Searching for BH/NS Candidates in Ellipsoidal Variables

Using the Double Spectrograph (DBSP) instrument on the 200-inch telescope at Palomar Observatory, I performed multi-epoch spectroscopic follow-up of a sample of ellipsoidal variables selected from Gaia DR3 as candidates for hosting quiescent black holes (BHs) or neutron stars (NSs). Under the assumption that all variability is due to tidal deformation, the optical light curves of these objects suggested the presence of massive unseen companions. However, the measured radial velocity semi-amplitudes were unexpectedly small, making it unlikely that any of these systems contained a BH or NS. Using PHysics Of Eclipsing BinariEs (PHOEBE) modeling, I showed that extreme mass-ratio contact binaries with starspots provided a reasonable alternative explanation for the observed photometric variability, though single-star scenarios can not be ruled out. I am currently pursuing a more thorough characterization of the original Gaia DR3 sample through SDSS-V, an all-sky survey capable of multi-object, multi-epoch spectroscopy.

Read more about this research project in the associated publication here.