An arcsecond view at 1-2 GHz into the Galactic Bulge

TL;DR

This high-resolution radio survey of the Galactic Bulge at 1-2 GHz identified over 1600 sources, including X-ray counterparts, pulsar candidates, and unique objects, enhancing understanding of the region's radio source population.

Contribution

The survey provides the first detailed high-resolution radio map of the Galactic Bulge at 1-2 GHz, revealing diverse sources and potential new astrophysical objects.

Findings

1617 sources detected, including 25 X-ray counterparts

Approximately 100 steep-spectrum pulsar candidates

Identification of unique objects like a binary and a transient

Abstract

We present the results of a high angular resolution (1.1") and sensitivity (maximum of ~0.1 mJy) radio survey at 1-2 GHz in the Galactic Bulge. This complements the X-ray Chandra Galactic Bulge Survey, and investigates the full radio source population in this dense Galactic region. Radio counterparts to sources at other wavelengths can aid in classification, as there are relatively few types of objects that are reasonably detectable in radio at kiloparsec distances, and even fewer that are detected in both X-rays and radio. This survey covers about 3 square degrees of the Galactic Bulge Survey area (spanning the Galactic coordinate range of -3deg < l < +3deg and +1.6deg < b < +2.1deg as a first look into this region of the Galaxy with this combination of frequency, resolution, and sensitivity. Spectral indices within the observed band of 1-2 GHz were calculated for each source to assist in determining its emission mechanism. We find 1617 unique sources in the survey, 25 of which are radio counterparts to X-ray sources, and about 100 of which are steep-spectrum (alpha <~ -1.4) point sources that are viable pulsar candidates. Four radio sources are of particular interest: a compact binary; an infrared transient with an inverted radio spectrum; a potential transitional millisecond pulsar candidate; and a very steep spectrum radio source with an X-ray and bright infrared counterpart. We discuss other notable sources, including possible radio transients, potential new planetary nebulae, and active galactic nuclei.