Bibcode
Casares, J.; Rebolo, R.; González Hernández, J. I.
Bibliographical reference
Monthly Notices of the Royal Astronomical Society: Letters, Volume 438, Issue 1, p.L21-L25
Advertised on:
2
2014
Citations
52
Refereed citations
48
Description
We present new 10.4 m-GTC/OSIRIS spectroscopic observations of the black
hole X-ray binary XTE J1118+480 that confirm the orbital period decay at
dot{P}=-1.90± 0.57 ms yr-1. This corresponds to a
period change of -0.88 ± 0.27 μs per orbital cycle. We have
also collected observations of the black hole X-ray binary A0620-00 to
derive an orbital period derivative of dot{P}=-0.60± 0.08 ms
yr-1 (-0.53 ± 0.07 μs/cycle). Angular momentum
losses due to gravitational radiation are unable to explain these large
orbital decays in these two short-period black hole binaries. The
orbital period decay measured in A0620-00 is very marginally consistent
with the predictions of conventional models including magnetic braking,
although significant mass-loss (dot{M}_BH / dot{M}_2 ≤ 20 per cent)
from the system is required. The fast spiral-in of the star in XTE
J1118+480, however, does not fit any standard model and may be driven by
magnetic braking under extremely high magnetic fields and/or may require
an unknown process or non-standard theories of gravity. This result may
suggest an evolutionary sequence in which the orbital period decay
begins to speed up as the orbital period decreases. This scenario may
have an impact on the evolution and lifetime of black hole X-ray
binaries.
Related projects
Black holes, neutron stars, white dwarfs and their local environment
Accreting black-holes and neutron stars in X-ray binaries provide an ideal laboratory for exploring the physics of compact objects, yielding not only confirmation of the existence of stellar mass black holes via dynamical mass measurements, but also the best opportunity for probing high-gravity environments and the physics of accretion; the most
Montserrat
Armas Padilla