Tracing the Energetic Outflows from Galactic Nuclei: Observational Evidence for a Large-Scale Bipolar Radio and X-ray-emitting Bubble-like Structure in M106

TL;DR

This paper presents observational evidence of a large bipolar bubble structure in galaxy M106, revealing insights into galactic nuclear feedback and its role in shaping the circumgalactic medium.

Contribution

It provides the first detailed observational analysis of a bipolar radio/X-ray bubble in M106, constraining its physical properties and energy sources.

Findings

The bubbles contain hot plasma with an estimated thermal energy of ~8 x 10^56 erg.

The structure's energy likely originates from past AGN activity with an average power of ~4 x 10^42 erg/s.

Evidence of a hot galactic corona suggests widespread diffuse X-ray emission.

Abstract

The role of energetic outflows from galactic nuclei in shaping galaxy formation and evolution is still shrouded in uncertainty. In this study, we shed light on this complex phenomenon by presenting evidence for a large-scale bipolar radio/X-ray-emitting bubble-like structure emanating from the central region of the nearby disk galaxy M106 (NGC 4258). Our findings, based on Low-Frequency Array survey data and Chandra observations, provide a glimpse into the underlying physical processes driving this enigmatic structure. Similar to the eROSITA/Fermi bubbles in our own Galaxy, the M106 bubbles enclose diffuse hot plasma and are partially bounded by prominent radio/X-ray-emitting edges. We constrain the magnetic field and cosmic-ray properties of the structure. The analysis of the X-ray data gives an estimate of the thermal energy of the bubbles as ~8 x 10^56 erg. This energy can be supplied by the jets and perhaps by the wind from the accretion flow of the galaxy's low-luminosity AGN, which most likely has been much more powerful in the recent past, with an average mechanical energy release rate of ~4 x 10^42 erg/s over the last ~ 8 x 10^6 yr -- the estimated age of the structure. We also show evidence for diffuse X-ray emission on larger scales, indicating the presence of a hot galactic corona. Our results provide a clear manifestation of galactic nuclear feedback regulating the gas content and energetics of the circumgalactic medium of disk galaxies similar to our own.