ON THE GEOMETRY OF THE X-RAY-EMITTING REGION IN SEYFERT-GALAXIES

被引:216
作者
STERN, BE
POUTANEN, J
SVENSSON, R
SIKORA, M
BEGELMAN, MC
机构
[1] STOCKHOLM OBSERV,S-13336 SALTSJOBADEN,SWEDEN
[2] NICHOLAS COPERNICUS ASTRON CTR,PL-00716 WARSAW,POLAND
[3] UNIV COLORADO,JOINT INST LAB ASTROPHYS,BOULDER,CO 80309
[4] UNIV COLORADO,DEPT ASTROPHYS PLANETARY & ATMOSPHER SCI,BOULDER,CO 80309
关键词
ACCRETION; ACCRETION DISKS; GALAXIES; SEYFERT; GAMMA RAYS; THEORY; RADIATION; MECHANISMS; THERMAL; RADIATIVE TRANSFER; X-RAYS; GENERAL;
D O I
10.1086/309617
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
For the first time, detailed radiative transfer calculations of Comptonized X-ray and gamma-ray radiation in a hot pair plasma above a cold accretion disk are performed using two independent codes and methods. The simulations include both energy and pair balance as well as reprocessing of the X- and gamma-rays by the cold disk. We study both plane-parallel coronae as well as active dissipation regions having shapes of hemispheres and pill boxes located on the disk surface. It is shown, contrary to earlier claims, that plane-parallel coronae in pair balance have difficulties in self-consistently reproducing the ranges of 2-20 keV spectral slopes, high-energy cutoffs, and compactnesses inferred from observations of type 1 Seyfert galaxies. Instead, the observations are consistent with the X-rays coming from a number of individual active regions located on the surface of the disk. A number of effects such as anisotropic Compton scattering, the reflection hump, feedback to the soft photon source by reprocessing, and an active region in pair equilibrium all conspire to produce the observed ranges of X-ray slopes, high-energy cutoffs, and compactnesses. The spread in spectral X-ray slopes can be caused by a spread in the properties of the active regions such as their compactnesses and their elevations above the disk surface. Simplified models invoking isotropic Comptonization in spherical clouds are no longer sufficient when interpreting the data.
引用
收藏
页码:L13 / L17
页数:5
相关论文
共 26 条
  • [1] THE BEHAVIOR OF COMPACT NON-THERMAL SOURCES WITH PAIR PRODUCTION
    DONE, C
    FABIAN, AC
    [J]. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1989, 240 (01) : 81 - 102
  • [2] STRUCTURED CORONAE OF ACCRETION DISKS
    GALEEV, AA
    ROSNER, R
    VAIANA, GS
    [J]. ASTROPHYSICAL JOURNAL, 1979, 229 (01) : 318 - 326
  • [3] ANISOTROPIC COMPTONIZATION IN THERMAL PLASMAS - SPECTRAL DISTRIBUTION IN PLANE-PARALLEL GEOMETRY
    HAARDT, F
    [J]. ASTROPHYSICAL JOURNAL, 1993, 413 (02) : 680 - 693
  • [4] HAARDT F, 1991, ASTROPHYS J, V380, pL51, DOI 10.1086/186171
  • [5] X-RAY-SPECTRA FROM 2-PHASE ACCRETION DISKS
    HAARDT, F
    MARASCHI, L
    [J]. ASTROPHYSICAL JOURNAL, 1993, 413 (02) : 507 - 517
  • [6] A MODEL FOR THE X-RAY AND ULTRAVIOLET EMISSION FROM SEYFERT-GALAXIES AND GALACTIC BLACK-HOLES
    HAARDT, F
    MARASCHI, L
    GHISELLINI, G
    [J]. ASTROPHYSICAL JOURNAL, 1994, 432 (02) : L95 - L99
  • [7] HAARDT F, 1994, THESIS SISSA TRIESTE
  • [8] JOINT ROSAT-COMPTON GRO OBSERVATIONS OF THE X-RAY-BRIGHT SEYFERT-GALAXY IC-4329A
    MADEJSKI, GM
    ZDZIARSKI, AA
    TURNER, TJ
    DONE, C
    MUSHOTZKY, RF
    HARTMAN, RC
    GEHRELS, N
    CONNORS, A
    FABIAN, AC
    NANDRA, K
    CELOTTI, A
    REES, MJ
    JOHNSON, WN
    GROVE, JE
    STARR, CH
    [J]. ASTROPHYSICAL JOURNAL, 1995, 438 (02) : 672 - 679
  • [9] OSSE OBSERVATIONS OF NGC-4151
    MAISACK, M
    JOHNSON, WN
    KINZER, RL
    STRICKMAN, MS
    KURFESS, JD
    CAMERON, RA
    JUNG, GV
    GRABELSKY, DA
    PURCELL, WR
    ULMER, MP
    [J]. ASTROPHYSICAL JOURNAL, 1993, 407 (02) : L61 - L64
  • [10] GINGA OBSERVATIONS OF THE X-RAY-SPECTRA OF SEYFERT-GALAXIES
    NANDRA, K
    POUNDS, KA
    [J]. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1994, 268 (02) : 405 - 429