期刊
ASTROPHYSICAL JOURNAL
卷 892, 期 1, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.3847/1538-4357/ab789c
关键词
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资金
- European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant [788679]
- PRIN MIUR 2017
- CONICYT Doctorado Nacional [21161487]
- CONICYT [PIA ACT172033, Basal-CATA AFB-170002]
- CASSACA
- STFC [ST/P004172/1, ST/R000964/1] Funding Source: UKRI
We present a new modeling of the X-ray luminosity function (XLF) of active galactic nuclei (AGNs) out to z similar to 3, dissecting the contributions of main-sequence (MS) and starburst (SB) galaxies. For each galaxy population, we convolved the observed galaxy stellar mass (M-*) function with a grid of M-*- independent Eddington ratio (lambda(EDD)) distributions, normalized via empirical black hole accretion rate (BHAR) to star formation rate (SFR) relations. Our simple approach yields an excellent agreement with the observed XLF since z similar to 3. We find that the redshift evolution of the observed XLF can only be reproduced through an intrinsic flattening of the lambda(EDD) distribution and with a positive shift of the break lambda*, consistent with an antihierarchical behavior. The AGN accretion history is predominantly made by massive (10(10) < M-* < 10(11) M-circle dot) MS galaxies, while SB-driven BH accretion, possibly associated with galaxy mergers, becomes dominant only in bright quasars, at log(L-X/erg s(-1)) > 44.36 + 1.28 x (1 + z). We infer that the probability of finding highly accreting (lambda(EDD) > 10%) AGNs significantly increases with redshift, from 0.4% (3.0%) at z = 0.5%-6.5% (15.3%) at z = 3 for MS (SB) galaxies, implying a longer AGN duty cycle in the early universe. Our results strongly favor a M-*-dependent ratio between BHAR and SFR, as BHAR/SFR proportional to M-*(0.73[+0.22,-0.29]), supporting a nonlinear BH buildup relative to the host. Finally, this framework opens potential questions on super-Eddington BH accretion and different lambda(EDD) prescriptions for understanding the cosmic BH mass assembly.
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