We present the results obtained from detailed timing and spectral studies of a black hole candidate MAXI J1813-095 using Swift,NICER,and NuSTAR observations during its 2018 outburst.The timing behavior of the source i...We present the results obtained from detailed timing and spectral studies of a black hole candidate MAXI J1813-095 using Swift,NICER,and NuSTAR observations during its 2018 outburst.The timing behavior of the source is mainly studied by examining NICER light curves in the 0.5−10 keV range.We did not find any signature of quasi-periodic oscillations in the power density spectra of the source.We carry out spectral analysis with a combined disk blackbody&power law model,and physical two-component advective flow(TCAF)model.From the combined disk blackbody&power-law model,we extracted thermal and non-thermal fluxes,photon index and inner disk temperature.We also find evidence for weak reflection in the spectra.We have tested the physical TCAF model on a broadband spectrum from NuSTAR and Swift/XRT.The parameters like mass accretion rates,the size of Compton clouds and the shock strength are extracted.Our result affirms that the source remained in the hard state during the entire outburst which indicates a‘failed’outburst.We estimate the mass of the black hole as 7.4±1.5M⊙from the spectral study with the TCAF model.We apply the LAOR model for the Fe K line emission.From this,the spin parameter of the black hole is ascertained as a^(∗)>0.76.The inclination angle of the system is estimated to be in the range of 28°−45°from the reflection model.We find the source distance to be∼6 kpc.展开更多
基金This research has made use of data and/or software provided by the High Energy Astrophysics Science Archive Research Center(HEASARC)which is a service of the Astrophysics Science Division at NASA/GSFC and the High Energy Astrophysics Division of the Smithsonian Astrophysical Observatory+5 种基金This research has made use of the NuSTAR Data Analysis Software(NuSTARDAS)jointly developed by the ASI Science Data Center(ASDC,Italy)California Institute of Technology(Caltech,USA)This work has made use of XRT data supplied by the UK Swift Science Data Centre at the University of Leicester,UK.A.J.and N.K.acknowledge support from the research fellowship from Physical Research Laboratory,Ahmedabad,Indiafunded by the Department of Space,Government of India for this work.K.C.acknowledges support from the DST/INSPIRE Fellowship(IF170233)R.B.acknowledges support from the CSIR-UGC NET qualified UGC fellowship(June-2018,527223)Research by S.K.C.and D.D.is supported in part by the Higher Education Dept.of the Govt.of West Bengal,India.S.K.C.and D.D.also acknowledge partial support from ISRO sponsored RESPOND project(ISRO/RES/2/418/17-18)fund.H.-K.C.is supported by MOST of Taiwan under grants MOST/106-2923-M-007-002-MY3 and MOST/108-2112-M-007-003.D.D.acknowledges support from DST/GITA sponsored India-Taiwan collaborative project(GITA/DST/TWN/P-76/2017)fund.
文摘We present the results obtained from detailed timing and spectral studies of a black hole candidate MAXI J1813-095 using Swift,NICER,and NuSTAR observations during its 2018 outburst.The timing behavior of the source is mainly studied by examining NICER light curves in the 0.5−10 keV range.We did not find any signature of quasi-periodic oscillations in the power density spectra of the source.We carry out spectral analysis with a combined disk blackbody&power law model,and physical two-component advective flow(TCAF)model.From the combined disk blackbody&power-law model,we extracted thermal and non-thermal fluxes,photon index and inner disk temperature.We also find evidence for weak reflection in the spectra.We have tested the physical TCAF model on a broadband spectrum from NuSTAR and Swift/XRT.The parameters like mass accretion rates,the size of Compton clouds and the shock strength are extracted.Our result affirms that the source remained in the hard state during the entire outburst which indicates a‘failed’outburst.We estimate the mass of the black hole as 7.4±1.5M⊙from the spectral study with the TCAF model.We apply the LAOR model for the Fe K line emission.From this,the spin parameter of the black hole is ascertained as a^(∗)>0.76.The inclination angle of the system is estimated to be in the range of 28°−45°from the reflection model.We find the source distance to be∼6 kpc.
