Probing the high frequency variability of NGC 5044: the key to AGN feedback

TL;DR

This study investigates the high-frequency variability of NGC 5044's AGN using multi-wavelength observations, revealing a 150-day variability timescale that constrains the accretion and jet emission regions, advancing understanding of AGN feedback mechanisms.

Contribution

It provides the first detailed variability analysis of NGC 5044's AGN at high frequencies, constraining emission region sizes and magnetic fields, and supports the ADAF and jet emission models.

Findings

Variability timescale of 150 days identified.

Emission region constrained to about 0.1 parsecs.

Magnetic field strengths estimated at 4.7 mG in jets and 870 G in the accretion disk.

Abstract

The active galactic nucleus (AGN) feeding and feedback process in the centers of galaxy clusters and groups is still not well understood. NGC 5044 is the ideal system in which to study AGN feedback. It hosts the largest known reservoir of cold gas in any cool-core galaxy group, and features several past epochs of AGN feedback imprinted as cavities in the X-ray bright intragroup medium (IGrM), as well as parsec scale jets. We present Submillimeter Array (SMA), Karl G. Jansky Very Large Array (VLA), James Clerk Maxwell Telescope (JCMT), and Atacama Large Millimeter/submillimeter Array (ALMA) high frequency observations of NGC 5044 to assess the time variability of the mmwaveband emission from the accretion disk, and quantify the Spectral Energy Distribution (SED) from the radio to sub-millimeter band. The SED is well described by advection dominated accretion flow (ADAF) model and self-absorbed jet emission from an aging plasma with tau = 1kyr. We find a characteristic variability timescale of 150 days, which constrains the ADAF emission region to about 0.1pc, and the magnetic field to 4.7mG in the jets and and 870G in the accretion disk. A longer monitoring/sampling will allow to understand if the underlying process is truly periodic in nature.