X-ray Dip Monitoring of XB 1916-053

Abstract

We report on the long term monitoring of X-ray dips from the ultracompact low-mass X-ray binary (LMXB) XB 1916-053. Roughly one-month interval observations were carried out with the Rossi X-ray Timing Explorer (RXTE) during 1996, during which the source varied between dim, hard states and more luminous, soft states. The dip spectra and dip lightcurves were compared against both the broadband luminosity and the derived mass accretion rate Mdot. The dips spectra could be fitted by an absorbed blackbody plus cut-off power law non-dip spectral model, with additional absorption ranging from 0 to >100 x 10^22 cm^-2. The amount of additional blackbody absorption was found to vary with the source luminosity. Our results are consistent with an obscuration of the inner disk region by a partially ionized outer disk. The size of the corona, derived from the dip ingress times, was found to be ~10^9 cm. The corona size did not correlate with the coronal temperature, but seemed to increase when \Mdot also increased. We discuss our findings in the context of an evaporated accretion disk corona model and an ADAF-type model.

arXiv commentAccepted for publication in ApJ, 15 pages

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Cited by in corpus (5)

• Measurements of accretion disc corona size in LMXB: consequences for Comptonization and LMXB models
• X-ray Spectroscopy of the High Mass X-ray Binary Pulsar Centaurus X-3 over its Binary Orbit
• SPH simulations of irradiation-driven warped accretion discs and the long periods in X-ray binaries
• Chandra Observation of the Persistent Emission from the Dipping Source XB 1916-053
• A study of the low-mass X-ray binary dip sources XB 1916-053, XB 1323-619, X 1624-490 and 4U 1746-371 observed with INTEGRAL