High-resolution radio observations of nuclear and circumnuclear starbursts in Luminous Infrared Galaxies

TL;DR

This paper presents high-resolution radio observations of luminous infrared galaxies to study their nuclear starbursts, revealing structures that help understand star formation and supernova activity in these dusty, active regions.

Contribution

It provides new high-resolution radio data of LIRGs, identifying compact sources and supernovae, advancing understanding of star formation and nuclear activity in these galaxies.

Findings

Detection of compact radio sources in LIRGs

Identification of bright radio supernovae

Implications for star-formation rates

Abstract

High-resolution radio observations of nearby starburst galaxies have shown that the distribution of their radio emission consists of a compact (<150 pc), high surface brightness, central radio source immersed in a low surface brightness circumnuclear halo. This radio structure is similar to that detected in bright Seyferts galaxies like NGC 7469 or Mrk 331, which display clear circumnuclear rings. While the compact, centrally located radio emission in these starbursts might be generated by a point-like source (AGN), or by the combined effect of multiple radio supernovae and supernova remnants (e.g., the evolved nuclear starburst in Arp~220), it seems well established that the circumnuclear regions of those objects host an ongoing burst of star-formation (e.g., NGC 7469; Colina et al. 2001, Alberdi et al. 2006). Therefore, high-resolution radio observations of Luminous Infra-Red Galaxies (LIRGs) in our local universe are a powerful tool to probe the dominant dust heating mechanism in their nuclear and circumnuclear regions. In this contribution, we show results obtained from VLA-A, MERLIN, and EVN (VLBI) radio observations of the galaxies NGC 7469 (D~70 Mpc) and IRAS 18293-3413 (D ~ 79 Mpc), where two extremely bright radio supernovae have been found. High-resolution studies of these and other LIRGs would allow us to determine the core-collapse supernova rate in them, as well as their star-formation rate.