标题： 红移 z > 7 星系盘碎裂形成原初星团；揭示詹姆斯韦伯空间望远镜观测到的超紧致星团和超大质量黑洞 显示英文标题

标题： In-situ formation of star clusters at z > 7 via galactic disk fragmentation; shedding light on ultra-compact clusters and overmassive black holes seen by JWST

摘要： 我们研究了位于显著 overdense 区域内的富含气体星系$z > 7$的恒星形成性质，在一个已经超出$10^{12}$乘以$_{\odot}$太阳质量的庞大塌缩晕周围的区域。 我们发现，不仅主星系，连低质量伴星系也迅速形成了尺寸小于 500 pc 的巨大自引力紧凑气体盘，并因引力不稳定性而碎裂成非常巨大的束缚气体团块。 星系团中的恒星形成过程迅速，这些星系团很快演化为紧凑的星团，质量范围在$10^5$-$10^8$ M$_{\odot}$之间，典型的半质量半径为几秒差距，并达到高于$10^5$ M$_{\odot}$ pc$^{-2}$的特征密度。 低质量星系中的星团性质与詹姆斯·韦布空间望远镜（JWST）最近在$z = 10.2$处的透镜宇宙宝石弧系统中发现的性质有惊人的相似之处。 我们提出，由于其极高的恒星密度，中间质量黑洞（IMBH）会在星团内部迅速形成，随后快速下沉并合并，最终到达星系核，轻松成长为一个 $10^7$~M$_{\odot}$质量的超大质量黑洞（SMBH）。 由于星团对星系恒星质量的高比例贡献，在 $20$-$40\%$的范围内，中心的SMBH的质量会超过其寄主星系质量的 $10\%$，这自然解释了詹姆斯·韦布空间望远镜在 $z > 6$处发现的超大质量黑洞。 显示英文摘要

摘要： We investigate the nature of star formation in gas-rich galaxies at $z > 7$ forming in a markedly overdense region, in the whereabouts of a massive virialized halo already exceeding $10^{12}$ M$_{\odot}$. We find that not only the primary galaxy, but also the lower-mass companion galaxies rapidly develop massive self-gravitating compact gas disks, less than 500~pc in size, which undergo fragmentation by gravitational instability into very massive bound clumps. Star formation proceeds fast in the clumps, which quickly turn into compact star clusters with masses in the range $10^5$-$10^8$ M$_{\odot}$ and typical half-mass radii of a few pc, reaching characteristic densities above $10^5$ M$_{\odot}$ pc$^{-2}$. The properties of the clusters in the lowest-mass galaxy bear a striking resemblance to those recently discovered by the James Webb Space Telescope (JWST) in the lensed Cosmic Gems arc system at $z = 10.2$. We argue that, due to their extremely high stellar densities, intermediate-mass black holes (IMBHs) would form rapidly inside the clusters, which would then swiftly sink and merge on their way to the galactic nucleus, easily growing a $10^7$~M$_{\odot}$ supermassive black hole (SMBH). Due to the high fractional mass contribution of clusters to the stellar mass of the galaxies, in the range $20$-$40\%$, the central SMBH would comprise more than $10\%$ of the mass of its host galaxy, naturally explaining the overmassive SMBHs discovered by JWST at $z > 6$.