First Results from the Swarms Survey. SDSS 1257+5428: A Nearby, Massive White Dwarf Binary with a Likely Neutron Star or Black Hole Companion

摘要

We present the first results from SWARMS (Sloan White dwArf Radial velocitydata Mining Survey), an ongoing project to identify compact white dwarf (WD)binaries in the spectroscopic catalog of the Sloan Digital Sky Survey. Thefirst object identified by SWARMS, SDSS 1257+5428, is a single-linedspectroscopic binary in a circular orbit with a period of 4.56 hr and asemiamplitude of 322.7+-6.3 km/s. From the spectrum and photometry, we estimatea WD mass of 0.92(+0.28,-0.32) Msun. Together with the orbital parameters ofthe binary, this implies that the unseen companion must be more massive than1.62(+0.20,-0.25) Msun, and is in all likelihood either a neutron star or ablack hole. At an estimated distance of 48(+10,-19) pc, this would be theclosest known stellar remnant of a supernova explosion.