Detection of high-frequency quasi-periodic oscillation during the reflare of MAXI J1348−630

Abstract

ABSTRACT In this work, we report the detection of high-frequency quasi-periodic oscillation (QPO) in the black hole X-ray binary MAXI J1348−630 in its hard spectral state. MAXI J1348−630 went through a reflare during MJD 58634 to MJD 58674 after a 104 d long outburst which began on MJD 58509. During the reflare, the binary system evolved through a series of hard states of varying luminosity. We detected a high-frequency QPO at 98.3 Hz with a significance of 3.7σ in one of the NICER observations during its evolution. It was argued that the QPO frequency might be related to the Keplerian frequency of the accretion flow at the inner radius around a Kerr black hole.