A redefinition of the halo boundary leads to a simple yet accurate halo model of large-scale structure. Issue 1 (10th May 2021)

• Record Type: Journal Article
• Authors: García, Rafael; Rozo, Eduardo; Becker, Matthew R; More, Surhud
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 505:Issue 1(2021)
• Page Start: 1195
• Page End: 1205
• Publication Date: 2021-05-10
• Subjects: dark matter -- large-scale structure of Universe -- cosmology: theory; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stab1317
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We present a model for the halo–mass 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 scale-independent bias parameter. However, our model exhibits scale-dependent biasing due to the impact of halo-exclusion, the use of a 'soft' (i.e. not infinitely sharp) halo boundary, and differences in the one halo term contributions to ξhm and ξmm . These features naturally lead us to a redefinition of the halo boundary that lies at the 'by eye' transition radius from the one-halo to the two-halo term in the halo–mass correlation function. When adopting our proposed definition, our model succeeds in describing the halo–mass 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 Press–Schechter mass function with δsc = 1.449 ± 0.004. The clustering bias parameter is offset from the standard background-split 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.