Shot noise in galaxy clustering: halo model approach and its cosmological implications

by Mr. Dimitry Ginzburg

at Astrophysics and Cosmology Seminar

Wed, 13 Nov 2019, 11:10
Sacta-Rashi Building for Physics (54), room 207


Shot noise is an important ingredient to any measurement or theoretical modeling of discrete tracers of the large scale structure. Recent work has shown that the shot noise in the halo power spectrum becomes increasingly sub-Poissonian at high mass. Interestingly, while the halo model predicts a shot noise power spectrum in qualitative agreement with the data, it leads to an unphysical white noise in the cross halo-matter and matter power spectrum. We show that absorbing all the halo model sources of shot noise into the halo fluctuation field leads to meaningful predictions for the shot noise contributions to halo clustering statistics and remove the unphysical white noise from the cross halo-matter statistics. We show a new class of consistency relations for discrete tracers, which appear to be satisfied by our reformulation of the halo model. We test our theoretical predictions against measurements of halo shot noise bispectra extracted from numerical simulations. Our model reproduces qualitatively the observed sub-Poissonian noise, although it underestimates the magnitude of this effect. Also, we calculate the effect of the uncertainty in the model for the shot noise on parameters which become important on large scales - parameters which appear in red shift surveys due to projection effects and the primordial non-Gaussianity. We use Fisher analysis to compare the systematic error due to the use of a wrong model in those parameters to their statistical errors and we calculate the effect of marginalization over all shot noise values. We compare the measurement significance of those parameters when various numbers of bins is used and we show the optimal division into mass bins when only two bins are considered.

Created on 07-11-2019 by Zitrin, Adi (zitrin)
Updaded on 07-11-2019 by Zitrin, Adi (zitrin)