest
• Growth rate of cosmological perturbations at z ~ 0.1 from a new observational test
• Cosmological Simulations of Decaying Dark Matter: Implications for Small-scale Structure of Dark Matter Halos
• Cosmological bounds on the equation of state of dark matter
• No-go guide for late-time solutions to the Hubble tension: Matter perturbations
• IWDM: The fate of an interacting non-cold dark matter $-$ vacuum scenario
• No-go guide for the Hubble tension: late-time or local-scale new physics

Cited by in corpus (1)

• Revisiting the phenomenologically emergent dark energy model: is non-zero equation of state of dark matter favored by DESI DR2?