A Search for Technosignatures Around 11,680 Stars with the Green Bank Telescope at 1.15–1.73 GHz

• Published in: The Astronomical journal Vol. 166; no. 5; pp. 206 - 220
• Main Authors: Margot, Jean-Luc, Li, Megan G., Pinchuk, Pavlo, Myhrvold, Nathan, Lesyna, Larry, Alcantara, Lea E., Andrakin, Megan T., Arunseangroj, Jeth, Baclet, Damien S., Belk, Madison H., Bhadha, Zerxes R., Brandis, Nicholas W., Carey, Robert E., Cassar, Harrison P., Chava, Sai S., Chen, Calvin, Chen, James, Cheng, Kellen T., Cimbri, Alessia, Cloutier, Benjamin, Combitsis, Jordan A., Couvrette, Kelly L., Coy, Brandon P., Davis, Kyle W., Delcayre, Antoine F., Du, Michelle R., Feil, Sarah E., Fu, Danning, Gilmore, Travis J., Grahill-Bland, Emery, Iglesias, Laura M., Juneau, Zoe, Karapetian, Anthony G., Karfakis, George, Lambert, Christopher T., Lazbin, Eric A., Li, Jian H., Li, Zhuofu (Chester), Liskij, Nicholas M., Lopilato, Anthony V., Lu, Darren J., Ma, Detao, Mathur, Vedant, Minasyan, Mary H., Muller, Maxwell K., Nasielski, Mark T., Nguyen, Janice T., Nicholson, Lorraine M., Niemoeller, Samantha, Ohri, Divij, Padhye, Atharva U., Penmetcha, Supreethi V., Prakash, Yugantar, Qi, Xinyi (Cindy), Rindt, Liam, Sahu, Vedant, Scally, Joshua A., Scott, Zefyr, Seddon, Trevor J., Shohet, Lara-Lynn V., Sinha, Anchal, Sinigiani, Anthony E., Song, Jiuxu, Stice, Spencer M., Tabucol, Nadine M., Uplisashvili, Andria, Vanga, Krishna, Vazquez, Amaury G., Vetushko, George, Villa, Valeria, Vincent, Maria, Waasdorp, Ian J., Wagaman, Ian B., Wang, Amanda, Wight, Jade C., Wong, Ella, Yamaguchi, Natsuko, Zhang, Zijin, Zhao, Junyang, Lynch, Ryan S.
• Format: Journal Article
• Language: English
• Published: Madison The American Astronomical Society 01.11.2023; IOP Publishing
• Subjects: Anthropogenic factors; Astrobiology; ASTRONOMY AND ASTROPHYSICS; Confidence intervals; Efficiency; Exoplanets; Figure of merit; Frequency ranges; L-band receivers; Milky Way Galaxy; Narrowband; Planetary systems; Radio astronomy; Radio emission; Radio frequency interference; Radio signals; Receivers & amplifiers; Recovery; Search for extraterrestrial intelligence; Searching; Signal injection; Stars; Technosignatures; Telescopes; Transmitters
• ISSN: 0004-6256; 1538-3881
• DOI: 10.3847/1538-3881/acfda4

Abstract We conducted a search for narrowband radio signals over four observing sessions in 2020–2023 with the L -band receiver (1.15–1.73 GHz) of the 100 m diameter Green Bank Telescope. We pointed the telescope in the directions of 62 TESS Objects of Interest, capturing radio emissions from a total of ∼11,680 stars and planetary systems in the ∼9′ beam of the telescope. All detections were either automatically rejected or visually inspected and confirmed to be of anthropogenic nature. We also quantified the end-to-end efficiency of radio SETI pipelines with a signal injection and recovery analysis. The UCLA SETI pipeline recovers 94.0% of the injected signals over the usable frequency range of the receiver and 98.7% of the injections when regions of dense radio frequency interference are excluded. In another pipeline that uses incoherent sums of 51 consecutive spectra, the recovery rate is ∼15 times smaller at ∼6%. The pipeline efficiency affects calculations of transmitter prevalence and SETI search volume. Accordingly, we developed an improved Drake figure of merit and a formalism to place upper limits on transmitter prevalence that take the pipeline efficiency and transmitter duty cycle into account. Based on our observations, we can state at the 95% confidence level that fewer than 6.6% of stars within 100 pc host a transmitter that is continuously transmitting a narrowband signal with an equivalent isotropic radiated power (EIRP) > 10 13 W. For stars within 20,000 ly, the fraction of stars with detectable transmitters (EIRP > 5 × 10 16 W) is at most 3 × 10 −4 . Finally, we showed that the UCLA SETI pipeline natively detects the signals detected with AI techniques by Ma et al.