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Main Authors: Sun, Hanwen, Wang, Tao, Xu, Ke, Daddi, Emanuele, Gu, Qing, Kodama, Tadayuki, Zanella, Anita, Elbaz, David, Tanaka, Ichi, Gobat, Raphael, Guo, Qi, Han, Jiaxin, Lu, Shiying, Zhou, Luwenjia
Format: Preprint
Published: 2024
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Online Access:https://arxiv.org/abs/2403.05248
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author Sun, Hanwen
Wang, Tao
Xu, Ke
Daddi, Emanuele
Gu, Qing
Kodama, Tadayuki
Zanella, Anita
Elbaz, David
Tanaka, Ichi
Gobat, Raphael
Guo, Qi
Han, Jiaxin
Lu, Shiying
Zhou, Luwenjia
author_facet Sun, Hanwen
Wang, Tao
Xu, Ke
Daddi, Emanuele
Gu, Qing
Kodama, Tadayuki
Zanella, Anita
Elbaz, David
Tanaka, Ichi
Gobat, Raphael
Guo, Qi
Han, Jiaxin
Lu, Shiying
Zhou, Luwenjia
contents Clusters and their progenitors (protoclusters) at z = 2-4, the peak epoch of star formation, are ideal laboratories to study the formation process of both the clusters themselves and their member galaxies. However, a complete census of their member galaxies has been challenging due to observational difficulties. Here we present new JWST/NIRCam observations targeting the distant cluster CLJ1001 at z = 2.51 from the COSMOS-Web program, which, in combination with previous narrowband imaging targeting H-alpha emitters and deep millimeter surveys of CO emitters, provide a complete view of massive galaxy assembly in CLJ1001. In particular, JWST reveals a population of massive, extremely red cluster members in the long-wavelength bands that were invisible in previous Hubble Space Telescope (HST)/F160W imaging (HST-dark members). Based on this highly complete spectroscopic sample of member galaxies, we show that the spatial distribution of galaxies in CLJ1001 exhibits a strong central concentration, with the central galaxy density already resembling that of low-z clusters. Moreover, we reveal a "top-heavy" stellar mass function for the star-forming galaxies (SFGs), with an overabundance of massive SFGs piled up in the cluster core. These features strongly suggest that CLJ1001 is caught in a rapid transition, with many of its massive SFGs likely soon becoming quiescent. In the context of cluster formation, these findings suggest that the earliest clusters form from the inside out and top to bottom, with the massive galaxies in the core assembling first, followed by the less massive ones in the outskirts.
format Preprint
id arxiv_https___arxiv_org_abs_2403_05248
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle JWST's first glimpse of a z > 2 forming cluster reveals a top-heavy stellar mass function
Sun, Hanwen
Wang, Tao
Xu, Ke
Daddi, Emanuele
Gu, Qing
Kodama, Tadayuki
Zanella, Anita
Elbaz, David
Tanaka, Ichi
Gobat, Raphael
Guo, Qi
Han, Jiaxin
Lu, Shiying
Zhou, Luwenjia
Astrophysics of Galaxies
Clusters and their progenitors (protoclusters) at z = 2-4, the peak epoch of star formation, are ideal laboratories to study the formation process of both the clusters themselves and their member galaxies. However, a complete census of their member galaxies has been challenging due to observational difficulties. Here we present new JWST/NIRCam observations targeting the distant cluster CLJ1001 at z = 2.51 from the COSMOS-Web program, which, in combination with previous narrowband imaging targeting H-alpha emitters and deep millimeter surveys of CO emitters, provide a complete view of massive galaxy assembly in CLJ1001. In particular, JWST reveals a population of massive, extremely red cluster members in the long-wavelength bands that were invisible in previous Hubble Space Telescope (HST)/F160W imaging (HST-dark members). Based on this highly complete spectroscopic sample of member galaxies, we show that the spatial distribution of galaxies in CLJ1001 exhibits a strong central concentration, with the central galaxy density already resembling that of low-z clusters. Moreover, we reveal a "top-heavy" stellar mass function for the star-forming galaxies (SFGs), with an overabundance of massive SFGs piled up in the cluster core. These features strongly suggest that CLJ1001 is caught in a rapid transition, with many of its massive SFGs likely soon becoming quiescent. In the context of cluster formation, these findings suggest that the earliest clusters form from the inside out and top to bottom, with the massive galaxies in the core assembling first, followed by the less massive ones in the outskirts.
title JWST's first glimpse of a z > 2 forming cluster reveals a top-heavy stellar mass function
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2403.05248