IDENTIFICATION OF THE X-RAY THERMAL DOMINANT STATE IN AN ULTRALUMINOUS X-RAY SOURCE IN M82

Journal Article · Thu Apr 01 04:00:00 EDT 2010 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/712/2/L169; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21305063

Hua, Feng ^[1]; Kaaret, Philip ^[2]

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1. Department of Engineering Physics and Center for Astrophysics, Tsinghua University, Beijing 100084 (China)
2. Department of Physics and Astronomy, University of Iowa, Van Allen Hall, Iowa City, IA 52242 (United States)

The thermal dominant state in black hole binaries (BHBs) is well understood but rarely seen in ultraluminous X-ray sources (ULXs). Using simultaneous observations of M82 with Chandra and XMM-Newton, we report the first likely identification of the thermal dominant state in a ULX based on the disappearance of X-ray oscillations, low timing noise, and a spectrum dominated by multicolor disk emission with luminosity varying to the fourth power of the disk temperature. This indicates that ULXs are similar to Galactic BHBs. The brightest X-ray spectrum can be fitted with a relativistic disk model with either a highly super-Eddington (L {sub disk}/L {sub Edd} = 160) non-rotating black hole (BH) or a close to Eddington (L {sub disk}/L {sub Edd} {approx} 2) rapidly rotating BH. The latter interpretation is preferred, due to the absence of such highly super-Eddington states in Galactic BHs and active galactic nuclei, and suggests that the ULX in M82 contains a BH of 200-800 solar masses with nearly maximal spin. On long timescales, the source normally stays at a relatively low flux level with a regular 62-day orbital modulation and occasionally exhibits irregular flaring activity. These thermal dominant states are observed during outbursts.

• OSTI ID: 21305063
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 2 Vol. 712; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
99 GENERAL AND MISCELLANEOUS
ACCRETION DISKS
BLACK HOLES
COSMIC X-RAY SOURCES
EMISSION
FLARING
GALAXY NUCLEI
LUMINOSITY
MASS
RELATIVISTIC RANGE
SPIN
X-RAY SPECTRA