X-RAY OBSERVATIONS OF CYGNUS A USING THE GINGA SATELLITE

被引:68
作者
UENO, S
KOYAMA, K
NISHIDA, M
YAMAUCHI, S
WARD, MJ
机构
[1] IWATE UNIV,COLL HUMANITIES & SOCIAL SCI,MORIOKA,IWATE 020,JAPAN
[2] UNIV OXFORD,DEPT PHYS,OXFORD OX1 3RH,ENGLAND
关键词
GALAXIES; ACTIVE; INDIVIDUAL (CYGNUS A); NUCLEI; X-RAYS;
D O I
10.1086/187458
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
X-ray observations of Cypus A with the Ginga satellite require at least two components: (1) a power law with low energy absorption and (2) a thermal bremsstrahlung component with K-shell transition lines from highly ionized iron. The power law probably originates from the active galactic nucleus of Cypus A, as seen through a high column of gas. The photon index and hydrogen-equivalent column density are 1.98(+0.18/-0.20) and 3.75(+0.75/-0.71) X 10(23) H atoms cm-2, respectively. The luminosity corrected for this absorption column is about 10(45) ergs s-1 in the 2-10 keV band, which is within the range typical of ''quasars.'' This evidence strongly supports the idea that an obscured quasar resides at the center of Cygnus A. The thermal component can be attributed to emission from the hot intracluster gas. We have determined the X-ray luminosity and electron temperature of the intracluster gas to be 10(45) ergs s-1 and 7.3 keV, respectively. These X-ray properties are typical of those found for a rich cluster, although the environment suggests a poor cluster.
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页码:L1 / L4
页数:4
相关论文
共 36 条
[1]   3C 109 - AN OBSCURED X-RAY LUMINOUS QUASAR [J].
ALLEN, SW ;
FABIAN, AC .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1992, 258 (01) :P29-P32
[2]   UNIFIED MODELS FOR ACTIVE GALACTIC NUCLEI AND QUASARS [J].
ANTONUCCI, R .
ANNUAL REVIEW OF ASTRONOMY AND ASTROPHYSICS, 1993, 31 :473-521
[3]  
ANTONUCCI RA, 1994, UNPUB NATURE
[4]   SPECTROPOLARIMETRY AND THE NATURE OF NGC-1068 [J].
ANTONUCCI, RRJ ;
MILLER, JS .
ASTROPHYSICAL JOURNAL, 1985, 297 (02) :621-632
[5]   THE INTRACLUSTER GAS AROUND CYGNUS-A [J].
ARNAUD, KA ;
FABIAN, AC ;
EALES, SA ;
JONES, C ;
FORMAN, W .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1984, 211 (04) :981-989
[6]   X-RAY OBSERVATIONS OF THE OPHIUCHUS, PKS 0745-191 AND CYGNUS-A CLUSTERS OF GALAXIES [J].
ARNAUD, KA ;
JOHNSTONE, RM ;
FABIAN, AC ;
CRAWFORD, CS ;
NULSEN, PEJ ;
SHAFER, RA ;
MUSHOTZKY, RF .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1987, 227 (01) :241-&
[7]   GINGA OBSERVATIONS OF 3 X-RAY-LUMINOUS EARLY-TYPE GALAXIES - NGC-4472, NGC-4636, AND NGC-3998 [J].
AWAKI, H ;
KOYAMA, K ;
KUNIEDA, H ;
TAKANO, S ;
TAWARA, Y ;
OHASHI, T .
ASTROPHYSICAL JOURNAL, 1991, 366 (01) :88-94
[8]   X-RAY EVIDENCE OF AN OBSCURED NUCLEUS IN THE TYPE-2 SEYFERT-GALAXY MKN3 [J].
AWAKI, H ;
KOYAMA, K ;
KUNIEDA, H ;
TAWARA, Y .
NATURE, 1990, 346 (6284) :544-545
[9]  
AWAKI H, 1991, THESIS NAGOYA U
[10]   DISCOVERY OF AN INFRARED NUCLEUS IN CYGNUS-A - AN OBSCURED QUASAR REVEALED [J].
DJORGOVSKI, S ;
WEIR, N ;
MATTHEWS, K ;
GRAHAM, JR .
ASTROPHYSICAL JOURNAL, 1991, 372 (02) :L67-L70