_version_ 1866918178299314176
author Zhang, Yiyang
Ding, Xuheng
Yang, Lilan
Lambrides, Erini
Akins, Hollis
Battisti, Andrew J.
Casey, Caitlin M.
Chen, Chang-hao
Cox, Isa
Faisst, Andreas
Franco, Maximilien
Haghjoo, Aryana
Ho, Luis C.
Inayoshi, Kohei
Jin, Shuowen
Karmen, Mitchell
Koekemoer, Anton M.
Kartaltepe, Jeyhan S.
Liao, Kai
Gozaliasl, Ghassem
Onoue, Masafusa
Kokorev, Vasily
Roy, Namrata
Rich, R. Michael
Silverman, John D.
Tanaka, Takumi S.
You, Bei
Yesuf, Hassen M.
Zavala, Jorge A.
author_facet Zhang, Yiyang
Ding, Xuheng
Yang, Lilan
Lambrides, Erini
Akins, Hollis
Battisti, Andrew J.
Casey, Caitlin M.
Chen, Chang-hao
Cox, Isa
Faisst, Andreas
Franco, Maximilien
Haghjoo, Aryana
Ho, Luis C.
Inayoshi, Kohei
Jin, Shuowen
Karmen, Mitchell
Koekemoer, Anton M.
Kartaltepe, Jeyhan S.
Liao, Kai
Gozaliasl, Ghassem
Onoue, Masafusa
Kokorev, Vasily
Roy, Namrata
Rich, R. Michael
Silverman, John D.
Tanaka, Takumi S.
You, Bei
Yesuf, Hassen M.
Zavala, Jorge A.
contents Recent JWST observations have revealed a population of red, compact, high-redshift objects called 'Little Red Dots'(LRD), whose host components have remained largely unconstrained, possibly due to their extreme compactness. Current morphological studies have been limited by small samples, as well as by insufficient imaging depth, which may not allow reliable separation between point-like and extended components, leaving the existence and properties of extended components in LRD largely unconstrained. Here, we perform the image stacking analysis of 217 LRDs in four NIRCam bands, representing the largest and homogeneous sample observed from COSMOS-Web survey to date. Our results reveal an unambiguous detection of faint extended emission in the F444W band, with a typical size of ~200 parsecs and magnitude of ~27.7 AB at z~6.5. We perform four-band photometric SED fitting based on galaxy templates and derive a stellar mass of 8.91+-~0.1 logM_sun. Given this stellar mass, the host galaxy is compact, i.e., ~2.5 times smaller than star-forming populations at similar mass, and the typical black hole mass of LRDs is elevated by ~1.5 dex above the local MBH-M* relation. This work provides direct observational evidence for the existence of LRD host galaxies and offers crucial insights into the growth of the host galaxy and the co-evolution of galaxies and their black holes within the first billion years after the Big Bang.
format Preprint
id arxiv_https___arxiv_org_abs_2510_25830
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Unveiling Extended Components of 'Little Red Dots' in Rest-Frame Optical
Zhang, Yiyang
Ding, Xuheng
Yang, Lilan
Lambrides, Erini
Akins, Hollis
Battisti, Andrew J.
Casey, Caitlin M.
Chen, Chang-hao
Cox, Isa
Faisst, Andreas
Franco, Maximilien
Haghjoo, Aryana
Ho, Luis C.
Inayoshi, Kohei
Jin, Shuowen
Karmen, Mitchell
Koekemoer, Anton M.
Kartaltepe, Jeyhan S.
Liao, Kai
Gozaliasl, Ghassem
Onoue, Masafusa
Kokorev, Vasily
Roy, Namrata
Rich, R. Michael
Silverman, John D.
Tanaka, Takumi S.
You, Bei
Yesuf, Hassen M.
Zavala, Jorge A.
Astrophysics of Galaxies
Recent JWST observations have revealed a population of red, compact, high-redshift objects called 'Little Red Dots'(LRD), whose host components have remained largely unconstrained, possibly due to their extreme compactness. Current morphological studies have been limited by small samples, as well as by insufficient imaging depth, which may not allow reliable separation between point-like and extended components, leaving the existence and properties of extended components in LRD largely unconstrained. Here, we perform the image stacking analysis of 217 LRDs in four NIRCam bands, representing the largest and homogeneous sample observed from COSMOS-Web survey to date. Our results reveal an unambiguous detection of faint extended emission in the F444W band, with a typical size of ~200 parsecs and magnitude of ~27.7 AB at z~6.5. We perform four-band photometric SED fitting based on galaxy templates and derive a stellar mass of 8.91+-~0.1 logM_sun. Given this stellar mass, the host galaxy is compact, i.e., ~2.5 times smaller than star-forming populations at similar mass, and the typical black hole mass of LRDs is elevated by ~1.5 dex above the local MBH-M* relation. This work provides direct observational evidence for the existence of LRD host galaxies and offers crucial insights into the growth of the host galaxy and the co-evolution of galaxies and their black holes within the first billion years after the Big Bang.
title Unveiling Extended Components of 'Little Red Dots' in Rest-Frame Optical
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2510.25830