English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The accreting black-hole binary XTE J1752--223 was observed in a stable hardstate for 25 d by RXTE, yielding a 3--140 keV spectrum of unprecedentedstatistical quality. Its published model required a single Comptonizationspectrum reflecting from a disk close to the innermost stable circular orbit.We studied that model as well as a number of other single-Comptonization models(yielding similarly low inner radii), but found they violate a number of basicphysical constraints, e.g., their compactness is much above the maximum allowedby pair equilibrium. We also studied the contemporaneous 0.55--6 keV spectrumfrom the Swift/XRT and found it well fitted by an absorbed power law and a diskblackbody with the innermost temperature of 0.1 keV. The normalization of thedisk blackbody corresponds to an inner radius of $\gtrsim$20 gravitationalradii and its temperature, to irradiation of the truncated disk by a hot innerflow. We have also developed a Comptonization/reflection model including thedisk irradiation and intrinsic dissipation, but found that it does not yieldany satisfactory fits. On the other hand, we found that the $\leq$10 keV bandfrom RXTE is much better fitted by a reflection from a disk with the innerradius $\gtrsim$100 gravitational radii, which model then underpredicts thespectrum at $>$10 keV by $<$10%. We argue that the most plausible explanationof the above results is inhomogeneity of the source, with the local spectrahardening with the decreasing radius. Our results support the presence of acomplex Comptonization region and a large disk truncation radius in thissource.

Does the disk in the hard state of XTE J1752-223 extend to the innermost stable circular orbit?