A Search for Optical Laser Emission from Alpha Centauri AB

TL;DR

A comprehensive search for optical laser emissions from Alpha Centauri A and B using high-resolution spectra from 2004 to 2018 found no evidence of extraterrestrial laser signals, setting power thresholds for detection.

Contribution

This study provides the first extensive optical spectral survey of Alpha Centauri for laser signals, establishing detection thresholds and highlighting the scarcity of detectable extraterrestrial laser emissions.

Findings

No laser emission lines detected in 15,362 spectra.

Detection thresholds ranged from 1.4 to 5.4 MW depending on wavelength.

The search constrains the prevalence of detectable extraterrestrial laser technology.

Abstract

A search for laser light from the directions of Alpha Centauri A and B was performed by examining 15362 optical, high-resolution spectra obtained between 2004 and 2018. None of the spectra exhibit laser emission lines. The threshold was 10% of the continuum intensity of the spectra of both stars at all wavelengths between 3850 and 6900 {\AA}. This search would have revealed optical laser light from the directions of Alpha Cen B if the laser had a power at least 1.4 to 5.4 MW (depending on wavelength) and was positioned within the 1 arcsecond field of view (projecting to 1.3 AU), for a benchmark 10-meter laser launcher. For Alpha Cen A, the laser power must be 3 times greater for detection. Lasers of smaller aperture would also have been detected but would require more power. Considering all optical surveys, a growing desert is emerging in the search for extraterrestrial technology.