NAOC Open IR
The X-ray properties of z > 6 quasars: no evident evolution of accretion physics in the first Gyr of the Universe
Vito, F.1,2,3,4,5; Brandt, W. N.4,5,6; Bauer, F. E.1,2,7,8; Calura, F.9; Gilli, R.9; Luo, B.10,11; Shemmer, O.12; Vignali, C.9,13; Zamorani, G.9; Brusa, M.9,13; Civano, F.14; Comastri, A.9; Nanni, R.9,13
2019-10-02
Source PublicationASTRONOMY & ASTROPHYSICS
ISSN0004-6361
Volume630Pages:16
AbstractContext. X-ray emission from quasars (QSOs) has been used to assess supermassive black hole accretion properties up to z approximate to 6. However, at z > 6 only approximate to 15 QSOs are covered by sensitive X-ray observations, preventing a statistically significant investigation of the X-ray properties of the QSO population in the first Gyr of the Universe. Aims. We present new Chandra observations of a sample of 10 z > 6 QSOs, selected to have virial black-hole mass estimates from Mg II line spectroscopy (logM(BH)/M-circle dot = 8.5-9.6). Adding archival X-ray data for an additional 15 z > 6 QSOs, we investigate the X-ray properties of the QSO population in the first Gyr of the Universe. In particular, we focus on the L-UV-L-X relation, which is traced by the alpha(ox) parameter, and the shape of their X-ray spectra. Methods. We performed photometric analyses to derive estimates of the X-ray luminosities of our z > 6 QSOs, and thus their alpha(ox) values and bolometric corrections (K-bol = L-bol/L-X). We compared the resulting alpha(ox) and K-bol distributions with the results found for QSO samples at lower redshift, and ran several statistical tests to check for a possible evolution of the L-UV-L-X relation. Finally, we performed a basic X-ray spectral analysis of the brightest z > 6 QSOs to derive their individual photon indices, and joint spectral analysis of the whole sample to estimate the average photon index. Results. We detect seven of the new Chandra targets in at least one standard energy band, while two more are detected discarding energies E > 5 keV, where background dominates. We confirm a lack of significant evolution of alpha(ox) with redshift, which extends the results from previous works up to z > 6 with a statistically significant QSO sample. Furthermore, we confirm the trend of an increasing bolometric correction with increasing luminosity found for QSOs at lower redshifts. The average power-law photon index of our sample ( = 2.20(-0.34)(+0.39) and = 2.13(-0.13)(+0.13) for sources with < 30 and >30 net counts, respectively) is slightly steeper than, but still consistent with, typical QSOs at z = 1 - 6. Conclusions. All of these results indicate a lack of substantial evolution of the inner accretion-disk and hot-corona structure in QSOs from low redshift to z > 6. Our data hint at generally high Eddington ratios at z > 6.
Keywordmethods: data analysis galaxies: active galaxies: nuclei X-rays: galaxies galaxies: high-redshift quasars: general
Funding OrganizationCONICYT ; CONICYT ; CASSACA through the Fourth call for tenders of the CAS-CONICYT Fund ; CASSACA through the Fourth call for tenders of the CAS-CONICYT Fund ; Ministry of Economy, Development, and Tourism's Millennium Science Initiative ; Ministry of Economy, Development, and Tourism's Millennium Science Initiative ; CXC ; CXC ; NASA ADP grant ; NASA ADP grant ; National Key R&D Program of China ; National Key R&D Program of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; ASI-INAF ; ASI-INAF ; CONICYT ; CONICYT ; CASSACA through the Fourth call for tenders of the CAS-CONICYT Fund ; CASSACA through the Fourth call for tenders of the CAS-CONICYT Fund ; Ministry of Economy, Development, and Tourism's Millennium Science Initiative ; Ministry of Economy, Development, and Tourism's Millennium Science Initiative ; CXC ; CXC ; NASA ADP grant ; NASA ADP grant ; National Key R&D Program of China ; National Key R&D Program of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; ASI-INAF ; ASI-INAF ; CONICYT ; CONICYT ; CASSACA through the Fourth call for tenders of the CAS-CONICYT Fund ; CASSACA through the Fourth call for tenders of the CAS-CONICYT Fund ; Ministry of Economy, Development, and Tourism's Millennium Science Initiative ; Ministry of Economy, Development, and Tourism's Millennium Science Initiative ; CXC ; CXC ; NASA ADP grant ; NASA ADP grant ; National Key R&D Program of China ; National Key R&D Program of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; ASI-INAF ; ASI-INAF ; CONICYT ; CONICYT ; CASSACA through the Fourth call for tenders of the CAS-CONICYT Fund ; CASSACA through the Fourth call for tenders of the CAS-CONICYT Fund ; Ministry of Economy, Development, and Tourism's Millennium Science Initiative ; Ministry of Economy, Development, and Tourism's Millennium Science Initiative ; CXC ; CXC ; NASA ADP grant ; NASA ADP grant ; National Key R&D Program of China ; National Key R&D Program of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; ASI-INAF ; ASI-INAF
