Unveiling the high energy tail of 1E 1740.7-2942 with INTEGRAL

Abstract

The microquasar 1E 1740.7-2942 is observed with Integral since Spring 2003. Here, we report on the source high energy behaviour by using the first three years of data collected with SPI and IBIS telescopes, taking advantage of the instruments complementarity. Light curves analysis showed two main states for 1E 1740.7-2942: the canonical low/hard state of black-hole candidates and a ``dim'' state, characterised by a ~ 20 times fainter emission, detected only below 50 keV and when summing more than 1Ms of data. For the first time the continuum of the low/hard state has been measured up to ~ 600 keV with a spectrum that is well represented by a thermal Comptonization plus an additional component necessary to fit the data above 200 keV. This high energy component could be related to non-thermal processes as already observed in other black-hole candidates. Alternatively, we show that a model composed by two thermal Comptonizations provides an equally representative description of the data: the temperature of the first population of electrons results as (kTe)_1 ~ 30 keV while the second, (kTe)_2, is fixed at 100 keV. Finally, searching for 511 keV line showed no feature, either narrow or broad, transient or persistent.

arXiv commentaccepted in Astrophysical Journal Part 1; 3 figures

References in corpus (20)

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• NuSTAR and INTEGRAL observations of a low/hard state of 1E1740.7-2942
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• The Accreting Black Hole Swift J1753.5-0127 from Radio to Hard X-Ray
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• Broadband X-ray analysis of 1E 1740.7-2942: constraints on spin, inclination and a tentative black hole mass
• Confirming the thermal Comptonization model for black hole X-ray emission in the low-hard state
• First Results from Fermi GBM Earth Occultation Monitoring: Observations of Soft Gamma-Ray Sources Above 100 keV
• Search for Outbursts in the Narrow 511-keV Line from Compact Sources Based on INTEGRAL Data
• Suzaku Observations of the Galactic Center Microquasar 1E 1740.7-2942
• Suzaku Observations of the Great Annihilator and the Surrounding Diffuse Emissions
• Hard X-ray Tail Discovered in the Clocked Burster GS 1826-238
• Finding persistent sources with the BeppoSAX/WFC: a in-depth analysis
• MAXI J1535-571 2017 outburst Seen by INTEGRAL/SPI and Investigating the Origin of Its Hard Tail
• Comptonization in 1E 1740.7-2942 spectra from 2 to 200 keV
• Long-Term Monitoring of the Black Hole Candidate Swift J1753.5-0127 with INTEGRAL/SPI
• Flux and spectral variations of 1E1740.7$-$2942 over the years 2003$-$2012