The nature of the X-ray transient SAX J1711.6-3808

in't Zand, J. J. M.; Markwardt, C. B.; Bazzano, A.; Cocchi, M.; Cornelisse, R.; Heise, J.; Kuulkers, E.; Natalucci, L.; Santos-Lleo, M.; Swank, J.; Ubertini, P.
Referencia bibliográfica

Astronomy and Astrophysics, v.390, p.597-609 (2002)

Fecha de publicación:
8
2002
Número de autores
11
Número de autores del IAC
0
Número de citas
21
Número de citas referidas
18
Descripción
SAX J1711.6-3808 is an X-ray transient in the Galactic bulge that was active from January through May of 2001 and whose maximum 1-200 keV luminosity was measured to be 5x 10-9 erg cm-2 s-1 which is less than ~ 25% of the Eddington limit, if placed at a distance equal to that of the galactic center. We study the X-ray data that were taken of this moderately bright transient with instruments on BeppoSAX and RXTE. The spectrum shows two interesting features on top of a Comptonized continuum commonly observed in low-state X-ray binaries: a broad emission feature peaking at 7 keV and extending from 4 to 9 keV, and a soft excess with a color temperature below 1 keV which reveals itself only during one week of data. High time-resolution analysis of 412 ksec worth of data fails to show bursts, coherent or high-frequency quasi-periodic oscillations. Given the dynamic range of the flux measurements, this would be unusual if a neutron star were present. SAX J1711.6-3808 appears likely to contain a black hole. No quiescent optical counterpart could be identified in archival data within the 5arcsec-radius XMM error circle, but the limits are not very constraining because of heavy extinction (A_{ V}=16).