HI gas in the rejuvenated radio galaxy 4C29.30

TL;DR

This study presents GMRT observations of HI absorption in the rejuvenated radio galaxy 4C29.30, revealing complex gas dynamics that may fuel recent radio activity and indicating a link between HI presence and galaxy rejuvenation.

Contribution

First detailed HI absorption analysis of 4C29.30, showing multiple components and suggesting gas fueling rejuvenated radio activity.

Findings

HI absorption profile has six components, mostly red-shifted.

Detected neutral hydrogen column density is high, indicating substantial gas presence.

Red-shifted gas may be fueling the galaxy's recent activity.

Abstract

We report the results of our observations of HI absorption towards the central region of the rejuvenated radio galaxy 4C29.30 (J0840+2949) with the Giant Metrewave Radio Telescope (GMRT). The radio source has diffuse, extended emission with an angular size of $\sim$520 arcsec (639 kpc) within which a compact edge-brightened double-lobed source with a size of 29 arcsec (36 kpc) is embedded. The absorption profile which is seen towards the central component of the inner double is well resolved and consists of six components; all but one of which appears to be red-shifted relative to the optical systemic velocity. The neutral hydrogen column density is estimated to be $N$(HI)=4.7$\times10^{21}$($T_s$/100)($f_c$/1.0) cm$^{-2}$, where $T_s$ and $f_c$ are the spin temperature and covering factor of the background source respectively. This detection reinforces a strong correlation between the occurrence of HI absorption and rejuvenation of radio activity suggested earlier, with the possibility that the red-shifted gas is fuelling the recent activity.