发表机构
Università di Bologna; Istituto Nazionale di Astrofisica - Istituto di Radioastronomia (IRA); INAF – Osservatorio di Astrofisica e Scienza dello Spazio di Bologna; University of Cape Town; Zentrum für Astronomie, Universität Heidelberg; Université Paris-Saclay; Université Paris Cité; CEA; CNRS（博洛尼亚大学; 意大利国家天体物理研究所无线电天文研究所; 意大利国家天体物理研究所博洛尼亚天体物理与空间科学观测站; 开普敦大学; 海德堡大学天文中心; 巴黎萨克雷大学; 巴黎西岱大学; 法国原子能及替代能源委员会; 法国国家科学研究中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究结合VLA-COSMOS 3 GHz大项目与COSMOS-Web星表，发现z=3.5以来致密环境可增强射电AGN触发，星系群中射电AGN的空间密度和占比均高于场星系，且触发机制或在z~1.5处发生转变。
AI 中文摘要
射电活动星系核（AGN）是超大质量黑洞动力学反馈的关键示踪物。尽管其触发机制对宿主恒星质量的依赖已为人熟知，但宇宙时标内大尺度环境的影响却鲜为人知。本研究探讨环境在触发射电AGN活动中的作用，同时研究其对恒星质量（$10 \rm \text{[M}_{\text{\textodot}}\text{]} \text{≤} \text{log} \text{M}_{\text{*}} \text{≤} 11.4$）、射电光度（$22 \rm \text{[W Hz}^{-1}\text{]} \text{≤} \text{log} \text{L}_{1.4} \text{≤} 26$）和红移（$0.1 \text{≤} z \text{≤} 3.5$）的依赖关系。我们将VLA-COSMOS 3 GHz大项目与COSMOS-Web星系及星系群星表结合，从总计20203个星系和1678个星系群中选取射电过量AGN，分别构建星系群（124个射电AGN）和场星系（405个射电AGN）的射电光度函数（RLF）及射电AGN占比。我们拟合RLF以推导不同环境下射电AGN的宇宙演化，并提供射电AGN占比作为环境、$\text{M}_{\text{*}}$、$\text{L}_{1.4}$和z的函数的新参数化描述。除证实星系群和场星系中射电AGN占比与宿主$\text{M}_{\text{*}}$存在已知正相关外，更重要的是我们发现：在固定恒星质量下，星系群中射电AGN的空间密度比场星系增强3-30倍，射电AGN占比增强2倍；这种增强还与$\text{M}_{\text{*}}$、$\text{L}_{1.4}$和z相关。此外，在所有红移区间内，射电AGN占比在$r \text{≤} 0.2\text{R}_{200}$范围内达到峰值。总体而言，致密环境对射电AGN触发的增强作用至少延伸至z=3.5。我们提出，射电AGN活动的主导触发机制可能在z~1.5附近存在转变，这或许与低红移时星系群核心的群内介质有关，而在更早宇宙时则与并合和结构增长相关。
英文摘要
Radio active galactic nuclei (AGN) are key tracers of kinetic feedback from supermassive black holes. Although the dependence of their triggering on host stellar mass is well known, the impact of the large-scale environment across cosmic time is poorly understood. We investigate the role of the environment in triggering radio AGN activity, while also studying the dependence on stellar mass ($10\leq\log M_{\ast}\,{\rm [M_{\odot}]}\leq11.4$), radio luminosity ($22\leq\log L_{1.4}\,{\rm [W\,Hz^{-1}]}\leq26$), and redshift ($0.1\leq z \leq 3.5$). We combine the VLA-COSMOS 3 GHz Large Project with the COSMOS-Web galaxy and group catalogs, selecting radio-excess AGN and building radio luminosity functions (RLF) and radio AGN fractions separately for sources in galaxy groups (124 radio AGN) and in the field (405 radio AGN), out of the total of 20203 galaxies and 1678 galaxy groups. We fit the RLF to derive the cosmic evolution of radio AGN in different environments, and we provide a new parametric description of the radio AGN fractions as a function of environment, $M_{\ast}$, $L_{1.4}$, and z. Besides confirming the known positive correlation of radio AGN fraction with host $M_{\ast}$ in both groups and in the field, more importantly we find that the activation of a radio AGN in groups is enhanced relative to the field by a factor of 3--30 in space density and of 2 in radio AGN fraction at fixed stellar mass; the enhancement is also a function of $M_{\ast}$, $L_{1.4}$, and z. Furthermore, in all z bins, the radio AGN fractions peak within $r \leq 0.2R_{200}$. Overall, dense environments enhance radio AGN triggering out to at least z=3.5. We suggest the existence of a possible transition in the dominant triggering mechanism of radio AGN activity around z~1.5, potentially related to the intragroup medium in the core of groups at lower z and to merger and structure growth at earlier cosmic times.
CommentsUnder review for Astronomy & Astrophysics (referee report received)
