19 January 2022Séminaire – Gauri Sharma (University of Western Cape)

© 2022 Observatoire Astronomique de Strasbourg | Webdesign et développement Alchimy.

Observational Evidence of Evolving Dark Matter Halos with cosmic time

Abstract

In the late 1970s, Vera Rubin showed that flat rotation curves are ubiquitous in local Star-forming Galaxies (SFGs) and 
concluded that “galaxies are surrounded by an invisible matter, the so-called dark matter halo, that extends much farther
than their visible matter”. However, recent observations, in 2017, of high-redshift SFGs show declining Rotation Curves
(RCs), and thus questioning the “faith of the dark matter halos” back in time. I will present a study of z~1 SFGs, in which I have tested and applied several cutting-edge techniques capable of dealing with
the observational and physical conditions that are commonly encountered in high-redshift observations. My work shows that:
  • RCs of z~1 SFGs are flat and similar to their local counterparts.
  • SFGs at z~1 are dark matter dominated till outer disks (∼ 5 to 15 kpc).
  • Density profile of dark matter halos evolve between z ≈ 0 and z ∼ 1.
I will briefly discuss the above results, and present an interesting work that observationally measures the dark matter response to the 
baryonic (feedback) processes. I will show the empirical relation between the observable properties of dark and luminous matter,
which can be verified with current and future surveys. In future, a comparison of this work with simulations can specify the role
of baryonic (feedback) processes in galaxy evolution, as well as constraints on the mass and cross section of a potential dark matter particle.