A 1.1-1.9 GHz SETI SURVEY OF THEKEPLERFIELD. I. A SEARCH FOR NARROW-BAND EMISSION FROM SELECT TARGETS

Abstract

We present a targeted search for narrow-band (< 5 Hz) drifting sinusoidal radio emission from 86 stars in the Kepler field hosting confirmed or candidate exoplanets. Radio emission less than 5 Hz in spectral extent is currently known to only arise from artificial sources. The stars searched were chosen based on the properties of their putative exoplanets, including stars hosting candidates with 380 K > T eq > 230 K, stars with 5 or more detected candidates or stars with a super-Earth (R p < 3 R ⊕ ) in a > 50 day orbit. Baseband voltage data across the entire band between 1.1 and 1.9 GHz were recorded at the Robert C. Byrd Green Bank Telescope between Feb-Apr 2011 and subsequently searched offline. No signals of extraterrestrial origin were found. We estimate that fewer than ∼1% of transiting exoplanet systems host technological civilizations that are radio loud in narrow-band emission between 1−2 GHz at an equivalent isotropically radiated power (EIRP) of ∼ 1.5 × 10 21 erg s −1 , approximately eight times the peak EIRP of the Arecibo Planetary Radar, and we limit the the number of 1−2 GHz narrow-band-radio-loud Kardashev type II civilizations in the Milky Way to be < 10 −6 M −1 . Here we describe our observations, data reduction procedures and results.

The Breakthrough Listen Search for Intelligent Life: 1.1–1.9 GHz Observations of 692 Nearby Stars

“…This type of signal is of particular interest in traditional SETI projects because it is too narrow to arise naturally from known natural astrophysical sources, and represents a power-efficient method of transmitting a beacon signal out to great distances. Given the relatively short distances to our targets, we are able to neglect the various interstellar distortions (Cordes et al 1997;Siemion et al 2013, e.g., scintillation in time and frequency, spectral broadening). We note that our observation planning system requires that observed targets be sufficiently far away from the Sun to allow us to neglect any spectral broadening due to the interplanetary medium.…”

“…Another solution would be to collapse the data to a lower frequency resolution before applying the tree summation in the algorithm (Siemion et al 2013).…”

“…The potential spectral similarity between anthropogenic radio-frequency interference (RFI) and extraterrestrial technological transmissions brings additional complications. The sheer immensity of the parameter space that must be explored is a potential explanation to the absence of radio detections of extraterrestrial intelligence, despite numerous previous efforts (Verschuur 1973;Tarter et al 1980;Bowyer et al 1983Bowyer et al , 1995Horowitz et al 1986;Steffes & Deboer 1994;Mauersberger et al 1996;Backus 1998;Werthimer et al 2000;Korpela et al 2011;Siemion et al 2013;Harp et al 2016;Gray & Mooley 2017).…”

SETIBURST: A Robotic, Commensal, Realtime Multi-science Backend for the Arecibo Telescope

“…Radio SETI observations started with Drake (1961) who searched for narrow-band linesand have continued to the present day with increasing levels of sophistication. For instance, Siemion et al (2013) recently searched for interplanetary radar signals in multi-planet systems during conjunctions, 11 and established that 1% of transiting exoplanet systems host civilizations that emit narrow-band radiation in the 1-2 GHz band with an equivalent isotropically radiated power (EIRP) of ∼1.5×10 13 W. Whether ETI would set up beacons for the benefit of curious radio astronomers in other civilizations is unknown, but setting up such beacons is the best possible way to advertise our presence in the universe. Radio emission is energetically, and hence, economically inexpensive to generate.…”

“…There is at least one Galactic-origin theory (that also predicts pulse repetition) wherein these bursts originate in flare stars, and are dispersed by the stellar corona (Loeb et al 2014). A resolution of the mystery has been made complicated by two recent discoveries, namely, that of FRB 150418, which has been claimed to be 11 Note the error in the sensitivity calculation in Siemion et al (2013)and the values reported in their 12 https://sites.google.com/site/publicsuperb/ associated with a slow radio transient in an elliptical galaxy interpreted to be an afterglow of a cataclysmic, non-repeating event (Keane et al 2016), and that of FRB 121102,which has been shown to repeat (Spitler et al 2014. 13 Eighteen FRBs have been reported in thepublished literature 14 ).…”