Cyclotron Resonance Energies at a Low X-Ray Luminosity: A0535+262 Observed with Suzaku
Abstract
The binary X-ray pulsar A0535+262 was observed with the Suzaku X-ray observatory on 2005 September 14 for a net exposure of 22 ks. The source was in the declining phase of a minor outburst, exhibiting 3-50 keV luminosity of ~3.7×1035 ergs s-1 at an assumed distance of 2 kpc. In spite of the very low source intensity (about 30 mcrab at 20 keV), its electron cyclotron resonance was detected clearly with the Suzaku Hard X-Ray Detector, in absorption at about 45 keV. The resonance energy is found to be essentially the same as that measured when the source is almost 2 orders of magnitude more luminous. These results are compared with the luminosity-dependent changes in the cyclotron resonance energy, observed from 4U 0115+63 and X0331+53.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 2006
- DOI:
- 10.1086/508018
- arXiv:
- arXiv:astro-ph/0607659
- Bibcode:
- 2006ApJ...648L.139T
- Keywords:
-
- Magnetic Fields;
- Stars: Pulsars: Individual: Alphanumeric: A0535+26;
- Stars: Neutron;
- X-Rays: Binaries;
- Astrophysics
- E-Print:
- 12 pages, 4 figures, accepted to ApJL, high resolution version is available from http://cosmic.riken.jp/terada/01work/paper/a0535_suzaku2006.pdf