Astronomy and Astrophysics, volume 394, 553-560 (2002/11-1)
Broad-band X-ray measurements of the black hole candidate XTE J1908+094.
IN'T ZAND J.J.M., MILLER J.M., OOSTERBROEK T. and PARMAR A.N.
Abstract (from CDS):
XTE J1908+094 is an X-ray transient that went into outburst in February 2002. After two months it reached a 2-250keV peak flux of 1 to 2x10–8erg/cm2/s. Circumstantial evidence points to an accreting galactic black hole as the origin of the X-radiation: pulsations nor thermonuclear flashes were detected that would identify a neutron star and the spectrum was unusually hard for a neutron star at the outburst onset. We report on BeppoSAX and RXTE All Sky Monitor observations of the broad-band spectrum of XTE J1908+094. The spectrum is consistent with a model consisting of a Comptonization component by a ∼40keV plasma, a multicolor accretion disk blackbody component with a temperature just below 1keV and a broad emission line at about 6keV. The spectrum is heavily absorbed by cold interstellar matter with an equivalent hydrogen column density of 2.5x1022cm–2, which makes it difficult to study the black body component in detail. The black body component exhibits strong evolution about 6 weeks into the outburst. Two weeks later this is followed by a swift decay of the power law component. The broadness of the 6keV feature may be due to relativistic broadening or Compton scattering of a narrow Fe-K line.