| In a recent paper, an international team of scientists, including several researchers from ASTRON and JIVE, discussed the exciting prospects for conducting searches for extraterrestrial intelligence (SETI) with the Square Kilometre Array (SKA). This image is a composite of several figures from this work.
Absent of the actual detection of an artificial extraterrestrial radio transmitter, our best points of reference for the sensitivity of radio SETI experiments, and the luminosities of sources we might detect, come from our own terrestrial technology. Several terrestrial transmitters that produce emission in the bands probed by the SKA, along with their pseudo-luminosities as described by their equivalent isotropically radiated power (EIRP), are listed above the two plot panels.
The upper panel depicts the sensitivity of each component of the SKA to narrow-band transmitters at 15 pc, as compared with other facilities actively performing SETI searches over the same band. Search parameter assumptions here match roughly what might be expected for a significant fraction of commensal (or "piggy-back") observations, namely a maximum integration time of 10 minutes. In the upper panel, a transmitter is detectable if its EIRP is above the curve for a given telescope. Thus in the observing scenario presented, a transmitter with an EIRP of 2 x 10^20 ergs/sec (planetary radar) is detectable with all of the telescopes shown, while a transmitter with an EIRP of 1 x 10^17 ergs/sec (airport radar) is detectable only with SKA2.
The lower plot panel depicts what sensitivities could be attained in a more optimistic scenario, in which SETI was the primary observing purpose or commensal observations were performed with another science case very well matched to SETI. Here we assume an integration time of 60 minutes, and the minimum channelization bandwidth permitted by ISM and IPM effects. As shown, with SKA1, radio transmitter luminosities similar to our high power radars will be detectable from tens of thousands of stars across the entire terrestrial microwave window, and with SKA2 these signals will be detectable from hundreds of thousands of stars. Further, with SKA2 we will for the first time have the sensitivity to detect radio emission similar in power to our own TV and radio stations from a few of our nearest neighbors.