{"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/properties-and-evolution-of-dual-and-offset","title":"Properties and Evolution of Dual and Offset AGN in the ASTRID Simulation at $z \\sim 2$","arxiv_id":"2208.04970","date":"2022-08-09","proceeding":null,"authors":["Nianyi Chen","Tiziana Di Matteo","Yueying Ni","Michael Tremmel","Colin DeGraf","Yue Shen","A. Miguel Holgado","Simeon Bird","Rupert Croft","Yu Feng"],"abstract":"We examine the dual (both BHs active) and offset (one BH active) AGN population (comprising $\\sim$ 2000 pairs at $0.5\\,\\text{kpc}\\lesssim\\Delta r<30\\,\\text{kpc}$) at $z=2\\sim3$ in the ASTRID simulation covering (360 cMpc)${^3}$. The dual (offset) AGN make up $3.0(2.2)\\%$ of all AGN at $z=2$. The dual fraction is roughly constant while the offset fraction increases by a factor of ten from $z=4\\sim2$. Compared with the full AGN population, duals are characterized by a low $M_\\text{BH}/M_*$ ratio, a high specific star-formation rate (sSFR) of $\\sim 1\\,\\text{Gyr}^{-1}$, and a high Eddington ratio ($\\sim 0.05$, double that of single AGN). The dual AGN are formed in major galaxy mergers (typically involving $M_\\text{halo}<10^{13}\\,M_\\odot$), with BHs that have similar masses. At small separations (when their host galaxies are in the late phase of the merger) duals become $2\\sim8$ times brighter (albeit more obscured) than at larger separations. $80\\%$ of these bright, close duals merge in the simulation within $\\sim500\\,\\text{Myrs}$. Notably, the initially less-massive BH in duals frequently becomes the brighter AGN during the galaxy merger. In offset AGN, the active BH is typically $\\gtrsim 10$ times more massive than its non-active counterpart and than most BHs in duals. Offsets are predominantly formed in minor galaxy mergers with the active BH residing in the center of massive halos ($ M_\\text{ halo}\\sim 10^{13-14}\\,M_\\odot$). In these deep potentials, gas stripping is common and the secondary quickly deactivates. The stripping also leads to inefficient orbital decay amongst offsets, which stall at $\\Delta r\\sim5\\,\\text{kpc}$ for a few hundred Myrs.","url_abs":"https://arxiv.org/abs/2208.04970v1","url_pdf":"https://arxiv.org/pdf/2208.04970v1.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":"properties-and-evolution-of-dual-and-offset","repo_url":"https://github.com/MP-Gadget/MP-Gadget","is_official":1,"mentioned_in_paper":1,"mentioned_in_github":0,"framework":"none","reach":{"status":"ok","spdx":"NOASSERTION"}}],"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}