skip to main content


Title: Extended X-Ray Monitoring of Gravitational Lenses with Chandra and Joint Constraints on X-Ray Emission Regions
Award ID(s):
1614018
NSF-PAR ID:
10273537
Author(s) / Creator(s):
; ; ; ; ; ; ;
Date Published:
Journal Name:
The Astrophysical Journal
Volume:
836
Issue:
2
ISSN:
1538-4357
Page Range / eLocation ID:
206
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. We report on a comprehensive analysis of simultaneous X-ray polarimetric and spectral data of the bright atoll source GX 9+9 with the Imaging X-ray Polarimetry Explorer (IXPE) and NuSTAR . The source is significantly polarized in the 4–8 keV band, with a degree of 2.2%  ±  0.5% (uncertainty at the 68% confidence level). The NuSTAR broad-band spectrum clearly shows an iron line, and is well described by a model including thermal disc emission, a Comptonized component, and reflection. From a spectro-polarimetric fit, we obtain an upper limit to the polarization degree of the disc of 4% (at the 99% confidence level), while the contribution of Comptonized and reflected radiation cannot be conclusively separated. However, the polarization is consistent with resulting from a combination of Comptonization in a boundary or spreading layer, plus reflection off the disc, which significantly contributes in any realistic scenario. 
    more » « less
  2. null (Ed.)