Star-formation in the central kpc of the starburst/LINER galaxy NGC1614

TL;DR

This study provides a detailed high-resolution multi-wavelength analysis of NGC1614, revealing a star-forming ring at 300 pc likely caused by a dynamical resonance, with substantial molecular gas reaching the nucleus, and discusses the nature of its LINER spectrum.

Contribution

It offers new high-resolution multi-wavelength observations of NGC1614, identifying a star-forming ring and analyzing its dynamics and gas distribution, challenging previous propagation scenarios.

Findings

Detected a 300 pc star-forming ring coincident with radio and Paschen-alpha observations.

Estimated the dynamical mass of the ring as 3.1 x 10^9 Msun.

Found substantial molecular gas reaching the nuclear region, suggesting ongoing star formation.

Abstract

A high angular resolution, multi-wavelength study of the LINER galaxy NGC1614 has been carried out. OVRO CO 1-0 observations are presented together with extensive multi-frequency radio continuum and HI absorption observations with the VLA and MERLIN. Toward the center of NGC1614, we have detected a ring of radio continuum emission with a radius of 300 pc. This ring is coincident with previous radio and Paschen-alpha observations. The dynamical mass of the ring based on HI absorption is 3.1 x 10E9 Msun. The peak of the integrated CO 1-0 emission is shifted by 1" to the north-west of the ring center and a significant fraction of the CO emission is associated with a crossing dust lane. An upper limit to the molecular gas mass in the ring region is 1.7 x 10E9 Msun. Inside the ring, there is a north to south elongated 1.4GHz radio continuum feature with a nuclear peak. This peak is also seen in the 5GHz radio continuum and in the CO. We suggest that the R=300 pc star forming ring represents the radius of a dynamical resonance - as an alternative to the scenario that the starburst is propagating outwards from the center into a molecular ring. The ring-like appearance probably part of a spiral structure. Substantial amounts of molecular gas have passed the radius of the ring and reached the nuclear region. The nuclear peak seen in 5GHz radio continuum and CO is likely related to previous star formation, where all molecular gas was not consumed. The LINER-like optical spectrum observed in NGC1614 may be due to nuclear starburst activity, and not to an Active Galactic Nucleus (AGN). Although the presence of an AGN cannot be excluded.