Speaker
Description
MAXI J1535-571 accretion flow exhibits optically thin (sub-Keplerian) and optically thick (Keplerian) plasma. The manifestation of soft photons and their interception and Comptonization by hot electrons produce hard X-rays, and cause the Compton cloud/post-shock region to change periodically. As a result, propagating oscillatory shock waves (Quasi-periodic oscillations; QPOs) were produced. The accretion flow geometry and the underlying physical mechanisms in the accretion flow are still debated. In this study, three X-ray missions’ datasets retrieved from the HEASARC were analyzed using HEASoft v6.28, the pipeline product software of each X-ray detector, and XSPEC v12.10.1f. The spectral fitting/modelling was done using a combination of accretion flow models. MAXI J1535-571 X-ray spectra and statistically significant correlated accretion flow parameters were obtained. The decrease in accretion rate ratio (ARR) from 1.443 to 0.946 and shock location from 56.21 rg to 46.48 rg (rg = gravitational radius) shows that the outburst progresses on timescales. A resonance condition of 0.62 – 0.79 and photon index of 2.0 – 2.4 indicates the presence of QPO in the accretion flow, and MAXI J1535-571 is in the hard-intermediate state. The QPO frequency of 1.70 – 1.96 Hz obtained is consistent with a type-C QPO. The variations of components of the accretion flow is responsible for the dynamical behavior of the accretion flow around the black hole. The geometry of MAXI J1535-571 during the studied epochs is a patchy-flaring turbulence flow. Hence, mass accretion rates are intrinsic properties of the accretion flow that cause a decrease in the ARR, which in turn is responsible for the delay in the transition period, the origin of the Γ-vQPO relation, and the flickering behavior of MAXI J1535-571.
Keywords: MAXI J1535-571; accretion flow, accretion rates, variations, dynamical behavior, geometry.
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