{"about":{"site":"https://codewithpapers.app","non_affiliation":"Code with Papers and Syntology are not affiliated with, endorsed by, or sponsored by Papers with Code, Meta, or the pwc-archive mirror.","licence":"CC BY-SA 4.0","licence_url":"https://creativecommons.org/licenses/by-sa/4.0/legalcode","attribution":"https://codewithpapers.app/attribution","modified":"archive material modified by Syntology; see the attribution page"},"url":"/paper/assembly-bias-in-the-local-png-halo-bias-and","title":"Assembly bias in the local PNG halo bias and its implication for $f_{\\rm NL}$ constraints","arxiv_id":"2209.07251","date":"2022-09-15","proceeding":null,"authors":["Titouan Lazeyras","Alexandre Barreira","Fabian Schmidt","Vincent Desjacques"],"abstract":"We use $N$-body simulations to study halo assembly bias (i.e., the dependence of halo clustering on properties beyond total mass) in the density and primordial non-Gaussianity (PNG) linear bias parameters $b_1$ and $b_\\phi$, respectively. We consider concentration, spin and sphericity as secondary halo properties, for which we find a clear detection of assembly bias for $b_1$ and $b_\\phi$. At fixed total mass, halo spin and sphericity impact $b_1$ and $b_\\phi$ in a similar manner, roughly preserving the shape of the linear $b_\\phi(b_1)$ relation satisfied by the global halo population. Halo concentration, however, drives $b_1$ and $b_\\phi$ in opposite directions. This induces significant changes to the $b_\\phi(b_1)$ relation, with higher concentration halos having higher amplitude of $b_\\phi(b_1)$. For $z=0.5$ and $b_1 \\approx 2$ in particular, the population comprising either all halos, those with the $33\\%$ lowest or those with the $33\\%$ highest concentrations have a PNG bias of $b_\\phi \\approx 3$, $b_\\phi \\approx -1$ and $b_\\phi \\approx 9$, respectively. Varying the halo concentration can make $b_\\phi$ very small and even change its sign. These results have important ramifications for galaxy clustering constraints of the local PNG parameter $f_{\\rm NL}$ that assume fixed forms for the $b_\\phi(b_1)$ relation. We illustrate the significant impact of halo assembly bias in actual data using the BOSS DR12 galaxy power spectrum: assuming that BOSS galaxies are representative of all halos, the $33\\%$ lowest or the $33\\%$ highest concentration halos yields $\\sigma_{f_{\\rm NL}} = 44, 165, 19$, respectively. Our results suggest taking host halo concentration into account in galaxy selection strategies to maximize the signal-to-noise on $f_{\\rm NL}$. They also motivate more simulation-based efforts to study the $b_\\phi(b_1)$ relation of halos and galaxies.","url_abs":"https://arxiv.org/abs/2209.07251v2","url_pdf":"https://arxiv.org/pdf/2209.07251v2.pdf","source":{"archive":"pwc-archive (Hugging Face), CC BY-SA 4.0","snapshot":"2025-07-28","licence_url":"https://creativecommons.org/licenses/by-sa/4.0/legalcode","row_kind":"links_only","authors_date_abstract":"arXiv metadata, CC0 1.0 (https://info.arxiv.org/help/license), from the Kaggle arXiv metadata snapshot of 2026-09-12"},"code_links":[{"paper_slug":"assembly-bias-in-the-local-png-halo-bias-and","repo_url":"https://github.com/oliverphilcox/spectra-without-windows","is_official":1,"mentioned_in_paper":1,"mentioned_in_github":0,"framework":"none","reach":{"status":"ok","spdx":"MIT"}}],"tasks":[],"methods":[],"datasets_introduced":[],"methods_introduced":[],"results":[],"syntology":{"syntology_url":null,"atlas_url":null,"mcp":null,"developers":"https://syntology.ai/developers"},"arxiv_metadata":null,"syntology_extracted_results":null}