Name: Divya Rawat
Affiliation: IUCAA
Conference ID : ASI2022_381
Title : The comptonizing medium of the black-hole X-ray binary MAXI J1535􀀀571 through type-C quasi-periodic oscillations
Authors : Divya Rawat, Mariano Mendez, Federico Garcia, Diego Altamirano, Konstantinos Karpouzas, Liang Zhang, Kevin Alabarta, Tomaso M. Belloni, Pankaj Jain, Candela Bellavita
Abstract Type: Oral
Abstract Category : Stars, ISM and Galaxy
Abstract : We report detailed spectral and temporal analysis results of the black-hole candidate MAXI J1535-571 using NICER observations in Sep-Oct 2017. We found type-C QPOs with frequency varying in the range 1.8-9.0 Hz when the source was in hard-intermediate state. We fit the rms and phase lag spectra of the QPO with a one-component Comptonisation model, which involves a structure made of an accretion disc and corona. We found that the size of the corona shrinks from 10^4 to 10^3 km. We note a change in the behaviour of the spectral and Comptonisation parameters when the QPO centroid frequency is above ~3.2 Hz, which we call critical frequency, (v_c). Also, the properties of the QPO and the time lag spectra at the QPO frequency show a change in correspondence to the QPO frequency reaching v_c. Interestingly, this critical frequency appears in the same period when emission of radio jet quenches for this source.