Narrowband Signal Searches Towards the Galactic Plane and Center

Abstract:

Over the last decade, discoveries of Earth-type exoplanets have extended the possibility of other life-bearing worlds. However, the question of the existence of intelligent life might remain elusive unless a dedicated attempt is made to extensively Search for Extraterrestrial Intelligence (SETI). The Breakthrough Listen (BL) program is a 10-year effort to conduct the most sensitive, comprehensive, and intensive search for advanced intelligent life on other worlds ever performed. Two of the primary targets of the BL program are the Galactic Center (GC) and a comprehensive blind survey of the entire Galactic Plane (GP) to search for artificial narrowband transmitters from ETIs. The line of sight toward the GC offers the largest integrated galactic star count of any direction in the sky, is a widely cited possible location for a beacon built by an advanced intelligence, and is the most energetic region in the Milky Way. Likewise, the GP is an ideal direction to search for such signals due to the increased likelihood that transmitters would emit toward this region as opposed to random directions. Here, I discuss our observation and narrowband search strategy, as well as results, for the Green Bank Telescope (GBT) (4-8 GHz) and Parkes Telescope (0.7-4 GHz) from our GC Survey so far. I also discuss an extension of these strategies for our GP Parkes 21cm Multibeam Receiver (1.2-1.55 GHz) Survey, which covers roughly 3000 square degrees during 1200 hours, were we have extended the multibeam coincidence rejection technique used for detecting Fast Radio Bursts to scrutinize narrowband signals detected across 13-beams. This allows us to discriminate terrestrial interferences from truly sky localized signals to help us reject large fractions of false positives. I will review our strategy and preliminary search results, as well as its applications going forward as we look towards expanding our search with other multibeam telescopes.