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Titolo:
AN X-RAY SURVEY OF QUASARS USING ASCA
Autore:
REEVES JN; TURNER MJL; OHASHI T; KII T;
Indirizzi:
UNIV LEICESTER,DEPT PHYS & ASTRON,UNIV RD LEICESTER LE1 7RH LEICS ENGLAND TOKYO METROPOLITAN UNIV,DEPT PHYS HACHIOJI TOKYO 1920 JAPAN INST SPACE & ASTRONAUT SCI SAGAMIHARA KANAGAWA 229 JAPAN
Titolo Testata:
Monthly Notices of the Royal Astronomical Society
fascicolo: 2, volume: 292, anno: 1997,
pagine: 468 - 480
SICI:
0035-8711(1997)292:2<468:AXSOQU>2.0.ZU;2-U
Fonte:
ISI
Lingua:
ENG
Soggetto:
HIGH-REDSHIFT QUASARS; ACTIVE GALACTIC NUCLEI; PG 1211+143; ACCRETION DISKS; RADIO-SOURCES; SPECTRA; ABSORPTION; EMISSION; EVOLUTION; CONTINUUM;
Keywords:
SURVEYS; GALAXIES, ACTIVE; GALAXIES, NUCLEI; QUASARS, GENERAL; RADIO CONTINUUM, GALAXIES; X-RAYS, GALAXIES;
Tipo documento:
Article
Natura:
Periodico
Citazioni:
54
Recensione:
Indirizzi per estratti:
Citazione:
J.N. Reeves et al., "AN X-RAY SURVEY OF QUASARS USING ASCA", Monthly Notices of the Royal Astronomical Society, 292(2), 1997, pp. 468-480

Abstract

The ASCA X-ray observations of 24 quasars, with redshifts z > 0.05, are presented. The greater sensitivity and spectral resolution of ASCA extend the EXOSAT and Ginga surveys to higher redshifts. Significant intrinsic absorption is observed in some of the high-redshift objects, and a strong correlation is seen between absorption and quasar redshift, significant at > 99 per cent confidence level. The radio-loud objects in this survey are found, in general, to have flatter X-ray power-law spectra with weak or no iron fluorescence lines. In contrast, the radio-quiet quasars seem to have steeper spectra, with stronger iron lines, The mean photon index of the radio-quiet quasars is found to be 1.93 +/- 0.06, whereas the radio-loud quasars have a mean index of 1.63+/- 0.04. This corresponds to a significant difference in spectral shape between the radio-loud and radio-quiet quasars, at about the 99 per cent significance level, which was not found in the earlier Ginga sample.

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Documento generato il 18/09/20 alle ore 11:10:08