A Propeller-effect Interpretation of MAXI/GSC Light Curves of 4U 1608-52 and Aql X-1 and Application to XTE J1701-462
Abstract
We present the luminosity dwell-time distributions during the hard states of two low-mass X-ray binaries containing a neutron star (NS), 4U 1608-52 and Aql X-1, observed with MAXI/GSC. The luminosity distributions show a steep cutoff on the low-luminosity side at ~1.0 × 1036 erg s-1 in both sources. The cutoff implies a rapid luminosity decrease in their outburst decay phases and this decrease can be interpreted as being due to the propeller effect. We estimate the surface magnetic field of 4U 1608-52 to be (0.5-1.6) × 108 G and Aql X-1 to be (0.6-1.9) × 108 G from the cutoff luminosity and apply the same propeller mechanism to the similar rapid luminosity decrease observed in the transient Z source, XTE J1701-462, with RXTE/ASM. Assuming that the spin period of the NS is on the order of milliseconds, the observed cutoff luminosity implies a surface magnetic field on the order of 109 G.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- August 2013
- DOI:
- 10.1088/0004-637X/773/2/117
- arXiv:
- arXiv:1306.3545
- Bibcode:
- 2013ApJ...773..117A
- Keywords:
-
- stars: neutron;
- X-rays: binaries;
- X-rays: individual: Aql X-1 4U 1608-52 XTE J1701-462;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 14 pages, 5 figures