Second outburst of the black hole candidate MAXI J1836-194 from SWIFT and INTEGRAL observations
Abstract
Details of the observations of a new (second) outburst of the X-ray transientMAXI J1836-194 discovered late in August 2011, a suspected black hole in a low-mass binary system, with the instruments of the SWIFT and INTEGRAL orbiting observatories are presented. The outburst was weaker than the first one; the source had a power-law spectrum in a wide X-ray (0.3-400 keV) energy range without any clear evidence for the presence of a soft (blackbody) component related to the emission from the outer accretion disk regions. This shows that the outburst was a "failed" one: the source did not pass through the sequence of spectral states characteristic of X-ray novae. The observed optical emission from the source whose variability was strongly correlated with its X-ray variability seems to have also been an extension of the power-law spectrum. Spectrum uniformity is, on the whole, unusual for other sources containing a black hole and raises the question about the nature of the emission from MAXI J1836-194 (disk or jet).
- Publication:
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Astronomy Letters
- Pub Date:
- June 2013
- DOI:
- 10.1134/S1063773713060054
- Bibcode:
- 2013AstL...39..367G
- Keywords:
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- X-ray sources;
- transients;
- black holes