自红移z~5以来最庞大星系中致密化、淬灭与黑洞增长的相互作用：来自JWST和Chandra数据的见解
Interplay of Compaction, Quenching, and Black Hole Growth in the Most Massive Galaxies since $z\sim5$: Insights from JWST and Chandra Data
浏览论文内容
中文总结 AI 辅助
本研究结合JWST与Chandra数据，追踪z<5的大质量星系演化，发现z~4时的中心致密化伴随多数AGN出现，z~3时由内而外淬灭启动，黑洞增长主要发生于致密化期间，致密核形成标志着相关演化转变。
中文摘要 AI 辅助
致密恒星核的形成被认为标志着大质量星系恒星形成与黑洞增长过程中的一个重要转变。本研究利用詹姆斯·韦布空间望远镜（JWST）近红外成像的空间分辨光谱能量分布（SED）拟合，结合钱德拉（Chandra）X射线数据的叠加分析，追踪了z<5的最庞大星系中的恒星质量累积与平均黑洞吸积过程：在每个红移区间内，以约4.4×10⁻⁵ cMpc⁻³的恒定数密度选取50个最庞大的星系。为了可靠地限制中心恒星种群，研究通过多波段形态分解与SED分析，分离了影响测光的活动星系核（AGN）成分。研究发现，以恒定数密度选取的样本在z~4时呈现出快速中心致密化的演化趋势，此期间中心1千秒差距（kpc）范围内的恒星质量中位数在约4亿年（Myr）内增长了约0.60 dex；在X射线探测到的AGN中，有63%±12%的宿主星系正处于致密化过程中，而在z>4时，既未探测到单个X射线源，也未发现显著的叠加X射线信号，这表明平均而言，大量黑洞增长主要发生在致密化期间，而非致密化之前。致密化之后，在z~3时，中心恒星形成率（sSFR）在约7亿年（Myr）内下降了约1.24 dex，而星系整体的恒星形成率仍保持较高水平，这标志着由内而外淬灭的开始；尽管中心恒星形成受到抑制，但黑洞吸积率仍与总恒星形成率保持耦合。研究结果表明，最庞大星系中致密核的形成标志着由内而外淬灭的开始，以及黑洞与恒星增长比值向增强方向的转变。
英文摘要
The buildup of dense stellar cores is expected to mark an important transition in the star-formation and black-hole growth of massive galaxies. Using spatially resolved spectral energy distribution (SED) fitting of James Webb Space Telescope near-infrared imaging, combined with stacking analysis of Chandra X-ray data, we trace stellar mass buildup and average black hole accretion in the most massive galaxies at $z<5$, selecting 50 most massive galaxies per redshift bin at constant number density of $\sim4.4\times10^{-5}$ cMpc$^{-3}$. To robustly constrain central stellar populations, we separate active galactic nuclei (AGN) components affecting the photometry using multi-band morphological decomposition and SED analysis. We find that the sample selected with constant number density exhibits evolutionary trend of rapid central compaction at $z\sim4$, during which the median central 1 kpc stellar mass increases by $\sim0.60$ dex over $\sim400$ Myr. The majority of X-ray detected AGN ($63\%\pm12\%$) are hosted by galaxies undergoing the compaction, while we find neither individually detected X-ray sources nor a significant stacked X-ray signal at $z>4$, indicating that substantial average black-hole growth emerges primarily during, rather than before, the compaction. Following the compaction, central specific star formation rates (sSFR) decline by $\sim1.24$ dex over $\sim700$ Myr at $z\sim3$ while remaining elevated galaxy-wide, signaling the onset of inside-out quenching. Despite this central suppression, specific black hole accretion rate remains coupled to the total sSFR. Our results suggest that dense-core formation in the most massive galaxies marks the onset of inside-out quenching and a transition toward enhanced black-hole to stellar growth ratio.
