A search for Extraterrestrial Intelligence (SETI) toward the Galactic Anticenter with the Murchison Widefield Array

TL;DR

This study conducted a low-frequency radio survey toward the Galactic Anticenter using the Murchison Widefield Array, searching for signals from extraterrestrial civilizations near 22 known exoplanets but found no evidence of transmissions.

Contribution

It presents the second systematic SETI survey with the MWA targeting the Galactic Anticenter, improving sensitivity and data processing techniques over previous Galactic Center observations.

Findings

No signals detected at the 5-sigma threshold.

Enhanced sensitivity reduced detection limits by a factor of four.

Survey focused on exoplanets closer than previous Galactic Center study.

Abstract

Following from the results of the first systematic modern low frequency Search for Extraterrestrial Intelligence (SETI) using the Murchison Widefield Array (MWA), which was directed toward a Galactic Center field, we report a second survey toward a Galactic Anticenter field. Using the MWA in the frequency range of 99 to 122 MHz over a three hour period, a 625 sq. deg. field centered on Orion KL (in the general direction of the Galactic Anticenter) was observed with a frequency resolution of 10 kHz. Within this field, 22 exoplanets are known. At the positions of these exoplanets, we searched for narrow band signals consistent with radio transmissions from intelligent civilisations. No such signals were found with a 5-sigma detection threshold. Our sample is significantly different to the 45 exoplanets previously studied with the MWA toward the Galactic Center Tingay et al.(2016), since the Galactic Center sample is dominated by exoplanets detected using microlensing, hence at much larger distances compared to the exoplants toward the Anticenter, found via radial velocity and transit detection methods. Our average effective sensitivity to extraterrestrial transmiter power is therefore much improved for the Anticenter sample. Added to this, our data processing techniques have improved, reducing our observational errors, leading to our best detection limit being reduced by approximately a factor of four compared to our previously published results.