Separate Universe calibration of the dependence of halo bias on cosmic web anisotropy. (arXiv:2007.03711v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Ramakrishnan_S/0/1/0/all/0/1">Sujatha Ramakrishnan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Paranjape_A/0/1/0/all/0/1">Aseem Paranjape</a>
We use the Separate Universe technique to calibrate the dependence of linear
and quadratic halo bias $b_1$ and $b_2$ on the local cosmic web environment of
dark matter haloes. We do this by measuring the response of halo abundances at
fixed mass and cosmic web tidal anisotropy $alpha$ to an infinite wavelength
initial perturbation. We augment our measurements with an analytical framework
developed in earlier work which exploits the near-Lognormal shape of the
distribution of $alpha$ and results in very high precision calibrations. We
present convenient fitting functions for the dependence of $b_1$ and $b_2$ on
$alpha$ over a wide range of halo mass for redshifts $0leq zleq1$. Our
calibration of $b_2(alpha)$ is the first demonstration to date of the
dependence of non-linear bias on the local web environment. Motivated by
previous results which showed that $alpha$ is the primary indicator of halo
assembly bias for a number of halo properties beyond halo mass, we then extend
our analytical framework to accommodate the dependence of $b_1$ and $b_2$ on
any such secondary property which has, or can be monotonically transformed to
have, a Gaussian distribution. We demonstrate this technique for the specific
case of halo concentration, finding good agreement with previous results. Our
calibrations will be useful for a variety of halo model analyses focusing on
galaxy assembly bias, as well as analytical forecasts of the potential for
using $alpha$ as a segregating variable in multi-tracer analyses.
We use the Separate Universe technique to calibrate the dependence of linear
and quadratic halo bias $b_1$ and $b_2$ on the local cosmic web environment of
dark matter haloes. We do this by measuring the response of halo abundances at
fixed mass and cosmic web tidal anisotropy $alpha$ to an infinite wavelength
initial perturbation. We augment our measurements with an analytical framework
developed in earlier work which exploits the near-Lognormal shape of the
distribution of $alpha$ and results in very high precision calibrations. We
present convenient fitting functions for the dependence of $b_1$ and $b_2$ on
$alpha$ over a wide range of halo mass for redshifts $0leq zleq1$. Our
calibration of $b_2(alpha)$ is the first demonstration to date of the
dependence of non-linear bias on the local web environment. Motivated by
previous results which showed that $alpha$ is the primary indicator of halo
assembly bias for a number of halo properties beyond halo mass, we then extend
our analytical framework to accommodate the dependence of $b_1$ and $b_2$ on
any such secondary property which has, or can be monotonically transformed to
have, a Gaussian distribution. We demonstrate this technique for the specific
case of halo concentration, finding good agreement with previous results. Our
calibrations will be useful for a variety of halo model analyses focusing on
galaxy assembly bias, as well as analytical forecasts of the potential for
using $alpha$ as a segregating variable in multi-tracer analyses.
http://arxiv.org/icons/sfx.gif
