Astrosat view of GX 339-4 during the peak of the recent outburst
We present the spectral and timing analyses of \textit{AstroSat} observations of the Black Hole X-ray Binary GX 339-4 when the source was close the peak of the outburst in 2024. We find that both the spectral and timing variability of the source is indicative of it in its steep power law (SPL) state...
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Zusammenfassung: | We present the spectral and timing analyses of \textit{AstroSat} observations
of the Black Hole X-ray Binary GX 339-4 when the source was close the peak of
the outburst in 2024. We find that both the spectral and timing variability of
the source is indicative of it in its steep power law (SPL) state during the
observations. We used phenomenological and physical models to understand the
physics and geometry of accretion during this spectral state of the source.
Spectral fits indicate the presence of an accretion disc with a temperature of
$kT\sim$0.82 keV and a hot corona with a spectral index of $\sim$2.2 along with
a significant contribution from iron line emission from the accretion disc.
Strong QPOs were detected at $\sim$4.6 Hz in the Power Density Spectra of the
source along with a harmonics feature. Time and phase lag at the QPO frequency
are studied and we find a hard lag at the QPO frequency and at the same time a
soft lag at the harmonic frequency. We estimate the spin of the black hole and
it was found that $a = 0.99 \pm 0.003$. The height of the coronal region is
estimated to be about 2.5 $R_{g}$, which is found to be similar to that
observed during the previous outbursts of the source. We attempt to discuss the
possible physical scenario for the observed spectral and timing features
exhibited by the source. |
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DOI: | 10.48550/arxiv.2405.06090 |