Radio jet-ISM interaction and positive radio-mechanical feedback in Abell 1795

TL;DR

This study combines multi-wavelength observations to explore how radio jets in Abell 1795's brightest galaxy influence star formation and gas dynamics, revealing both quenching and triggering effects through shock-driven turbulence.

Contribution

It provides new insights into the dual role of radio jets in heating and triggering star formation, with detailed analysis of gas kinematics and ionization sources.

Findings

Star formation rate of 9.3 M$_\ m\odot$ yr$^{-1}$ following Kennicutt-Schmidt law.

Detection of shock fronts and turbulence driven by radio jets.

Evidence of positive feedback where jets trigger star formation.

Abstract

We present XSHOOTER observations with previous ALMA, MUSE and $HST$ observations to study the nature of radio-jet triggered star formation and the interaction of radio jets with the interstellar medium in the brightest cluster galaxy (BCG) in the Abell 1795 cluster. Using $HST$ UV data we determined an ongoing star formation rate of 9.3 M$_\odot$ yr$^{-1}$. The star formation follows the global Kennicutt-Schmidt law, however, it has a low efficiency compared to circumnuclear starbursts in nearby galaxies with an average depletion time of $\sim$1 Gyr. The star formation and molecular gas are offset by $\sim1$ kpc indicating that stars have decoupled from the gas. We detected an arc of high linewidth in ionized gas where electron densities are elevated by a factor of $\sim$4 suggesting a shock front driven by radio jets or peculiar motion of the BCG. An analysis of nebular emission line flux ratios suggests that the gas is predominantly ionized by star formation with a small contribution from shocks. We also calculated the velocity structure function (VSF) of the ionized and molecular gases using velocity maps to characterize turbulent motion in the gas. The ionized gas VSF suggests that the radio jets are driving supersonic turbulence in the gas. Thus radio jets can not only heat the atmosphere on large scales and may quench star formation on longer timescales while triggering star formation in positive feedback on short timescales of a few million years.