Observations of AR Sco with $Chandra$ and $AstroSat$ Soft X-ray Telescope

TL;DR

This study presents simultaneous soft X-ray observations of the binary system AR Sco with AstroSat and Chandra, revealing consistent flux levels and spectral properties, with minimal modulation and a stable two-temperature plasma model.

Contribution

First simultaneous soft X-ray observations of AR Sco with AstroSat and Chandra, providing insights into its spectral stability and flux consistency over time.

Findings

X-ray flux consistent across AstroSat and Chandra observations

Flux slightly lower than previous XMM-Newton measurements

Spectral analysis supports a two-temperature plasma model

Abstract

We present our $AstroSat$ soft X-ray observations of a compact binary system, AR Sco, and analysis of its X-ray observations with $Chandra$ that were taken only about a week before the $AstroSat$ observations. An analysis of the soft X-ray ($0.3-2.0$ keV) data limits the modulation of the spin, orbital, or beat periods to less than 0.03 counts s$^{-1}$ or $<$10\% of the average count rate. The X-ray flux obtained from both observatories is found to be almost identical (within a few percent) in flux, and about 30\% lower than reported from the nine months older observations with $XMM-Newton$. A two-temperature thermal plasma model with the same spectral parameters fit $Chandra$ and $AstroSat$ data very well, and requires very little absorption in the line of sight to the source. The low-temperature component has the same temperature ($\sim$1 keV) as reported earlier, but the high-temperature component has a lower temperature of 5.0$^{+0.8}_{-0.7}$ keV as compared to 8.0 keV measured earlier, however, the difference is not statistically significant.