Cosmological evolution of supermassive black holes in galactic centers unveiled by hard X-ray observations
We review the current understanding of the cosmological evolution of supermassive black holes in galactic centers elucidated by X-ray surveys of active galactic nuclei (AGNs). Hard X-ray observations at energies above 2 keV are the most efficient and complete tools to find “obscured” AGNs, which are...
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| Format: | Online |
| Language: | English |
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The Japan Academy
2015
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| Online Access: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4561239/ |
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pubmed-45612392015-09-10 Cosmological evolution of supermassive black holes in galactic centers unveiled by hard X-ray observations UEDA, Yoshihiro Review We review the current understanding of the cosmological evolution of supermassive black holes in galactic centers elucidated by X-ray surveys of active galactic nuclei (AGNs). Hard X-ray observations at energies above 2 keV are the most efficient and complete tools to find “obscured” AGNs, which are dominant populations among all AGNs. Combinations of surveys with various flux limits and survey area have enabled us to determine the space number density and obscuration properties of AGNs as a function of luminosity and redshift. The results have essentially solved the origin of the X-ray background in the energy band below ∼10 keV. The downsizing (or anti-hierarchical) evolution that more luminous AGNs have the space-density peak at higher redshifts has been discovered, challenging theories of galaxy and black hole formation. Finally, we summarize unresolved issues on AGN evolution and prospects for future X-ray missions. The Japan Academy 2015-05-09 /pmc/articles/PMC4561239/ /pubmed/25971656 http://dx.doi.org/10.2183/pjab.91.175 Text en © 2015 The Japan Academy This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. |
| repository_type |
Open Access Journal |
| institution_category |
Foreign Institution |
| institution |
US National Center for Biotechnology Information |
| building |
NCBI PubMed |
| collection |
Online Access |
| language |
English |
| format |
Online |
| author |
UEDA, Yoshihiro |
| spellingShingle |
UEDA, Yoshihiro Cosmological evolution of supermassive black holes in galactic centers unveiled by hard X-ray observations |
| author_facet |
UEDA, Yoshihiro |
| author_sort |
UEDA, Yoshihiro |
| title |
Cosmological evolution of supermassive black holes in galactic centers unveiled by hard X-ray observations |
| title_short |
Cosmological evolution of supermassive black holes in galactic centers unveiled by hard X-ray observations |
| title_full |
Cosmological evolution of supermassive black holes in galactic centers unveiled by hard X-ray observations |
| title_fullStr |
Cosmological evolution of supermassive black holes in galactic centers unveiled by hard X-ray observations |
| title_full_unstemmed |
Cosmological evolution of supermassive black holes in galactic centers unveiled by hard X-ray observations |
| title_sort |
cosmological evolution of supermassive black holes in galactic centers unveiled by hard x-ray observations |
| description |
We review the current understanding of the cosmological evolution of supermassive black holes in galactic centers elucidated by X-ray surveys of active galactic nuclei (AGNs). Hard X-ray observations at energies above 2 keV are the most efficient and complete tools to find “obscured” AGNs, which are dominant populations among all AGNs. Combinations of surveys with various flux limits and survey area have enabled us to determine the space number density and obscuration properties of AGNs as a function of luminosity and redshift. The results have essentially solved the origin of the X-ray background in the energy band below ∼10 keV. The downsizing (or anti-hierarchical) evolution that more luminous AGNs have the space-density peak at higher redshifts has been discovered, challenging theories of galaxy and black hole formation. Finally, we summarize unresolved issues on AGN evolution and prospects for future X-ray missions. |
| publisher |
The Japan Academy |
| publishDate |
2015 |
| url |
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4561239/ |
| _version_ |
1613473156903731200 |