Speaker
Description
We present the results from X-ray broadband spectro-temporal analyses of recurrent outbursting sources GX 339$-$4 and H 1743$-$322 using AstroSat and NuSTAR archival observations carried out during $2016-2022$. GX 339$-$4 was found to be making transition from quiescence to outburst, and the wide-band spectral analyses results during outbursts shows that GX 339$-$4 was in hard ($kT_{\rm {bb}}=0.29-0.51$ keV, $\Gamma=1.46-2.06$ and $L_{\rm bol} =0.27-8.22 \%$ of Eddington luminosity $L_{\rm Edd}$), intermediate ($kT_{\rm {in}}=0.75-1.08$ keV, $\Gamma=1.71-2.49$, $L_{\rm {bol}}=6.74-9.11 \% \,L_{\rm Edd}$) and soft states ($kT_{\rm {in}}=0.51-0.93$ keV, $\Gamma=1.67-3.74$, $L_{\rm {bol}}=9.06-15.27 \% \,L_{\rm Edd}$). Instead H 1743$-$322 found to make transition from quiscence to only hard state ($\Gamma=1.57-1.73$, $L_{\rm {bol}}=3.07-6.61 \% \,L_{\rm Edd}$). Timing variability studies revealed the presence of Quasi-periodic Oscillations (QPOs) in GX 339$-$4 with frequencies varying between $0.10 - 5.37$ Hz along with harmonics. We detect type C QPOs in H 1743$-$322 with frequencies in the range $0.22 - 1.01$ Hz along with distinct harmonics. The energy dependent power density spectral study shows that, in GX 339$-$4 fundamental QPO and harmonics are present only in $3-20$ keV. Whereas in H 1743$-$322, the fundamental QPO is present only in $3-40$ keV energy band and the harmonic is not significant above $\sim 20$ keV. We discuss these observational findings in the context of accretion dynamics around black hole binary.
| Presentation Type | Oral |
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