Broad-band X-ray spectral evolution of GX 339-4 during a state transition

We report on X-ray and soft gamma-ray observations of the black hole candidate GX 339-4 during its 2007 outburst, performed with the RXTE and INTEGRAL satellites. The hardness-intensity diagram of all RXTE/PCA data combined shows a q-shaped track similar to that observed in previous outbursts. The evolution in the diagram suggested that a transition from hard-to soft-intermediate state occurred, simultaneously with INTEGRAL observations performed in March. The transition is confirmed by the timing analysis presented in this work, which reveals that a weak type-A quasi-periodic oscillation (QPO) replaces a strong type-C QPO. At the same time, spectral analysis shows that the flux of the high-energy component shows a significant decrease in its flux. However, we observe a delay (roughly one day) between variations of the spectral parameters of the high-energy component and changes in the flux and timing properties. The changes in the high-energy component can be explained either in terms of the high-energy cut-off or in terms of variations in the reflection component. We compare our results with those from a similar transition during the 2004 outburst of GX 339-4.

[1]  T. Belloni.  The jet paradigm : from microquasars to quasars , 2010 .

[2]  P. Ubertini,et al.  Spectral variability of GX 339−4 in a hard-to-soft state transition , 2008, 0807.1018.

[3]  Aya Kubota,et al.  Modelling the behaviour of accretion flows in X-ray binaries , 2007, 0708.0148.

[4]  H. Schatz,et al.  X-ray binaries , 2006, astro-ph/0607624.

[5]  W. Lewin,et al.  Compact stellar X-ray sources , 2006 .

[6]  J. McClintock,et al.  Compact Stellar X-Ray Sources: Black hole binaries , 2006 .

[7]  W. Lewin,et al.  INTEGRAL/RXTE high-energy observation of a state transition of GX 339–4 , 2006, astro-ph/0601031.

[8]  T. Belloni.  Black-hole transients: From QPOs to relativistic jets , 2005, astro-ph/0507556.

[9]  Usa,et al.  The evolution of the timing properties of the black-hole transient GX 339-4 during its 2002/2003 outburst , 2005, astro-ph/0504577.

[10]  L. Stella,et al.  The ABC of Low-Frequency Quasi-periodic Oscillations in Black Hole Candidates: Analogies with Z Sources , 2005, astro-ph/0504318.

[11]  Charles D. Bailyn,et al.  Multiwavelength Observations of the 2002 Outburst of GX 339–4: Two Patterns of X-Ray-Optical/Near-Infrared Behavior , 2005, astro-ph/0501349.

[12]  L. Natalucci,et al.  1E 1740.7-2942: Temporal and spectral evolution from INTEGRAL and RXTE observations , 2004, astro-ph/0411544.

[13]  T. Belloni,et al.  The Evolution of Black Hole States , 2004, astro-ph/0412597.

[14]  T. Belloni,et al.  A Unified Model for Black Hole X-Ray Binary Jets? , 2004, astro-ph/0506469.

[15]  M. Gierliński,et al.  Radiative Processes, Spectral States and Variability of Black-Hole Binaries(Session 4 : Theoretical/Numerial Approaches to the Accretion Physics) , 2004, astro-ph/0403683.

[16]  Shunji Kitamoto,et al.  GX 339—4: the distance, state transitions, hysteresis and spectral correlations , 2004, astro-ph/0402380.

[17]  T. Maccarone,et al.  A transient large-scale relativistic radio jet from GX 339−4 , 2003, astro-ph/0311452.

[18]  B. Ramsey,et al.  IBIS: The Imager on-board INTEGRAL , 2003 .

[19]  M. Rouger,et al.  ISGRI: The INTEGRAL soft gamma-ray imager , 2003, astro-ph/0310362.

[20]  Jon M. Miller,et al.  A transient variable 6 Hz QPO from GX 339-4 , 2003, astro-ph/0309437.

[21]  T. Maccarone,et al.  Hysteresis in the light curves of soft X-ray transients , 2002, astro-ph/0209116.

[22]  J. H. Swank,et al.  Two Different Long-Term Behaviors in Black Hole Candidates: Evidence for Two Accretion Flows? , 2001, astro-ph/0103304.

[23]  Utrecht,et al.  X-ray/optical bursts from GS 1826–24 , 1999, astro-ph/9909488.

[24]  M. Klis,et al.  The EXOSAT Data on GX 339–4: Further Evidence for an “Intermediate” State , 1996, astro-ph/9611015.

[25]  Edward H. Morgan,et al.  Dead-Time Modifications to Fast Fourier Transform Power Spectra , 1995 .

[26]  A. Zdziarski,et al.  Angle-dependent Compton reflection of X-rays and gamma-rays , 1995 .

[27]  Kazuhiro Kimura,et al.  X-ray variability of GX 339 - 4 in its very high state , 1991 .

[28]  K. Makishima,et al.  Short-term X-ray variability of GX 339 - 4 , 1984 .

[29]  Martin C. Weisskopf,et al.  On searches for pulsed emission with application to four globular cluster X-ray sources - NGC 1851, 6441, 6624, and 6712 , 1983 .

[30]  H. Schnopper,et al.  Observations of the highly variable X-ray source GX 339-4. , 1973 .