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Titolo:
Evidence of thick obscuring matter revealed in the X-ray spectrum of the z=4.28 quasar RX J1028.6-0844
Autore:
Yuan, W; Matsuoka, M; Wang, T; Ueno, S; Kubo, H; Mihara, T;
Indirizzi:
Natl Space Dev Agcy Japan, Tsukuba Space Ctr, Space Astrophys Grp, Tsukuba, Ibaraki 305, Japan Natl Space Dev Agcy Japan Tsukuba Ibaraki Japan 305 a, Ibaraki 305, Japan Univ Sci & Technol China, Ctr Astrophys, Anhua 230026, Peoples R China Univ Sci & Technol China Anhua Peoples R China 230026 6, Peoples R China Tokyo Inst Technol, Dept Phys, Meguro Ku, Tokyo 1528551, Japan Tokyo Inst Technol Tokyo Japan 1528551 , Meguro Ku, Tokyo 1528551, Japan RIKEN, Inst Phys & Chem Res, Wako, Saitama 3510198, Japan RIKEN Wako Saitama Japan 3510198 & Chem Res, Wako, Saitama 3510198, Japan
Titolo Testata:
ASTROPHYSICAL JOURNAL
fascicolo: 2, volume: 545, anno: 2000,
parte:, 1
pagine: 625 - 634
SICI:
0004-637X(200012)545:2<625:EOTOMR>2.0.ZU;2-7
Fonte:
ISI
Lingua:
ENG
Soggetto:
HIGH-REDSHIFT QUASARS; RADIO GALAXIES; COOLING FLOWS; H-I; ABSORPTION; ASCA; EVOLUTION; SYSTEMS; DISCOVERY; QSO;
Keywords:
quasars : absorption lines; quasars : individual (RX J1028.6-0844); X-rays : galaxies; X-rays : ISM;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
49
Recensione:
Indirizzi per estratti:
Indirizzo: Yuan, W Natl Space Dev Agcy Japan, Tsukuba Space Ctr, Space Astrophys Grp,2-1-1 Sengen, Tsukuba, Ibaraki 305, Japan Natl Space Dev Agcy Japan 2-1-1 Sengen Tsukuba Ibaraki Japan 305 n
Citazione:
W. Yuan et al., "Evidence of thick obscuring matter revealed in the X-ray spectrum of the z=4.28 quasar RX J1028.6-0844", ASTROPHYS J, 545(2), 2000, pp. 625-634

Abstract

We report the discovery of an unambiguous, substantial low-energy cutoff in the broadband X-ray spectrum of the radio quasar RX J1028.6-0844 at a redshift of 4.276 obtained with the ASCA satellite, which we preferably explained as an indication of excess X-ray absorption. The equivalent hydrogen column density of the absorbing matter, depending on the redshift and metallicity, ranges from 2.5 x 10(21) cm(-2) for local absorption up to 2.1 x 10(23) cm(-2) (solar metallicity) or 1.6 x 10(24) cm(-2) (10% solar metallicity) for absorption at the quasar redshift. Such a value is among the largest found for high-redshift radio quasars. The absorption, if interpreted as being produced close to the quasar, may indicate the presence of a remarkablylarge amount of obscuring matter in the quasar environment in the early universe. Implications of the result for the possible origins of the absorbing matter are discussed, concerning especially galactic intervening matter, cool intracluster gas, and ambient medium around the quasar jet. The quasaritself has an enormous apparent luminosity of at least about 2.6 x 10(47) ergs(-1) (H-0 = 50 km s(-1) Mpc(-1), q(0) = 0.5) and a power-law photon index of 1.67(-0.04)(+0.07) in the 2-50 keV band in the source rest frame.

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Documento generato il 31/03/20 alle ore 22:27:22