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Title: How long do high redshift massive black hole seeds remain outliers in black hole versus host galaxy relations?
ABSTRACT

The existence of 109 M⊙ supermassive black holes (SMBHs) within the first billion years of the Universe remains a puzzle in our conventional understanding of black hole formation and growth. Several suggested formation pathways for these SMBHs lead to a heavy seed, with an initial black hole mass of 104–106 M⊙. This can lead to an overly massive BH galaxy (OMBG), whose nuclear black hole’s mass is comparable to or even greater than the surrounding stellar mass: the black hole to stellar mass ratio is Mbh/M* ≫ 10−3, well in excess of the typical values at lower redshift. We investigate how long these newborn BHs remain outliers in the Mbh − M* relation, by exploring the subsequent evolution of two OMBGs previously identified in the Renaissance simulations. We find that both OMBGs have Mbh/M* > 1 during their entire life, from their birth at z ≈ 15 until they merge with much more massive haloes at z ≈ 8. We find that the OMBGs are spatially resolvable from their more massive, 1011 M⊙, neighbouring haloes until their mergers are complete at z ≈ 8. This affords a window for future observations with JWST and sensitive X-ray telescopes to diagnose the heavy-seed scenario, by detecting similar OMBGs and establishing their uniquely high black hole-to-stellar mass ratio.

 
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Award ID(s):
1835213
NSF-PAR ID:
10388571
Author(s) / Creator(s):
; ;
Publisher / Repository:
Oxford University Press
Date Published:
Journal Name:
Monthly Notices of the Royal Astronomical Society
Volume:
519
Issue:
2
ISSN:
0035-8711
Format(s):
Medium: X Size: p. 2155-2168
Size(s):
["p. 2155-2168"]
Sponsoring Org:
National Science Foundation
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