The Fast Spiral-in of the Companion Star to the Black Hole XTE J1118+480
Abstract
We report the detection of an orbital period decay of \dot{P}=-1.83+/- 0.66 ms yr-1 in the black hole X-ray binary XTE J1118+480. This corresponds to a period change of -0.85 ± 0.30 μs per orbital cycle, which is ~150 times larger than expected from the emission of gravitational waves. These observations cannot be reproduced by conventional models of magnetic braking even when including significant mass loss from the system. The spiral-in of the star is either driven by magnetic braking under extremely high magnetic fields in the secondary star or by a currently unknown process, which will have an impact on the evolution and lifetime of black hole X-ray binaries.
Based on observations made with the Gran Telescopio Canarias (GTC), installed in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, in the island of La Palma.- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 2012
- DOI:
- 10.1088/2041-8205/744/2/L25
- arXiv:
- arXiv:1112.1839
- Bibcode:
- 2012ApJ...744L..25G
- Keywords:
-
- black hole physics;
- gravitation;
- stars: individual: XTE J1118+480;
- stars: magnetic field;
- X-rays: binaries;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- accepted for publication in ApJ letters