High resolution radio analysis of the starburst galaxy NGC 4527: signatures of an AGN core

TL;DR

This study uses new radio observations to analyze the structure of NGC 4527, revealing signs of a low-luminosity AGN and star-forming regions, and proposing a model of accretion-driven star formation.

Contribution

It provides high-resolution radio imaging of NGC 4527, identifying an AGN core and star-forming ring, and suggests a new scenario involving super-Eddington accretion and wind-driven star formation.

Findings

Detection of an AGN core with low luminosity

Identification of a star formation ring coincident with molecular gas

Evidence supporting super-Eddington accretion driving circumnuclear star formation

Abstract

NGC 4527 is a nearby edge-on spiral galaxy with both starburst and AGN features, hosting a LINER nucleus. We present a radio study of the large-scale structure and nuclear region of this galaxy, based on new uGMRT observations at 700 and 1230 MHz. Our continuum maps reveal extended emission tracing the stellar disk, with no evidence of a radio halo. The spectral index distribution and the presence of PAHs across the disk are consistent with ongoing star formation. In the nuclear region we resolve three compact sources: one at the galactic centre and two symmetrically aligned with the major axis at $\sim400$ pc. The spectral index values and the destruction of PAHs in the central source, together with previously detected X-rays emission, suggest the presence of a low-luminosity AGN. The two off-centre sources are consistent with a star formation ring, coincident with a molecular gas ring previously reported. We explore a scenario where super-Eddington accretion onto the black hole drives a dense wind that falls back onto the disk, triggering star formation in a circumnuclear ring.