Abstract Details

Name: Sneha Prakash Mudambi
Affiliation: CHRIST (Deemed to be University), Bengaluru
Conference ID: ASI2020_141
Title : Spectro-timing properties of MAXI J1820+070 during rising phase of its outburst using AstroSat
Authors and Co-Authors : M. Sneha Prakash (1), S. B. Gudennavar (1), M. Bari (2), R. Misra (2) , S. G. Bubbly (1) and J.S. Yadav (3) (1) Department of Physics and Electronics, CHRIST (Deemed to be University), Hosur Road, Bengaluru-560029, India. (2) Inter-University Centre for Astronomy and Astrophysics, Ganeshkind, Pune-411007, India. (3) Department of Physics, Indian Institute of Technology, Kanpur,-208016 India.
Abstract Type : Oral
Abstract Category : Stars, ISM and Galaxy
Abstract : MAXI J820+070, the brightest X-ray novae discovered till date, was first detected in optical on 6th March by ASSASSN survey and later in X-rays on 11 March 2018 by MAXI mission. Low inclination angle (~ 30°), proximity of the source (~ 3.46 kpc) and high X-ray flux rate (~108 erg cm2s1) provided a unique opportunity to study the physics of accretion with great detail. The yearlong outburst of the source was captured by several leading missions, including our own AstroSat. In this work, we present for the first time the broad band spectral and temporal analysis results of AstroSat’s observations of MAXI J1820+070 on 30th and 31st March 2018, during the rising phase of its outburst. The combined SXT and LAXPC spectrum was modelled using thermal Comptonization along with disk blackbody and reflection components. Spectral analysis revealed that the source was in its hard-spectral state (Γ = 1.61) and with a cool accretion disk (kTin= 0.22) truncated at a large distance. Power density spectra showed a presence of a quasi-periodic oscillation (QPO) at 47.7 mHz and this is the first confirmed report of the type C QPO for this source. Temporal analysis in the energy range 3.0 - 50.0 keV has revealed frequency dependent hard lags of the order of 100 millisecond. In addition to this, we have modelled the single temperature stochastic propagation model proposed by Maqbool et al., (MNRAS, 486, 2964, 2019) to the observed energy dependent time-lags and fractional rms and found that the predictions of the model match well with observations.