Witnessing the violent, merger-driven formation of an extremely massive galaxy 1.7 Gyr after the Big Bang

Fuente: arXiv
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Autori principali: Pitchford, Lura K., Cairns, Joseph, Farrah, Duncan, Clements, David, Hatziminaoglou, Evanthia, Pérez-Fournon, Ismael, Wang, Lingyu
Natura: Preprint
Pubblicazione: 2025
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author Pitchford, Lura K.
Cairns, Joseph
Farrah, Duncan
Clements, David
Hatziminaoglou, Evanthia
Pérez-Fournon, Ismael
Wang, Lingyu
author_facet Pitchford, Lura K.
Cairns, Joseph
Farrah, Duncan
Clements, David
Hatziminaoglou, Evanthia
Pérez-Fournon, Ismael
Wang, Lingyu
contents We combine near-infrared imaging in two bands from the Hubble Space Telescope (HST) with archival observations of molecular gas to study SDSS J160705.16+533558.6 (J1607), an extremely luminous broad-line quasar at $z = 3.65$ that is also bright in the submillimeter (sub-mm). Via subtraction of the quasar point spread function, we show that its host galaxy is massive, with a stellar mass of $(5.8 \pm 3.0) \times 10^{11}$ M$_{\odot}$, making it comparable to giant early-type galaxies (ETGs) at $z\sim0$. If the supermassive black hole (SMBH) in the quasar is accreting at the Eddington limit, then its mass is $3.5 \times 10^{9}$ M$_{\odot}$, which is also consistent with local massive ETGs. The host has an extremely high star formation rate (SFR) of $4300 \pm 500$\sfr and a molecular gas mass of $(2.4 \pm 0.9)\times 10^{10}$ M$_{\odot}$. The quasar has two companions: one at a projected separation of 11 kpc with a stellar mass of $(7.9 \pm 5.0) \times 10^{10}$ M$_{\odot}$ but no detected molecular gas, and one 6 kpc further away in the same direction with a molecular gas mass of $(2.6 \pm 1.3) \times 10^{10}$ M$_{\odot}$ but no detected stellar emission. Since neither companion shows evidence for AGN activity, this may represent merger-driven quenching, in which the dynamics of the merger strip molecular gas from infalling galaxies. Overall, irrespective of whether the host is merging with the companions, these properties mark J1607 as forming what will become an extremely massive ($\sim10^{12}M_{\odot}$) galaxy by $z=0$.
format Preprint
id arxiv_https___arxiv_org_abs_2509_04584
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Witnessing the violent, merger-driven formation of an extremely massive galaxy 1.7 Gyr after the Big Bang
Pitchford, Lura K.
Cairns, Joseph
Farrah, Duncan
Clements, David
Hatziminaoglou, Evanthia
Pérez-Fournon, Ismael
Wang, Lingyu
Astrophysics of Galaxies
We combine near-infrared imaging in two bands from the Hubble Space Telescope (HST) with archival observations of molecular gas to study SDSS J160705.16+533558.6 (J1607), an extremely luminous broad-line quasar at $z = 3.65$ that is also bright in the submillimeter (sub-mm). Via subtraction of the quasar point spread function, we show that its host galaxy is massive, with a stellar mass of $(5.8 \pm 3.0) \times 10^{11}$ M$_{\odot}$, making it comparable to giant early-type galaxies (ETGs) at $z\sim0$. If the supermassive black hole (SMBH) in the quasar is accreting at the Eddington limit, then its mass is $3.5 \times 10^{9}$ M$_{\odot}$, which is also consistent with local massive ETGs. The host has an extremely high star formation rate (SFR) of $4300 \pm 500$\sfr and a molecular gas mass of $(2.4 \pm 0.9)\times 10^{10}$ M$_{\odot}$. The quasar has two companions: one at a projected separation of 11 kpc with a stellar mass of $(7.9 \pm 5.0) \times 10^{10}$ M$_{\odot}$ but no detected molecular gas, and one 6 kpc further away in the same direction with a molecular gas mass of $(2.6 \pm 1.3) \times 10^{10}$ M$_{\odot}$ but no detected stellar emission. Since neither companion shows evidence for AGN activity, this may represent merger-driven quenching, in which the dynamics of the merger strip molecular gas from infalling galaxies. Overall, irrespective of whether the host is merging with the companions, these properties mark J1607 as forming what will become an extremely massive ($\sim10^{12}M_{\odot}$) galaxy by $z=0$.
title Witnessing the violent, merger-driven formation of an extremely massive galaxy 1.7 Gyr after the Big Bang
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2509.04584