Understanding higherorder nonlocal halo bias at large scales by combining the power spectrum with the bispectrum
Abstract
Understanding the relation between underlying matter distribution and biased tracers such as galaxies or dark matter halos is essential to extract cosmological information from ongoing or future galaxy redshift surveys. At sufficiently large scales such as the baryon acoustic oscillation (BAO) scale, a standard approach for the bias problem on the basis of the perturbation theory (PT) is to assume the "local bias" model in which the density field of biased tracers is deterministically expanded in terms of matter density field at the same position. The higherorder bias parameters are then determined by combining the power spectrum with higherorder statistics such as the bispectrum. As is pointed out by recent studies, however, nonlinear gravitational evolution naturally induces nonlocal bias terms even if initially starting only with purely local bias. As a matter of fact, previous works showed that the secondorder nonlocal bias term, which corresponds to the gravitational tidal field, is important to explain the characteristic scaledependence of the bispectrum. In this paper we extend the nonlocal bias term up to third order, and investigate whether the PTbased model including nonlocal bias terms can simultaneously explain the power spectrum and the bispectrum of simulated halos in N body simulations. The bias renormalization procedure ensures that only one additional term is necessary to be introduced to the power spectrum as a nexttoleading order correction, even if thirdorder nonlocal bias terms are taken into account. We show that the power spectrum, including density and momentum, and the bispectrum between halo and matter in N body simulations can be simultaneously well explained by the model including up to thirdorder nonlocal bias terms at k ≲0.1 h /Mpc . Also, the results are in a good agreement with theoretical predictions of a simple coevolution picture, although the agreement is not perfect. These trend can be found for a wide range of halo mass, 0.7 ≲M_{halo}[1 0^{13}M_{⊙}/h ]≲20 at various redshifts, 0 ≤z ≤1 . These demonstrations clearly show a failure of the local bias model even at such large scales, and we conclude that nonlocal bias terms should be consistently included in order to accurately model statistics of halos.
 Publication:

Physical Review D
 Pub Date:
 December 2014
 DOI:
 10.1103/PhysRevD.90.123522
 arXiv:
 arXiv:1405.1447
 Bibcode:
 2014PhRvD..90l3522S
 Keywords:

 98.65.Dx;
 95.35.+d;
 98.80.Es;
 Superclusters;
 largescale structure of the Universe;
 Dark matter;
 Observational cosmology;
 Astrophysics  Cosmology and Nongalactic Astrophysics;
 Astrophysics  Astrophysics of Galaxies
 EPrint:
 29 pages, matched to the accepted version