Old Isolated Accreting Neutron Stars: Contribution to the Soft X-Ray Background in the 0.5--2 keV Band
The issue of the observability of old isolated neutron stars (ONSs) accreting from the interstellar gas is reconsidered using the spectra presented by Zampieri et al. In particular, we focus our attention on the overall soft X-ray emission of ONSs, which may provide a substantial contribution to the X-ray background in the 0.5-2 keV band. It is found that if accretion is channeled into polar caps by a magnetic field of ∼109 G, up to ∼12%-25% of the unresolved soft excess observed at high latitudes in the X-ray background can be explained in terms of emission from accreting isolated ONSs. However, this would imply the detection with ROSAT of ∼10 sources deg-2 above a threshold of ∼10-14 ergs cm-2 s-1. A brief reconsideration of the observability of isolated ONSs as individual X-ray sources is also presented.
The Astrophysical Journal
- Pub Date:
- October 1995
- COSMOLOGY: DIFFUSE RADIATION;
- STARS: NEUTRON;
- X-RAYS: GENERAL;
- X-RAYS: STARS;
- 23 pages plus 5 tables, included at the end as separate TeX files (2 postscript figures available upon request), PlainTeX, submitted to ApJ.