The black hole candidate MAXI J1659-152: spectral and timing analysis during its 2010 outburst

TL;DR

This study provides a detailed spectral and timing analysis of MAXI J1659-152 during its 2010 outburst, revealing how different emission components influence variability and state transitions in black hole transients.

Contribution

It offers a comprehensive spectral-timing analysis of MAXI J1659-152's 2010 outburst, highlighting the evolution of variability and emission components during state changes.

Findings

Hard emission drives fast variability and is quenched during type-B oscillations.

Count-rate peaks are initially due to both disc and hard emission, then only hard emission in the soft state.

Time-lags between soft and hard X-ray variability are larger during the hard-to-soft transition.

Abstract

We present a comprehensive spectral-timing study of the black hole candidate MAXI J1659-152 during its 2010 outburst. We analysed 65 RXTE observations taken along this period and computed the fundamental diagrams commonly used to study black hole transients. We fitted power density and energy spectra and studied the evolution of the spectral and timing parameters along the outburst. We discuss the evolution of the variability observed at different energy bands on the basis of the relative contribution of the disc and hard components to the energy spectrum of the source. We conclude that hard emission accounts for the observed fast variability, it being strongly quenched when type-B oscillations are observed. We find that both disc and hard emission are responsible for local count-rate peaks until the system reaches the soft state. From that point, the peaks are only observed in the hard component, whereas the thermal component drops monotonically probably following the accretion rate decrease. We have also computed time-lags between soft and hard X-ray variability confirming that lags are larger during the hard-to-soft transition than during the hard state.