Astro Seminar Series - VIA ZOOM

Wednesday, April 22, 2020 11:30 am - 11:30 am EDT (GMT -04:00)

Andrej Obuljen
Andrej Obuljen is a postdoctoral fellow at the University of Waterloo working with Prof. Will Percival. He has earned his PhD degree at SISSA (Italy). His main research interest is studying the Large-scale Structure of our Universe using either future 21cm Intensity Mapping or upcoming spectroscopic galaxy surveys (e.g. DESI) in order to better constrain main cosmological parameters.

Title and Abstract for Andrej's talk:

Anisotropic assembly bias in theory, simulations and data

Abstract:  Clustering of matter on large scales provides an important source of information on key cosmological parameters. To extract this information we need to understand the relation between the tracers we observe and the underlying matter field. The clustering strength of halos and galaxies on large scales is linearly biased compared to the matter clustering.  This linear bias mainly depends on halo mass and redshifts, though selections based on other scalar halo properties (age, spin, concentration etc.) show additional bias dependences — called assembly bias. Furthermore, non-scalar halo properties: shapes, velocity dispersion and angular momentum, are correlated with the large-scale tidal field. Selection effects that couple to these non-scalar halo properties can produce anisotropic clustering even in real-space and act as a contaminant to redshift-space distortion measurements, through an anisotropic assembly bias (AB).  I will discuss our recent results on studying the halo AB using a large number of numerical simulations.  Then I will present the first observational evidence of the galaxy AB in BOSS DR12 galaxies. Finally, I will show other consequences and future prospects.