Letter to the Editor

Swift, RXTE, and INTEGRAL observation of Swift J1922.7-1716

¹ CEA Saclay, DSM/DAPNIA/Service d'Astrophysique (CNRS FRE 2591), 91191 Gif-sur-Yvette, France e-mail: mfalanga@cea.fr
² Unité mixte de recherche Astroparticule et Cosmologie, 11 place Berthelot, 75005 Paris, France
³ INAF - Osservatorio Astronomico di Brera, via Bianchi 46, 23807 Merate, Italy

Received: 19 April 2006
Accepted: 1 July 2006

Abstract

We report the results of analyzing Swift, RossiXTE, and INTEGRAL data of Swift J1922.7-1716, a likely transient X-ray source discovered by Swift/BAT. Both the fast variability measured by the RXTE/PCA and the combined Swift/XRT, RXTE/PCA, and INTEGRAL/ISGRI (0.5–100 keV) energy spectrum suggest that the system is a neutron-star low-mass X-ray binary or a black-hole candidate at low accretion levels. The non-simultaneous spectra are consistent with the same spectral shape and flux, suggesting little variability over the period July to October 2005, but the analysis of archival INTEGRAL data shows that the source was not detected in 2003–2004, suggesting a transient or strongly variable behavior.