Broad-band spectral changes of the microquasars Cygnus X-1 and SWIFT J1753.5-0127

Marion Cadolle Bel (1, 2) , Marc Ribo (3) , Jerome Rodriguez (1) , Sylvain Chaty (1) , Stephane Corbel (1) , Andrea Goldwurm (1)

1 DAPNIA - Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée
2 ESAC - European Space Astronomy Centre
3 UB - Universitat de Barcelona

We report high-energy results obtained with INTEGRAL and Rossi-XTE on two microquasars: the persistent high-mass system Cygnus X-1 and the transient low-mass binary SWIFT J1753.5-0127. INTEGRAL observed Cygnus X-1 from 2002 to 2004: the spectral (5-1000 keV) properties of the source, seen at least in three distinct spectral states, show disc and corona changes. In 2003 June, a high-energy tail at several hundred keV in excess of the thermal Comptonization model was observed, suggesting the presence of an additional non-thermal component. At that time, we detected an unusual correlation between radio data and high-energy hardness. We also report and compare the results obtained with simultaneous observations of the transient source SWIFT J1753.5-0127 performed with Rossi-XTE, INTEGRAL, VLA, REM and NTT on 2005 August 10-12 near its hard X-ray outburst. Broad-band spectra and fast time-variability properties are derived on this source (probably located in the galactic halo) together with radio, IR and optical data. We build a spectral energy distribution of the source and derive interesting multiwavelength constraints. Significantly detected up to 600 keV in a typical Low/Hard State, the transient does not seem to follow the usual radio/X-ray correlation.

Domaines: Cosmologie et astrophysique extra-galactique [astro-ph.CO]

Marion Cadolle Bel, Marc Ribo, Jerome Rodriguez, Sylvain Chaty, Stephane Corbel, et al.. Broad-band spectral changes of the microquasars Cygnus X-1 and SWIFT J1753.5-0127. Microquasars and Beyond, 18-22 September 2006, Sep 2006, Como, Italy. ⟨hal-00112112⟩