Do the broad emission line clouds see the same continuum that we see?

被引:85
作者
Korista, K [1 ]
Ferland, G [1 ]
Baldwin, J [1 ]
机构
[1] ASSOC UNIV RES ASTRON INC,CERRO TOLOLO INTER AMER OBSERV,LA SERENA,CHILE
关键词
line; formation; quasars; emission lines; ultraviolet; galaxies;
D O I
10.1086/304659
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Recent observations of quasars, Mrk 335 and the HST quasar composite spectrum, have indicated that many quasars have remarkably soft ionizing continua (f(v) proportional to v(-2), 13.6-100 eV). We point out that the number of photons with hv > 54.4 eV is insufficient to create the observed strengths of the He II emission lines. While the numbers of photons which energize C IV lambda 1549 and O VI lambda 1034 are sufficient, even the most efficiently emitting clouds for these two lines must each cover at least 20%-40% of the source. If the typical quasar ionizing continuum is indeed this soft, then we must conclude that the broad emission line clouds must see a very different (harder) continuum than we see. The other viable possibility is that the W-EUV SED is double peaked, with the second peaking near 54 eV, its Wien tail being the observed soft X-ray excess.
引用
收藏
页码:555 / 559
页数:5
相关论文
共 53 条
[21]  
JOLY M, 1987, ASTRON ASTROPHYS, V184, P33
[22]   Broad emission-line variability in Markarian 335 [J].
Kassebaum, TM ;
Peterson, BM ;
Wanders, I ;
Pogge, RW ;
Bertram, R ;
Wagner, RA .
ASTROPHYSICAL JOURNAL, 1997, 475 (01) :106-117
[23]   THE ULTRAVIOLET-SPECTRA OF INTERMEDIATE-REDSHIFT QUASARS [J].
KINNEY, AL ;
HUGGINS, PJ ;
BREGMAN, JN ;
GLASSGOLD, AE .
ASTROPHYSICAL JOURNAL, 1985, 291 (01) :128-135
[24]  
KORATKAR A, 1990, THESIS U MICHIGAN
[25]   SEARCH FOR PARTIAL SYSTEMIC LYMAN EDGES IN NEARBY QUASARS [J].
KORATKAR, AP ;
KINNEY, AL ;
BOHLIN, RC .
ASTROPHYSICAL JOURNAL, 1992, 400 (02) :435-459
[26]   An atlas of computed equivalent widths of quasar broad emission lines [J].
Korista, K ;
Baldwin, J ;
Ferland, G ;
Verner, D .
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, 1997, 108 (02) :401-415
[27]   STEPS TOWARD DETERMINATION OF THE SIZE AND STRUCTURE OF THE BROAD-LINE REGION IN ACTIVE GALACTIC NUCLEI .8. AN INTENSIVE HST, IUE, AND GROUND-BASED STUDY OF NGC-5548 [J].
KORISTA, KT ;
ALLOIN, D ;
BARR, P ;
CLAVEL, J ;
COHEN, RD ;
CRENSHAW, DM ;
EVANS, IN ;
HORNE, K ;
KORATKAR, AP ;
KRISS, GA ;
KROLIK, JH ;
MALKAN, MA ;
MORRIS, SL ;
NETZER, H ;
OBRIEN, PT ;
PETERSON, BM ;
REICHERT, GA ;
RODRIGUEZPASCUAL, PM ;
WAMSTEKER, W ;
ANDERSON, KSJ ;
AXON, DJ ;
BENITEZ, E ;
BERLIND, P ;
BERTRAM, R ;
BLACKWELL, JH ;
BOCHKAREV, NG ;
BOISSON, C ;
CARINI, M ;
CARRILLO, R ;
CARONE, TE ;
CHENG, FZ ;
CHRISTENSEN, JA ;
CHUVAEV, KK ;
DIETRICH, M ;
DOKTER, JJ ;
DOROSHENKO, V ;
DULTZINHACYAN, D ;
ENGLAND, MN ;
ESPEY, BR ;
FILIPPENKO, AV ;
GASKELL, CM ;
GOAD, MR ;
HO, LC ;
HUCHRA, JP ;
JIANG, XJ ;
KASPI, S ;
KOLLATSCHNY, W ;
LAOR, A ;
LUMINET, JP ;
MACALPINE, GM .
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, 1995, 97 (02) :285-330
[28]   THE EFFECTS OF THERMAL ACCRETION DISK SPECTRA ON THE EMISSION-LINES FROM ACTIVE GALACTIC NUCLEI [J].
KROLIK, JH ;
KALLMAN, TR .
ASTROPHYSICAL JOURNAL, 1988, 324 (02) :714-720
[29]   THE SPECTRAL ENERGY-DISTRIBUTION OF THE Z=3 QUASAR - HS-1946+7658 [J].
KUHN, O ;
BECHTOLD, J ;
CUTRI, R ;
ELVIS, M ;
RIEKE, M .
ASTROPHYSICAL JOURNAL, 1995, 438 (02) :643-649
[30]   The soft X-ray properties of a complete sample of optically selected quasars .2. Final results [J].
Laor, A ;
Fiore, F ;
Elvis, M ;
Wilkes, BJ ;
McDowell, JC .
ASTROPHYSICAL JOURNAL, 1997, 477 (01) :93-113