Testing the warmness of dark matter

Author(s)

Kumar, Suresh ^[1] ; Nunes, Rafael C. ^[2] ; Yadav, Santosh Kumar ^[1]

Affiliation

^[1] BITS Pilani, Dept Math, Pliani Campus, Pilani 333031, Rajasthan - India

^[2] Inst Nacl Pesquisas Espaciais, Div Astrofis, Ave Astronautas 1758, BR-12227010 Sao Jose Dos Campos, SP - Brazil

• Document type: Journal article
• Source: Monthly Notices of the Royal Astronomical Society; v. 490, n. 1, p. 1406-1414, NOV 2019.
• Web of Science Citations: 0

Abstract

Dark matter (DM) as a pressureless perfect fluid provides a good fit of the standard Lambda cold dark matter (Lambda CDM) model to the astrophysical and cosmological data. In this paper, we investigate two extended properties of DM: a possible time dependence of the equation of state of DM via Chevallier-Polarski-Linder parametrization, w(dm) = w(dm0) + w(dm1)(1 - a), and the constant non-null sound speed (c) over cap (2)(s,dm). We analyse these DM properties on top of the base Lambda CDM model by using the data from Planck cosmic microwave background (CMB) temperature and polarization anisotropy, baryonic acoustic oscillations (BAOs), and the local value of the Hubble constant from the Hubble Space Telescope (HST). We find new and robust constraints on the extended free parameters of DM. The most tight constraints are imposed by CMB+BAO data, where the three parameters w(dm0), w(dm1), and (c) over cap (2)(s,dm) are, respectively, constrained to be less than 1.43 x 10(-3), 1.44 x 10(-3), and 1.79 x 10(-6) at 95 per cent CL. All the extended parameters of DM show consistency with zero at 95 per cent CL, indicating no evidence beyond the CDM paradigm. We notice that the extended properties of DM significantly affect several parameters of the base Lambda CDM model. In particular, in all the analyses performed here, we find significantly larger mean values of H-0 and lower mean values of sigma(8) in comparison to the base Lambda CDM model. Thus, the well-known H-0 and sigma(8) tensions might be reconciled in the presence of extended DM parameters within the Lambda CDM framework. Also, we estimate the warmness of DM particles as well as its mass scale, and find a lower bound: similar to 500 eV from our analyses. (AU)

• FAPESP's process: 18/18036-5 - Investigating physical aspects beyond the standard model linked to the themes of dark energy, modified gravity, neutrinos and gravitational waves
• Grantee: Rafael da Costa Nunes
• Support Opportunities: Scholarships in Brazil - Post-Doctoral