Energy dependent power spectral states and origin of aperiodic variability in black hole binaries

Abstract

We found the black hole candidate MAXI J1659-152 showed distinct power spectra, i.e., a power-law noise (PLN) vs. band-limited noise (BLN) plus quasi-periodic oscillations (QPOs), below and above about 2 keV respectively, in the observations with the Swift and the RXTE during the 2010 outburst, indicating a high energy cut-off of the PLN and a low energy cut-off of the BLN and the QPOs around 2 keV. The emergence of the PLN and the fading of the BLN and the QPOs initially took place from below 2 keV when the source entered the hard intermediate state and finally settled in the soft state three weeks later. The evolution was accompanied by the emergence of the disk spectral component and decreases in the amplitudes of variability in the soft X-ray and the hard X-ray bands. Our results indicate that the PLN is associated with the optically thick disk in both hard and intermediate states, and power spectral state is independent of the X-ray energy spectral state in a broadband view. We suggest that in the hard and the intermediate state, the BLN and the QPOs emerge from the innermost hot flow subjected to Comptonization, while the PLN originates from the optically thick disk further out. The energy cut-offs of the PLN and the BLN or QPOs then follow the temperature of the seed photons from the inner edge of the optically thick disk, while the high frequency cut-off of the PLN follows the orbital frequency at the inner edge of the optically thick disk as well.

5 pages, 6 figures, accepted for publication in ApJ

References in corpus (5)

• X-ray Properties of Black-Hole Binaries
• MAXI J1659-152: The shortest orbital period black-hole transient in outburst
• Spectral and Fourier analyses of X-ray QPO in accreting black holes
• Orbital Period and Outburst Luminosity of Transient Low Mass X-ray Binaries
• Combined Spectral and Timing Analysis of the Black Hole Candidate MAXI J1659-152 Discovered by MAXI and Swift

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• Detection of distinct power spectra in soft and hard X-ray bands in the hard state of GRS 1915+105
• Disc-corona interaction in the heartbeat state of GRS 1915+105
• Are spectral and timing correlations similar in different spectral states in black hole X-ray binaries?
• Swift X-ray Telescope study of the Black Hole Binary MAXI J1659-152: Variability from a two component accretion flow
• Inertial-Acoustic Oscillations of Black-Hole Accretion Discs with Large-Scale Poloidal Magnetic Fields
• Power spectral properties of the soft spectral states in four black hole transients