X-ray reflection in a sample of X-ray bright ultraluminous X-ray sources

被引:40
作者
Caballero-Garcia, M. D. [1 ]
Fabian, A. C. [1 ]
机构
[1] Univ Cambridge, Inst Astron, Cambridge CB3 0HA, England
关键词
black hole physics; line: formation; X-rays: galaxies; X-rays: general; XMM-NEWTON OBSERVATIONS; BLACK-HOLE; ACCRETION DISK; EMISSION; LINE; GALAXIES; SPIN; X-1;
D O I
10.1111/j.1365-2966.2009.16062.x
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We apply a reflection-based model to the best available XMM-Newton spectra of X-ray bright ultraluminous X-ray sources (NGC 1313 X-1, NGC 1313 X-2, M81 X-6, Holmberg IX X-1, NGC 5408 X-1 and Holmberg II X-1). A spectral drop is apparent in the data of all the sources at energies 6-7 keV. The drop is interpreted here in terms of relativistically blurred ionized reflection from the accretion disc. A soft excess is also detected from these sources [as usually found in the spectra of active galactic nuclei (AGN)], with emission from O K and Fe L, in the case of NGC 5408 X-1 and Holmberg II X-1, which can be understood as features arising from reflection of the disc. Remarkably, ionized disc reflection and the associated power-law continuum provide a good description of the broad-band spectrum, including the soft excess. There is no requirement for thermal emission from the inner disc in the description of the spectra. The black holes of these systems must then be highly spinning, with a spin close to the maximum rate of a maximal spinning black hole. The results require the action of strong light bending in these sources. We suggest that they could be strongly accreting black holes in which most of the energy is extracted from the flow magnetically and released above the disc thereby avoiding the conventional Eddington limit.
引用
收藏
页码:2559 / 2566
页数:8
相关论文
共 51 条
[1]   Spectroscopy of Optical Counterparts of Ultraluminous X-Ray Sources [J].
Abolmasov, P. ;
Fabrika, S. ;
Sholukhova, O. ;
Afanasiev, V. .
ASTROPHYSICAL BULLETIN, 2007, 62 (01) :36-51
[2]  
Arnaud KA, 1996, ASTR SOC P, V101, P17
[3]   ELECTROMAGNETIC EXTRACTION OF ENERGY FROM KERR BLACK-HOLES [J].
BLANDFORD, RD ;
ZNAJEK, RL .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1977, 179 (02) :433-456
[4]   Constraining black hole spin via X-ray spectroscopy [J].
Brenneman, Laura W. ;
Reynolds, Christopher S. .
ASTROPHYSICAL JOURNAL, 2006, 652 (02) :1028-1043
[5]   A theory of gamma-ray bursts [J].
Brown, GE ;
Lee, CH ;
Wijers, RAMJ ;
Lee, HK ;
Israelian, G ;
Bethe, HA .
NEW ASTRONOMY, 2000, 5 (04) :191-210
[6]   Relativistic iron emission lines in neutron star low-mass X-ray binaries as probes of neutron star radii [J].
Cackett, Edward M. ;
Miller, Jon M. ;
Bhattacharyya, Sudip ;
Grindlay, Jonathan E. ;
Homan, Jeroen ;
Van Der Klis, Michiel ;
Miller, M. Coleman ;
Strohmayer, Tod E. ;
Wijnands, Rudy .
ASTROPHYSICAL JOURNAL, 2008, 674 (01) :415-420
[7]   The nature of accreting black holes in nearby galaxy nuclei [J].
Colbert, EJM ;
Mushotzky, RF .
ASTROPHYSICAL JOURNAL, 1999, 519 (01) :89-107
[8]   Quasi-periodic oscillations and strongly comptonized X-ray emission from Holmberg IX X-1 [J].
Dewangan, GC ;
Griffiths, RE ;
Rao, AR .
ASTROPHYSICAL JOURNAL, 2006, 641 (02) :L125-L128
[9]   H I IN THE GALAXY [J].
DICKEY, JM ;
LOCKMAN, FJ .
ANNUAL REVIEW OF ASTRONOMY AND ASTROPHYSICS, 1990, 28 :215-261
[10]  
FABBIANO G, 1989, ANNU REV ASTRON ASTR, V27, P87