The 2009 outburst of H 1743-322 as observed by RXTE

¹ Laboratory for Particle Astrophysics, Institute of High Energy Physics, 100049 Beijing, PR China
e-mail: chenyp@mail.ihep.ac.cn
² ICREA & Institut de Ciències de l’Espai (IEEC-CSIC), Campus UAB, Facultat de Ciències, Torre C5-parell, 2a planta, 08193 Barcelona, Spain
³ Theoretical Physics Center for Science Facilities (TPCSF), CAS, 100049 Beijing, PR China
⁴ Center for Astrophysics,Tsinghua University, Beijing 100084, PR China

Received: 8 January 2010
Accepted: 16 August 2010

Abstract

Context. Six outbursts have been observed by RXTE from the source since 2003. Following “a failed outburst” with a missing high/soft state in 2008, the most recent one occurred in 2009, exhibiting all spectral transitions.

Aims. An outburst was observed by RXTE from the black hole candidate H 1743-322 in 2009. We investigate this particular outburst in the context of the source outburst history.

Methods. We analyze the RXTE observations of the 2009 outburst of H 1743-322, as well as the observations of the previous five outbursts for comparison. All available RXTE observations taken since 2003 sum up to a total exposure of  ~1200 ks.

Results. The hardness-intensity diagram (HID) shows a complete counter-clockwise q-track for the 2009 outburst. It leaves the low/hard state but does not reach the leftmost edge of the overall HID. Near maximum, the X-ray spectra show a power law with photon index  < 2.4; the peak luminosity during the whole outburst reached only 20% of the Eddington luminosity. The highest disk fractional luminosity is about 0.75 for the 2009 outburst, which is close to the lower limit observed from the black hole XRB sample in their state transitions from the intermediate to the high/soft state. While the lowest hardness (6–19 keV/3–6 keV) values in the HID is about 0.3–0.4 for the 2009 outburst, the timing analysis shows that a transition to the high soft state occurred. During the low/hard state of the 2009 outburst, the inner radius of the accretion disk is found to be closer to the central black hole and anti-correlated with the disk temperature implying reprocessing of the hot corona on the disk’s soft X-rays. In the luminosity diagram of the corona versus the disk, the tracks of the outbursts in 2003 and 2009 cross the line which represents a roughly equal contribution to the emission from the thermal and the non-thermal components; the track of the 2008 outburst has its turn-over falling on this line. This may indicate an emission balance between the corona and the disk that prevents the state transition from going further than the low/hard state.