A redefinition of the halo boundary leads to a simple yet accurate halo model of largescale structure
Abstract
We present a model for the halomass correlation function that explicitly incorporates halo exclusion and allows for a redefinition of the halo boundary in a flexible way. We assume that haloes trace mass in a way that can be described using a single scaleindependent bias parameter. However, our model exhibits scaledependent biasing due to the impact of haloexclusion, the use of a 'soft' (i.e. not infinitely sharp) halo boundary, and differences in the one halo term contributions to ξ_{hm} and ξ_{mm}. These features naturally lead us to a redefinition of the halo boundary that lies at the 'by eye' transition radius from the onehalo to the twohalo term in the halomass correlation function. When adopting our proposed definition, our model succeeds in describing the halomass correlation function with $\approx 2{{\ \rm per\ cent}}$ residuals over the radial range 0.1 h^{1} Mpc < r < 80 h^{1} Mpc, and for halo masses in the range 10^{13} h^{1} M_{⊙} < M < 10^{15} h^{1} M_{⊙}. Our proposed halo boundary is related to the splashback radius by a roughly constant multiplicative factor. Taking the 87 percentile as reference we find r_{t}/R_{sp} ≈ 1.3. Surprisingly, our proposed definition results in halo abundances that are well described by the PressSchechter mass function with δ_{sc} = 1.449 ± 0.004. The clustering bias parameter is offset from the standard backgroundsplit prediction by $\approx 10{{\ \rm per\ cent}}\!\!15{{\ \rm per\ cent}}$. This level of agreement is comparable to that achieved with more standard halo definitions.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 July 2021
 DOI:
 10.1093/mnras/stab1317
 arXiv:
 arXiv:2006.12751
 Bibcode:
 2021MNRAS.505.1195G
 Keywords:

 dark matter;
 largescale structure of Universe;
 cosmology: theory;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 12 pages, 5 figures