Overmassive Black holes live in compact galaxies in the early Universe

Fuente: arXiv
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Main Authors: Wu, Yuxuan, Wang, Tao, Liu, Daizhong, Tan, Qinghua, Ho, Luis C., Zhang, Zhiyu, Shi, Yong, Xu, Ke, Kohno, Kotaro, Wang, Ran, Izumi, Takuma, Li, Zhaozhou
Format: Preprint
Published: 2025
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author Wu, Yuxuan
Wang, Tao
Liu, Daizhong
Tan, Qinghua
Ho, Luis C.
Zhang, Zhiyu
Shi, Yong
Xu, Ke
Kohno, Kotaro
Wang, Ran
Izumi, Takuma
Li, Zhaozhou
author_facet Wu, Yuxuan
Wang, Tao
Liu, Daizhong
Tan, Qinghua
Ho, Luis C.
Zhang, Zhiyu
Shi, Yong
Xu, Ke
Kohno, Kotaro
Wang, Ran
Izumi, Takuma
Li, Zhaozhou
contents A significant population of quasars have been found to exist within the first Gyr of cosmic time. Most of them have high black hole (BH) masses ($M_{\rm BH} \sim 10^{8-10} M_{\odot}$) with an elevated BH-to-stellar mass ratio compared to typical local galaxies, posing challenges to our understanding of the formation of supermassive BHs and their coevolution with host galaxies. Here, based on size measurements of [CII] 158$μ$m emission for a statistical sample of $z \sim 6$ quasars, we find that their host galaxies are systematically more compact (with half-light radius $R_{\rm e} \sim 1.6$ kpc) than typical star-forming galaxies at the same redshifts. Specifically, the sizes of the most compact quasar hosts, which also tend to contain less cold gas than their more extended counterparts, are comparable to that of massive quiescent galaxies at $z \sim 4-5$. These findings reveal an intimate connection between the formation of massive BHs and compactness of their host galaxies in the early universe. These compact quasar hosts are promising progenitors of the first population of quiescent galaxies.
format Preprint
id arxiv_https___arxiv_org_abs_2506_14896
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Overmassive Black holes live in compact galaxies in the early Universe
Wu, Yuxuan
Wang, Tao
Liu, Daizhong
Tan, Qinghua
Ho, Luis C.
Zhang, Zhiyu
Shi, Yong
Xu, Ke
Kohno, Kotaro
Wang, Ran
Izumi, Takuma
Li, Zhaozhou
Astrophysics of Galaxies
Cosmology and Nongalactic Astrophysics
A significant population of quasars have been found to exist within the first Gyr of cosmic time. Most of them have high black hole (BH) masses ($M_{\rm BH} \sim 10^{8-10} M_{\odot}$) with an elevated BH-to-stellar mass ratio compared to typical local galaxies, posing challenges to our understanding of the formation of supermassive BHs and their coevolution with host galaxies. Here, based on size measurements of [CII] 158$μ$m emission for a statistical sample of $z \sim 6$ quasars, we find that their host galaxies are systematically more compact (with half-light radius $R_{\rm e} \sim 1.6$ kpc) than typical star-forming galaxies at the same redshifts. Specifically, the sizes of the most compact quasar hosts, which also tend to contain less cold gas than their more extended counterparts, are comparable to that of massive quiescent galaxies at $z \sim 4-5$. These findings reveal an intimate connection between the formation of massive BHs and compactness of their host galaxies in the early universe. These compact quasar hosts are promising progenitors of the first population of quiescent galaxies.
title Overmassive Black holes live in compact galaxies in the early Universe
topic Astrophysics of Galaxies
Cosmology and Nongalactic Astrophysics
url https://arxiv.org/abs/2506.14896