Kavli Affiliate: Renxin Xu
| First 5 Authors: Jie Lin, Chunqian Li, Weiyang Wang, Heng Xu, Jinchen Jiang
| Summary:
We report the discovery of a dark companion to 2MASS J15274848+3536572 with
an orbital period of 6.14 hours. Combining the radial velocity of LAMOST
observation and the modelling of the multi-band light curve, one has a mass
function of 0.135 Msun, an inclination of 43.94+0.33-0.21, and a mass ratio of
0.58+0.048-0.018, which demonstrate the binary nature of a dark companion with
mass of 1.01+-0.08Msun and a main-sequence K star of 0.59+-0.05 Msun. LAMOST
optical spectra at a range of orbital phase reveals extra peaked Halpha
emission that suggests the presence of an accretion disk. The dark companion
does not seem to be a white dwarf because the lack of any observed dwarf nova
outbursts contradicts with the disk instability model in long-term data
archive. Alternatively, we propose a scenario that the dark companion is a
neutron star, but we have not detected radio pulsation or single pulse from the
system with the FAST (Five hundred meter Aperture Spherical radio Telescope),
which hints a radio quiet compact object. If the dark companion is identified
as a neutron star, it will be nearest (118 pc) and lightest neutron star.
Furthermore, a kinematic analysis of the systems orbit in the galaxy may
suggest its supernova event is associated with the radionuclide 60Fe signal
observed from the deep-sea crusts. This radio-quiet and X-ray dim nearby
neutron star may resemble an XDINS (X-ray dim isolated neutron star), but in a
binary.
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