Flux and spectral variations of 1E${\thinspace}$1740.7$-$2942 over the years 2003$-$2012

TL;DR

This study analyzes 10 years of X-ray observations of the black hole system 1E1740.7-2942, revealing spectral variations, plasma temperature range, and tentative periodicities in its flux.

Contribution

It provides a long-term spectral and flux variability analysis of 1E1740.7-2942 using INTEGRAL data, including spectral modeling and periodogram analysis.

Findings

Plasma temperature varies between 20 and 90 keV.

Average power-law index is 1.41.

Tentative periods at 2.90 and 3.99 days.

Abstract

The black hole system 1E${\thinspace}$1740.7$-$2942 is usually the brightest hard X-ray source (above 20 keV) near the Galactic Center, but presents some epochs of low emission (below the INTEGRAL detection limit, for example). In this work, we present the results of studies on 1E${\thinspace}$1740.7$-$2942 over 10 years, using the instruments ISGRI/IBIS and JEM-X, both on board the INTEGRAL observatory. We fit the spectra with both the compTT and cutoffpl models. According to the fits and taking the mean value over the 10 years, we have obtained a plasma temperature in the range $\sim$20$\,-\,$90$\thinspace$ keV, and an average powerlaw index of 1.41 ($\sigma$=0.25). We have also made a Lomb$\,-\,$Scargle periodogram of the flux in the 50$\,-\,$20${\thinspace}$keV band and found two tentative periods at 2.90 and 3.99${\thinspace}$days. We present here the preliminary results of this ongoing work.