Investigating the nuclear activity of barred spiral galaxies: the case of NGC 1672

TL;DR

This study uses multiwavelength data to analyze the nuclear activity of the barred spiral galaxy NGC 1672, revealing a low-luminosity AGN and the influence of the bar on star formation and X-ray sources.

Contribution

First detailed multiwavelength analysis of NGC 1672's nuclear region demonstrating the presence of a LLAGN influenced by the galaxy's bar structure.

Findings

Detection of a hard nuclear X-ray source consistent with a LLAGN

Identification of 28 X-ray sources, including ULXs at the bar ends

Presence of a circumnuclear star-forming ring dominating central X-ray emission

Abstract

We have performed an X-ray study of the nearby barred spiral galaxy NGC1672, primarily to ascertain the effect of the bar on its nuclear activity. We use both Chandra and XMM-Newton observations to investigate its X-ray properties, together with supporting high-resolution optical imaging data from the Hubble Space Telescope (HST), infrared imaging from the Spitzer Space Telescope, and ATCA ground-based radio data. We detect 28 X-ray sources within the D25 area of the galaxy, many of which correlate spatially with star-formation in the bar and spiral arms, while two are identified as background galaxies in the HST images. Nine of the X-ray sources are ULXs, with the three brightest (LX > 5E39 erg/s) located at the ends of the bar. With the spatial resolution of Chandra, we are able to show for the first time that NGC1672 possesses a hard (Gamma~1.5) nuclear X-ray source with a 2-10 keV luminosity of 4E38 erg/s. This is surrounded by an X-ray bright circumnuclear star-forming ring, comprised of point sources and hot gas, which dominates the 2-10 keV emission in the central region of the galaxy. The spatially resolved multiwavelength photometry indicates that the nuclear source is a low-luminosity AGN (LLAGN), but with star formation activity close to the central black hole. A high-resolution multiwavelength survey is required to fully assess the impact of both large-scale bars and smaller-scale phenomena such as nuclear bars, rings and nuclear spirals on the fueling of LLAGN.