<i>NICER</i> uncovers the transient nature of the type-B quasi-periodic oscillation in the black hole candidate MAXI J1348−630
Liang Zhang, D. Altamirano, P. Uttley, Federico García, Mariano Méndez, J. Homan, James F. Steiner, Kevin Alabarta, D. J. K. Buisson, Ronald A. Remillard, Keith C. Gendreau, Zaven Arzoumanian, C. B. Markwardt, Tod E. Strohmayer, Joey Neilsen, Arkadip Basak
Abstract
ABSTRACT We present a systematic spectral-timing analysis of a fast appearance/disappearance of a type-B quasi-periodic oscillation (QPO), observed in four Neutron Star Interior Composition Explorer (NICER) observations of MAXI J1348−630. By comparing the spectra of the period with and without the type-B QPO, we found that the main difference appears at energy bands above ∼2 keV, suggesting that the QPO emission is dominated by the hard Comptonized component. During the transition, a change in the relative contribution of the disc and Comptonized emission was observed. The disc flux decreased while the Comptonized flux increased from non-QPO to type-B QPO. However, the total flux did not change too much in the NICER band. Our results reveal that the type-B QPO is associated with a redistribution of accretion power between the disc and Comptonized emission. When the type-B QPO appears, more accretion power is dissipated into the Comptonized region than in the disc. Our spectral fits give a hint that the increased Comptonized emission may come from an additional component that is related to the base of the jet.