IGR J18136-2739

Abstract

IGR J18136-2739 is a new transient INTEGRAL/IBIS source which has been caught in outburst during only a short period of time (26-29 August 2003). Motivated by this finding, we acquired observations with the X-ray telescope (XRT, 0.3-10 keV) on board Swift, in order to assess the nature of this source. At the border of the 90% IBIS error circle we detect for the first time in X-rays the dwarf nova V1830 Sgr and propose it as the likely counterpart to the IBIS source. The combined use of the spectral information afforded by XRT and IBIS indicates that the source spectrum is best fitted with either a simple power law with Γ ∼ 2.6 or a thermal bremsstrahlung with kT ∼ 17 keV; it also indicates the presence of variability in the source, as also highlighted by the occasional IBIS detection. V1830 Sgr is the second dwarf nova (DN) discovered by IBIS after SS Cyg. Show more