High-Frequency Quasi-Periodic Oscillations in black-hole binaries

TL;DR

This study analyzed extensive X-ray data from 22 black-hole transients to detect high-frequency QPOs, confirming some known frequencies and exploring their characteristics, with implications for future X-ray timing missions.

Contribution

It provides a homogeneous analysis of a large dataset, confirming known high-frequency QPOs and refining their frequency distributions in black-hole binaries.

Findings

11 high-frequency QPO detections from two sources

QPO frequencies clustered around 180 Hz and 280 Hz for XTE J1550-564

Less sharp dichotomy in frequencies for GRO J1655-40

Abstract

We present the results of the analysis of a large database of X-ray observations of 22 galactic black-hole transients with the Rossi X-Ray timing explorer throughout its operative life for a total exposure time of ~12 Ms. We excluded persistent systems and the peculiar source GRS 1915+105, as well as the most recently discovered sources. The semi-automatic homogeneous analysis was aimed at the detection of high-frequency (100-1000 Hz) quasi-periodic oscillations (QPO), of which several cases were previously reported in the literature. After taking into account the number of independent trials, we obtained 11 detections from two sources only: XTE J1550-564 and GRO J1655-40. For the former, the detected frequencies are clustered around 180 Hz and 280 Hz, as previously found. For the latter, the previously-reported dichotomy 300-450 Hz is found to be less sharp. We discuss our results in comparison with kHz QPO in neutron-star X-ray binaries and the prospects for future timing X-ray missions.