In Situ Star Formation in Accretion Disks and Explanation of Correlation between the Black Hole Mass and Metallicity in Active Galactic Nuclei
Abstract Recent observations show that the metallicity Z BLR of the broad-line region (BLR) in active galactic nuclei (AGNs) is solar to supersolar, which is positively correlated with the mass of supermassive black holes ( M BH ) and does not evolve with the redshift up to z ∼ 7. We revisit the M B...
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Published in | The Astrophysical journal Vol. 944; no. 2; pp. 159 - 169 |
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Main Authors | , |
Format | Journal Article |
Language | English |
Published |
Philadelphia
The American Astronomical Society
01.02.2023
IOP Publishing |
Subjects | |
Online Access | Get full text |
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Summary: | Abstract
Recent observations show that the metallicity
Z
BLR
of the broad-line region (BLR) in active galactic nuclei (AGNs) is solar to supersolar, which is positively correlated with the mass of supermassive black holes (
M
BH
) and does not evolve with the redshift up to
z
∼ 7. We revisit the
M
BH
−
Z
BLR
correlation with more AGNs with
M
BH
∼ 10
6–8
M
⊙
and find that the positive correlation becomes flat in the low-mass range. It is known that the outer part of accretion disks is gravitationally unstable and can fragment into stars. Considering the star formation and supernovae in the outer AGN disk, we calculate the metal enrichment and find that the positive
M
BH
−
Z
BLR
correlation can be roughly reproduced if the stellar mass distribution is “top heavy.” We find that the observed BLR size is more or less similar to the self-gravity radius of the AGN disk, which suggests that the BLR may be closely correlated with the underlying accretion process. |
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Bibliography: | High-Energy Phenomena and Fundamental Physics AAS42784 |
ISSN: | 0004-637X 1538-4357 |
DOI: | 10.3847/1538-4357/acb532 |