Scaledependent bias and bispectrum in neutrino separate universe simulations
Abstract
Cosmic background neutrinos have a large velocity dispersion, which causes the evolution of longwavelength density perturbations to depend on scale. This scaledependent growth leads to the wellknown suppression in the linear theory matter power spectrum that is used to probe neutrino mass. In this paper, we study the impact of longwavelength density perturbations on smallscale structure formation. By performing separate universe simulations where the longwavelength mode is absorbed into the local expansion, we measure the responses of the cold dark matter (CDM) power spectrum and halo mass function, which correspond to the squeezedlimit bispectrum and halo bias. We find that the scaledependent evolution of the longwavelength modes causes these quantities to depend on scale and provide simple expressions to model them in terms of scale and the amount of massive neutrinos. Importantly, this scaledependent bias reduces the suppression in the linear halo power spectrum due to massive neutrinos by 13% and 26% for objects of bias b ¯=2 and b ¯≫1 , respectively. We demonstrate with high statistical significance that the scaledependent halo bias cannot be modeled by the CDM and neutrino density transfer functions at the time when the halos are identified. This reinforces the importance of the temporal nonlocality of structure formation, especially when the growth is scale dependent.
 Publication:

Physical Review D
 Pub Date:
 June 2018
 DOI:
 10.1103/PhysRevD.97.123526
 arXiv:
 arXiv:1710.01310
 Bibcode:
 2018PhRvD..97l3526C
 Keywords:

 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 24 pages, 18 figures