Sensitive Multibeam Targeted SETI Observations toward 33 Exoplanet Systems with FAST

Abstract

As a major approach to looking for life beyond the Earth, the search for extraterrestrial intelligence (SETI) is committed to searching for technosignatures such as engineered radio signals that are indicative of technologically capable life. In this paper, we report a targeted SETI campaign employing an observation strategy named multibeam coincidence matching at the Five-hundred-meter Aperture Spherical radio Telescope toward 33 known exoplanet systems, searching for ETI narrowband drifting signals across 1.05–1.45 GHz in two orthogonal linear polarization directions separately. A signal at 1140.604 MHz detected from the observation toward Kepler-438 originally piqued our interest because its features are roughly consistent with assumed ETI technosignatures. However, evidences such as its polarization characteristics are able to eliminate the possibility of an extraterrestrial origin. Our observations achieve an unprecedented sensitivity because the minimum equivalent isotropic radiated power we are able to detect reaches 1.48 × 109 W.

Multibeam Blind Search of Targeted SETI Observations toward 33 Exoplanet Systems with FAST

“…Referring to the data up to October 2020 from the NASA Exoplanet Archive 1 and considering the observable sky of FAST, we observe 33 exoplanet systems from April 19, 2021 to September 21, 2021. More importantly, the targets are selected considering habitability, celestial position, size, and distance, 29 out of 33 exoplanet systems were detected to contain planets in their habitable zones, and 5 of them are within the earth transit zone (Tao et al 2022).…”

“…The basic principle of the on-off strategy is that an ETI signal from the target can only be detected in the onobservation, while RFI can be detected in both on and off observations (Enriquez et al 2017). Based on the FAST 19-beam receiver, Tao et al (2022) designed the MBCM strategy for targeted SETI observations. The MBCM strategy states that multiple beams are observed and compared simultaneously to identify the origin of a signal.…”

“…In recent years, targeted SETI observations are increasingly being conducted toward exoplanets and some nearby stars by many radio telescopes in various countries. For example: studies from the Breakthrough Listen initiative (BL) using the Green Bank Telescope (GBT) and the Parkes Telescope (Parkes) (Enriquez et al 2017;Price et al 2020;Sheikh et al 2020;Traas et al 2021;Smith et al 2021;Gajjar et al 2021); observations toward planetary systems by the Allen Telescope Array (ATA) (Harp et al 2016(Harp et al , 2018(Harp et al , 2020; many SETI surveys using the Murchison Widefield Array (MWA) (Tingay et al 2016(Tingay et al , 2018Tremblay & Tingay 2020); observations focused on Sun-like Stars and planetary systems in the Kepler field with GBT (Pinchuk et al 2019;Margot et al 2021); a Very Large Array (VLA) search for technosignatures from M31 and M33 (Gray & Mooley 2017); and the targeted observations of 33 exoplanets by China's Five-hundred-meter Aperture Spherical radio Telescope (FAST) (Tao et al 2022). However, there is no conclusive evidence of ETI technosignatures from any research so far.…”

“…In 2019, the first SETI sky survey of FAST was conducted by commensal observations (Zhang et al 2020). In 2021, the first targeted SETI observations were also conducted by FAST toward exoplanet systems (Tao et al 2022). Since the 19-beam receiver can simultaneously receive signals from different sky regions, the targeted SETI observations of FAST can identify RFI without using the on-off strategy.…”

Drift Rates of Narrowband Signals in Long-term SETI Observations for Exoplanets

“…The Five-hundred-meter Aperture Spherical radio Telescope (FAST) is the largest single-aperture radio telescope in the world (Li & Pan 2016), covering 57% of celestial sphere. As the most sensitive radio telescope in the world (Jiang et al 2020;Wang et al 2021a), FAST has carried out its first SETI observation by drift-scan survey (Zhang et al 2020) and the first targeted SETI observation (Tao et al 2022). Since FAST has its unique advantages of large sky coverage and high sensitivity, we use FAST as an example of receivers on Earth in the following calculations.…”