Imaging and photometric studies of NGC 1316 (Fornax A) using Astrosat/UVIT

TL;DR

This study uses AstroSat's UV imaging to analyze NGC 1316, revealing features of gas acquisition, star formation rates, and AGN influence, indicating ongoing galaxy settling and quenching processes.

Contribution

First UV imaging analysis of NGC 1316 with AstroSat revealing detailed features of gas, star formation, and AGN effects in a radio galaxy.

Findings

UV emission features indicate merger history and gas acquisition.

Star formation rates are estimated at 0.15 and 0.36 M$_ ext{sun}$yr$^{-1}$.

AGN-driven outflows likely contribute to star formation quenching.

Abstract

We present imaging and photometric studies of the radio galaxy NGC 1316 (Fornax~A) using high spatial resolution near-ultraviolet (NUV) and far-ultraviolet (FUV) imaging telescopes of the first Indian multi-wavelength space observatory {\it AstroSat}. The residual maps of UV emission obtained from the subtraction of smooth models witness peculiar features within the central few kpc (1-2 kpc) region. The spatial correspondence between the radio emission maps and FUV imaging study reveal that the UV emitting sources are displaced away from the centre by the AGN outburst (radio jet). The presence of rims and clumpy structures in the outskirt of this galaxy delineate that the galaxy has acquired a large fraction of gas through merger-like events and is still in the process of settling. The estimates of the star formation rates (SFR) using FUV and NUV luminosities are found to be 0.15 M$_\odot$yr$^{-1}$ and 0.36 M$_\odot$yr$^{-1}$, respectively, and provide the lower limit due to the screen effect. The estimated lower rates of SFR in this galaxy probably represent its quenching due to the AGN driven outflows emanating from the central engine of NGC 1316.