DOI10.1051/0004-6361/201936217
WOS KeywordDIGITAL SKY SURVEY ; ACTIVE GALACTIC NUCLEI ; HIGHEST REDSHIFT QUASARS ; BLACK-HOLE GROWTH ; DATA RELEASE ; Z-GREATER-THAN-5.7 QUASARS ; CHANDRA OBSERVATIONS ; LUMINOUS QUASARS ; EDDINGTON-RATIO ; SPECTRAL SLOPE
Language英语
Funding ProjectCONICYT[Basal-CATA AFB-170002] ; CASSACA through the Fourth call for tenders of the CAS-CONICYT Fund[Basal-CATA AFB-170002] ; Ministry of Economy, Development, and Tourism's Millennium Science Initiative[IC120009] ; CXC[G08-19076X] ; NASA ADP grant[80NSSC18K0878] ; National Key R&D Program of China[2016YFA0400702] ; National Natural Science Foundation of China[11673010] ; ASI-INAF[2017-14-H.O]
Funding OrganizationCONICYT ; CONICYT ; CASSACA through the Fourth call for tenders of the CAS-CONICYT Fund ; CASSACA through the Fourth call for tenders of the CAS-CONICYT Fund ; Ministry of Economy, Development, and Tourism's Millennium Science Initiative ; Ministry of Economy, Development, and Tourism's Millennium Science Initiative ; CXC ; CXC ; NASA ADP grant ; NASA ADP grant ; National Key R&D Program of China ; National Key R&D Program of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; ASI-INAF ; ASI-INAF ; CONICYT ; CONICYT ; CASSACA through the Fourth call for tenders of the CAS-CONICYT Fund ; CASSACA through the Fourth call for tenders of the CAS-CONICYT Fund ; Ministry of Economy, Development, and Tourism's Millennium Science Initiative ; Ministry of Economy, Development, and Tourism's Millennium Science Initiative ; CXC ; CXC ; NASA ADP grant ; NASA ADP grant ; National Key R&D Program of China ; National Key R&D Program of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; ASI-INAF ; ASI-INAF ; CONICYT ; CONICYT ; CASSACA through the Fourth call for tenders of the CAS-CONICYT Fund ; CASSACA through the Fourth call for tenders of the CAS-CONICYT Fund ; Ministry of Economy, Development, and Tourism's Millennium Science Initiative ; Ministry of Economy, Development, and Tourism's Millennium Science Initiative ; CXC ; CXC ; NASA ADP grant ; NASA ADP grant ; National Key R&D Program of China ; National Key R&D Program of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; ASI-INAF ; ASI-INAF ; CONICYT ; CONICYT ; CASSACA through the Fourth call for tenders of the CAS-CONICYT Fund ; CASSACA through the Fourth call for tenders of the CAS-CONICYT Fund ; Ministry of Economy, Development, and Tourism's Millennium Science Initiative ; Ministry of Economy, Development, and Tourism's Millennium Science Initiative ; CXC ; CXC ; NASA ADP grant ; NASA ADP grant ; National Key R&D Program of China ; National Key R&D Program of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; ASI-INAF ; ASI-INAF
WOS Research AreaAstronomy & Astrophysics
WOS SubjectAstronomy & Astrophysics
WOS IDWOS:000516616500001
PublisherEDP SCIENCES S A
Citation statistics
Document Type期刊论文
Identifierhttp://ir.bao.ac.cn/handle/114a11/54456
Collection中国科学院国家天文台
Corresponding AuthorVito, F.
Affiliation1.Pontificia Univ Catolica Chile, Fac Fis, Inst Astrofis, Casilla 306, Santiago 22, Chile
2.Pontificia Univ Catolica Chile, Fac Fis, Ctr Astroingn, Casilla 306, Santiago 22, Chile
3.Chinese Acad Sci, South Amer Ctr Astron, Natl Astron Observ, Beijing 100012, Peoples R China
4.Penn State Univ, Dept Astron & Astrophys, 525 Davey Lab, University Pk, PA 16802 USA
5.Penn State Univ, Inst Gravitat & Cosmos, University Pk, PA 16802 USA
6.Penn State Univ, Dept Phys, 104 Davey Lab, University Pk, PA 16802 USA
7.Millennium Inst Astrophys MAS, Nuncio Monsenor Sotero Sanz 100, Santiago, Chile
8.Space Sci Inst, 4750 Walnut St,Suite 205, Boulder, CO 80301 USA
9.INAF Osservatorio Astrofis & Sci Spazio Bologna, Via Gobetti 93-3, I-40129 Bologna, Italy
10.Nanjing Univ, Sch Astron & Space Sci, Nanjing 210093, Peoples R China
11.Nanjing Univ, Minist Educ, Key Lab Modern Astron & Astrophys, Nanjing 210093, Jiangsu, Peoples R China
12.Univ North Texas, Dept Phys, Denton, TX 76203 USA
13.Univ Bologna, Dipartimento Fis & Astron, Via Gobetti 93-2, I-40129 Bologna, Italy
14.15 Ctr Astrophys Harvard & Smithsonian, 60 Garden St, Cambridge, MA 02138 USA
Recommended Citation
GB/T 7714
Vito, F.,Brandt, W. N.,Bauer, F. E.,et al. The X-ray properties of z > 6 quasars: no evident evolution of accretion physics in the first Gyr of the Universe[J]. ASTRONOMY & ASTROPHYSICS,2019,630:16.
APA Vito, F..,Brandt, W. N..,Bauer, F. E..,Calura, F..,Gilli, R..,...&Nanni, R..(2019).The X-ray properties of z > 6 quasars: no evident evolution of accretion physics in the first Gyr of the Universe.ASTRONOMY & ASTROPHYSICS,630,16.
MLA Vito, F.,et al."The X-ray properties of z > 6 quasars: no evident evolution of accretion physics in the first Gyr of the Universe".ASTRONOMY & ASTROPHYSICS 630(2019):16.
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