A Model-Independent Radio Telescope Dark Matter Search*

While significant attention has been paid to a few specific dark matter candidates such as the WIMP and axion, in fact the nature and mass of dark matter is poorly constrained, and thus a broad observational strategy may prove helpful toward its ultimate identification. We have developed and carried out a novel search technique for ultralight dark matter over a narrow range in L-band, utilizing the recent Breakthrough Listen public data release of three years of observation with the Green Bank Telescope. The search concept depends only on the assumption of decay or annihilation of virialized dark matter to a quasi-monochromatic radio line, and additionally that the frequency and intensity of the line be consistent with most general properties expected of the phase space of our Milky Way halo. Specifically, the search selects for a line which exhibits a Doppler shift with position according to the solar motion through a static galactic halo, and similarly varies in intensity with position with respect to the galactic center. Over the frequency range 1.73-1.83 GHz, radiative annihilation of dark matter is excluded above〈σv〉 =  1.2 x 10^-47 cm³ s^-1, and for decay above  λ  =  4.1 x 10^-35 s^-1. The analysis of the full L-, S-, C- and X-band dataset by this method (25,000 spectra, 1.1-11.6 GHz) is currently underway.