THE PROXIMITY EFFECT AND THE MEAN INTENSITY OF IONIZING-RADIATION AT LOW REDSHIFTS

被引:78
作者
KULKARNI, VP [1 ]
FALL, SM [1 ]
机构
[1] UNIV CHICAGO,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637
关键词
DIFFUSE RADIATION; INTERGALACTIC MEDIUM; QUASARS; ABSORPTION LINES;
D O I
10.1086/186960
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We report the first tentative detection of the proximity effect in the distribution of Lyalpha forest lines at low redshifts (z less than or similar to 1). This is based on observations of 13 quasars by Bahcall et al. with the Faint Object Spectrograph on the Hubble Space Telescope as part of the Quasar Absorption Line Key Project. We estimate the mean intensity of ionizing radiation on the usual assumption that the proximity effect is caused entirely by the increased photoionization of absorbers near the quasars. The result is J(L) approximately 6 x 10(24) ergs s-1 cm-2 sr-1 Hz-1 at z almost-equal-to 0.5. However, the uncertainties are large, and even at the 1 sigma level, J(L) could be lower by a factor of 3 or higher by a factor of 6. Our estimate could be improved with a larger sample of absorbers and more accurate redshifts of a few of the quasars.
引用
收藏
页码:L63 / L66
页数:4
相关论文
共 32 条
[1]   REDSHIFT EVOLUTION OF THE LYMAN-LINE ABSORBING CLOUDS IN QUASAR SPECTRA [J].
ATWOOD, B ;
BALDWIN, JA ;
CARSWELL, RF .
ASTROPHYSICAL JOURNAL, 1985, 292 (01) :58-71
[2]   THE HUBBLE-SPACE-TELESCOPE QUASAR ABSORPTION-LINE KEY PROJECT .1. 1ST OBSERVATIONAL RESULTS, INCLUDING LYMAN-ALPHA AND LYMAN-LIMIT SYSTEMS [J].
BAHCALL, JN ;
BERGERON, J ;
BOKSENBERG, A ;
HARTIG, GF ;
JANNUZI, BT ;
KIRHAKOS, S ;
SARGENT, WLW ;
SAVAGE, BD ;
SCHNEIDER, DP ;
TURNSHEK, DA ;
WEYMANN, RJ ;
WOLFE, AM .
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, 1993, 87 (01) :1-43
[3]   QUASAR IONIZATION OF LYMN-ALPHA CLOUDS - THE PROXIMITY EFFECT, A PROBE OF THE ULTRAVIOLET BACKGROUND AT HIGH REDSHIFT [J].
BAJTLIK, S ;
DUNCAN, RC ;
OSTRIKER, JP .
ASTROPHYSICAL JOURNAL, 1988, 327 (02) :570-583
[4]  
BECHTOLD J, 1993, IN PRESS APJ
[5]  
BOCKHAREV NG, 1977, SOV ASTRON, V21, P542
[6]   REDDENINGS DERIVED FROM H-1 AND GALAXY COUNTS - ACCURACY AND MAPS [J].
BURSTEIN, D ;
HEILES, C .
ASTRONOMICAL JOURNAL, 1982, 87 (08) :1165-&
[7]   HIGH-RESOLUTION SPECTROSCOPY OF Q1100-264 AGAIN [J].
CARSWELL, RF ;
LANZETTA, KM ;
PARNELL, HC ;
WEBB, JK .
ASTROPHYSICAL JOURNAL, 1991, 371 (01) :36-48
[8]   HIGH-REDSHIFT QSO ABSORBING CLOUDS AND THE BACKGROUND IONIZING SOURCE [J].
CARSWELL, RF ;
WEBB, JK ;
BALDWIN, JA ;
ATWOOD, B .
ASTROPHYSICAL JOURNAL, 1987, 319 (02) :709-722
[9]   OBSERVATIONS OF THE SPECTRA OF Q0122-380 AND Q1101-264 [J].
CARSWELL, RF ;
WHELAN, JAJ ;
SMITH, MG ;
BOKSENBERG, A ;
TYTLER, D .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1982, 198 (01) :91-110
[10]  
CORBELLI E, 1993, PREPRINT