Measuring a Truncated Disk in Aquila X-1
Abstract
We present NuSTAR and Swift observations of the neutron star Aquila X-1 during the peak of its 2014 July outburst. The spectrum is soft with strong evidence for a broad Fe Kα line. Modeled with a relativistically broadened reflection model, we find that the inner disk is truncated with an inner radius of 15+/- 3{R}G. The disk is likely truncated by either the boundary layer and/or a magnetic field. Associating the truncated inner disk with pressure from a magnetic field gives an upper limit of B\lt 5+/- 2× {10}8 G. Although the radius is truncated far from the stellar surface, material is still reaching the neutron star surface as evidenced by the X-ray burst present in the NuSTAR observation.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 2016
- DOI:
- 10.3847/2041-8205/819/2/L29
- arXiv:
- arXiv:1602.07664
- Bibcode:
- 2016ApJ...819L..29K
- Keywords:
-
- accretion;
- accretion disks;
- magnetic fields;
- stars: neutron;
- X-rays: binaries;
- X-rays: bursts;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- ApJL Accepted, 8 pages, 4 figures