Variable and Transient Radio Sources in the FIRST Survey

TL;DR

This study analyzed approximately 55,000 radio images from the FIRST survey, discovering 1,627 variable and transient sources across various timescales, revealing diverse astrophysical objects and many with unknown counterparts.

Contribution

It provides the first large-scale catalog of variable and transient radio sources, identifying new objects and highlighting the need for multi-wavelength follow-up.

Findings

Discovered 1,627 variable/transient sources in radio data.

Variability spans from 20% to 25-fold changes.

Over half lack counterparts at other wavelengths.

Abstract

A comprehensive search for variable and transient radio sources has been conducted using ~55,000 snapshot images of the FIRST survey. We present an analysis leading to the discovery of 1,627 variable and transient objects down to mJy levels over a wide range of timescales (few minutes to years). Variations observed range from 20% to a factor of 25. Multi-wavelength matching for counterparts reveals the diverse classes of objects exhibiting variability, ranging from nearby stars and pulsars to galaxies and distant quasars. Interestingly, more than half of the objects in the sample have either no classified counterparts or no corresponding sources at any other wavelength and require multi-wavelength follow-up observations. We discuss these classes of variables and speculate on the identity of objects that lack multi-wavelength counterparts.