EXPLAINING THE SPECTRUM OF SAGITTARIUS-A-ASTERISK WITH A MODEL OF AN ACCRETING BLACK-HOLE

被引:445
作者
NARAYAN, R
YI, IS
MAHADEVAN, R
机构
[1] Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138
关键词
D O I
10.1038/374623a0
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
THE radio source at the centre of our Galaxy(1), Sagittarius A* (Sgr A*), seems to be a low-luminosity version of active galactic nuclei-a massive black hole that is accreting gas from the surrounding region(1,2). This idea is supported by observations of the gas and stars within 1 pc of Sgr A*, which appear to move under the influence of a large central mass(1,3,4). A recent determination of the upper limit(5,6) to the hard X-ray emission from the Galactic Centre has posed a problem for this picture, however, as the mass accretion rate implied by applying a standard accretion model to the X-ray data is far below that estimated from the observations of gas flows. Here we present a new model of accretion onto Sgr A*, in which most of the energy released is carried along with the gas and lost into the black hole of mass similar to 7 x 10(5) solar masses, rather than appearing as radiation. The model fits the observed spectrum of Sgr A* from radio to hard X-ray wavelengths, and reconciles the low observed luminosity with a high mass-accretion rate.
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收藏
页码:623 / 625
页数:3
相关论文
共 39 条
  • [1] SLIM ACCRETION DISKS
    ABRAMOWICZ, MA
    CZERNY, B
    LASOTA, JP
    SZUSZKIEWICZ, E
    [J]. ASTROPHYSICAL JOURNAL, 1988, 332 (02) : 646 - 658
  • [2] THERMAL EQUILIBRIA OF ACCRETION DISKS
    ABRAMOWICZ, MA
    CHEN, XM
    KATO, S
    LASOTA, JP
    REGEV, O
    [J]. ASTROPHYSICAL JOURNAL, 1995, 438 (01) : L37 - L39
  • [3] UPPER LIMIT OF 3.3 ASTRONOMICAL UNITS TO THE DIAMETER OF THE GALACTIC-CENTER RADIO-SOURCE SGR-A
    BACKER, DC
    ZENSUS, JA
    KELLERMANN, KI
    REID, M
    MORAN, JM
    LO, KY
    [J]. SCIENCE, 1993, 262 (5138) : 1414 - 1416
  • [4] THERMAL COUPLING OF IONS AND ELECTRONS BY COLLECTIVE EFFECTS IN 2-TEMPERATURE ACCRETION FLOWS
    BEGELMAN, MC
    CHIUEH, TH
    [J]. ASTROPHYSICAL JOURNAL, 1988, 332 (02) : 872 - 890
  • [5] DUSCHL WJ, 1994, ASTRON ASTROPHYS, V286, P431
  • [6] SPATIALLY RESOLVED NEAR-INFRARED EMISSION AND A BUBBLE OF HOT GAS IN THE CENTRAL ACTIVE REGION OF THE GALAXY
    ECKART, A
    GENZEL, R
    KRABBE, A
    HOFMANN, R
    VANDERWERF, PP
    DRAPATZ, S
    [J]. NATURE, 1992, 355 (6360) : 526 - 529
  • [7] FALCKE H, 1993, ASTRON ASTROPHYS, V278, pL1
  • [8] FALCKE H, 1993, ASTRON ASTROPHYS, V270, P102
  • [9] Frank J., 1992, ACCRETION POWER ASTR
  • [10] GENZEL R, 1987, ANNU REV ASTRON ASTR, V25, P377