Weakly broadened iron line in the X-ray spectrum of the Ultra Luminous X-ray source M82 X-1

Abstract

In this paper we present the best quality XMM-Newton and Suzaku data from M82 X-1 so far. We analyze the spectra of this remarkable Ultra-Luminous X-ray Source in a self-consistent manner. We have disentangled emission from the host galaxy, responsible for the soft X-ray emission (E<2.5 keV), which is successfully described by a two-temperature thermal emission from a hot plasma in multi-phase state, plus a narrow Fe line emission at 6.7 keV. This allowed us to properly study the intrinsic continuum emission from M82 X-1. The continuum of the Suzaku spectrum is curved and the high quality data of the Suzaku spectrum allowed us to significantly detect a weakly broadened Fe K-alpha emission line. The Equivalent-Width is in the range 30-80 eV and it does not depend on the model applied for the continuum. Assuming that this line is coming from the ULX via disc fluorescence, the data indicates a disc truncation at a radius of 6-20 gravitational radii. This value is comparable to or even larger than the Innermost Stable Circular Orbit of a non-spinning (Schwarzschild) black hole. Future longer observations might test this scenario.

Accepted (09/08/2011) for publication in MNRAS. (7 pages, including 6 figures and 3 tables)

References in corpus (8)

• XMM-Newton observations of the brightest Ultraluminous X-ray sources
• Iron line and diffuse hard X-ray emission from the starburst galaxy M82
• FERO: Finding Extreme Relativistic Objects. I. Statistics of Relativistic Fe Kalpha lines in Radio-Quiet Type 1 AGN
• A 62 Day X-Ray Periodicity and an X-Ray Flare from the Ultraluminous X-Ray Source in M82
• A deep X-ray observation of M82 with XMM-Newton
• Identification of the X-Ray Thermal Dominant State in an Ultraluminous X-Ray Source in M82
• Suzaku Discovery of a Hard Component Varying Independently of the Power-Law Emission in MCG-6-30-15
• Long-Term Spectral Variations of Ultraluminous X-ray Sources in the Interacting Galaxy Systems M51 and NGC4490/85

Cited by in corpus (7)

• A study of X-ray emission of galaxies hosting molecular outflows (MOX sample)
• Quasi-Periodic Oscillations and energy spectra from the two brightest Ultra-Luminous X-ray sources in M82
• Can the 62 day X-ray period of the Ultraluminous X-ray source M82 X-1 be due to a precessing accretion disk?
• On the Nature of the mHz X-Ray Quasi-periodic Oscillations from Ultraluminous X-Ray Source M82 X-1: Search for Timing-Spectral Correlations
• X-ray spectral cut-off and the lack of hard X-ray emission from two ultraluminous X-ray sources M81 X-6 and Holmberg IX X-1
• Evidence for Fe K${}_{\alpha }$ line and soft X-ray lag in NGC 7456 ULX-1
• Spectral analysis of ultraluminous X-ray pulsars with models of X-ray pulsars