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Title: The Formation of Supermassive Black Holes from Population III.1 Seeds. I. Cosmic Formation Histories and Clustering Properties

Abstract

We calculate the cosmic distributions in space and time of the formation sites of the first, "Pop III.1" stars, exploring a model in which these are the progenitors of all supermassive black holes (SMBHs). Pop III.1 stars are defined to form from primordial composition gas in dark matter minihalos with $$\sim10^6\:M_\odot$$ that are isolated from neighboring astrophysical sources by a given isolation distance, $$d_{\rm{iso}}$$. We assume Pop III.1 sources are seeds of SMBHs, based on protostellar support by dark matter annihilation heating that allows them to accrete a large fraction of their minihalo gas, i.e., $$\sim 10^5\:M_\odot$$. Exploring $$d_{\rm{iso}}$$ from 10--$$100\:\rm{kpc}$$ (proper distances), we predict the redshift evolution of Pop III.1 source and SMBH remnant number densities. The local, $z=0$ density of SMBHs constrains $$d_{\rm{iso}}\lesssim 100\:\rm{kpc}$$ (i.e., $$3\:\rm{Mpc}$$ comoving distance at $$z\simeq30$$). In our simulated ($$\sim60\:\rm{Mpc}$$)$^3$ comoving volume, Pop III.1 stars start forming just after $z=40$. Their formation is largely complete by $$z\simeq25$$ to 20 for $$d_{\rm{iso}}=100$$ to $$50\:\rm{kpc}$$. We follow source evolution to $z=10$, by which point most SMBHs reside in halos with $$\gtrsim10^8\:M_\odot$$. Over this period, there is relatively limited merging of SMBHs for these values of $$d_{\rm{iso}}$$. We also predict SMBH clustering properties at $z=10$$: feedback suppression of neighboring sources leads to relatively flat angular correlation functions. Finally, we consider a simple "Str\"omgren" model for $$d_{\rm iso}$, based on ionizing feedback from zero age main sequence supermassive Pop III.1 stars that may be the direct progenitors of SMBHs in this scenario. Such models naturally produce feedback effects on scales of $$\sim100\:$$kpc and thus self-consistently generate a SMBH number density similar to the observed value.

Authors:
; ;
Publication Date:
Research Org.:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
OSTI Identifier:
1374712
Report Number(s):
FERMILAB-PUB-16-322-A-AE-PPD-T; arXiv:1608.04421
1481372
DOE Contract Number:
AC02-07CH11359
Resource Type:
Journal Article
Resource Relation:
Journal Name: TBD
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS

Citation Formats

Banik, Nilanjan, Tan, Jonathan C., and Monaco, Pierluigi. The Formation of Supermassive Black Holes from Population III.1 Seeds. I. Cosmic Formation Histories and Clustering Properties. United States: N. p., 2016. Web.
Banik, Nilanjan, Tan, Jonathan C., & Monaco, Pierluigi. The Formation of Supermassive Black Holes from Population III.1 Seeds. I. Cosmic Formation Histories and Clustering Properties. United States.
Banik, Nilanjan, Tan, Jonathan C., and Monaco, Pierluigi. 2016. "The Formation of Supermassive Black Holes from Population III.1 Seeds. I. Cosmic Formation Histories and Clustering Properties". United States. doi:. https://www.osti.gov/servlets/purl/1374712.
@article{osti_1374712,
title = {The Formation of Supermassive Black Holes from Population III.1 Seeds. I. Cosmic Formation Histories and Clustering Properties},
author = {Banik, Nilanjan and Tan, Jonathan C. and Monaco, Pierluigi},
abstractNote = {We calculate the cosmic distributions in space and time of the formation sites of the first, "Pop III.1" stars, exploring a model in which these are the progenitors of all supermassive black holes (SMBHs). Pop III.1 stars are defined to form from primordial composition gas in dark matter minihalos with $\sim10^6\:M_\odot$ that are isolated from neighboring astrophysical sources by a given isolation distance, $d_{\rm{iso}}$. We assume Pop III.1 sources are seeds of SMBHs, based on protostellar support by dark matter annihilation heating that allows them to accrete a large fraction of their minihalo gas, i.e., $\sim 10^5\:M_\odot$. Exploring $d_{\rm{iso}}$ from 10--$100\:\rm{kpc}$ (proper distances), we predict the redshift evolution of Pop III.1 source and SMBH remnant number densities. The local, $z=0$ density of SMBHs constrains $d_{\rm{iso}}\lesssim 100\:\rm{kpc}$ (i.e., $3\:\rm{Mpc}$ comoving distance at $z\simeq30$). In our simulated ($\sim60\:\rm{Mpc}$)$^3$ comoving volume, Pop III.1 stars start forming just after $z=40$. Their formation is largely complete by $z\simeq25$ to 20 for $d_{\rm{iso}}=100$ to $50\:\rm{kpc}$. We follow source evolution to $z=10$, by which point most SMBHs reside in halos with $\gtrsim10^8\:M_\odot$. Over this period, there is relatively limited merging of SMBHs for these values of $d_{\rm{iso}}$. We also predict SMBH clustering properties at $z=10$: feedback suppression of neighboring sources leads to relatively flat angular correlation functions. Finally, we consider a simple "Str\"omgren" model for $d_{\rm iso}$, based on ionizing feedback from zero age main sequence supermassive Pop III.1 stars that may be the direct progenitors of SMBHs in this scenario. Such models naturally produce feedback effects on scales of $\sim100\:$kpc and thus self-consistently generate a SMBH number density similar to the observed value.},
doi = {},
journal = {TBD},
number = ,
volume = ,
place = {United States},
year = 2016,
month = 8
}
  • The existence of 10{sup 9} M{sub Sun} black holes (BHs) in massive galaxies by z {approx} 7 is one of the great unsolved mysteries in cosmological structure formation. One theory argues that they originate from the BHs of Pop III stars at z {approx} 20 and then accrete at the Eddington limit down to the epoch of reionization, which requires that they have constant access to rich supplies of fuel. Because early numerical simulations suggested that Pop III stars were {approx}>100 M{sub Sun }, the supermassive black hole (SMBH) seeds considered up to now were 100-300 M{sub Sun }. However,more » there is a growing numerical and observational consensus that some Pop III stars were tens of solar masses, not hundreds, and that 20-40 M{sub Sun} BHs may have been much more plentiful at high redshift. However, we find that natal kicks imparted to 20-40 M{sub Sun} Pop III BHs during formation eject them from their halos and hence their fuel supply, precluding them from Eddington-limit growth. Consequently, SMBHs are far less likely to form from low-mass Pop III stars than from very massive ones.« less
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  • Recent observations of quasars powered by supermassive black holes (SMBHs) out to z {approx}> 7 constrain both the initial seed masses and the growth of the most massive black holes (BHs) in the early universe. Here we elucidate the implications of the radiative feedback from early generations of stars and from BH accretion for popular models for the formation and growth of seed BHs. We show that by properly accounting for (1) the limited role of mergers in growing seed BHs as inferred from cosmological simulations of early star formation and radiative feedback, (2) the sub-Eddington accretion rates of BHsmore » expected at the earliest times, and (3) the large radiative efficiencies {epsilon} of the most massive BHs inferred from observations of active galactic nuclei at high redshift ({epsilon} {approx}> 0.1), we are led to the conclusion that the initial BH seeds may have been as massive as {approx}> 10{sup 5} M{sub Sun }. This presents a strong challenge to the Population III seed model, which calls for seed masses of {approx}100 M{sub Sun} and, even with constant Eddington-limited accretion, requires {epsilon} {approx}< 0.09 to explain the highest-z SMBHs in today's standard {Lambda}CDM cosmological model. It is, however, consistent with the prediction of the direct collapse scenario of SMBH seed formation, in which a supermassive primordial star forms in a region of the universe with a high molecule-dissociating background radiation field, and collapses directly into a 10{sup 4}-10{sup 6} M{sub Sun} seed BH. These results corroborate recent cosmological simulations and observational campaigns which suggest that these massive BHs were the seeds of a large fraction of the SMBHs residing in the centers of galaxies today.« less
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