Tracing the Milky Way's Vestigial Nuclear Jet

TL;DR

This study combines multi-wavelength observations and hydrodynamical simulations to trace a weak, historical jet from the Galactic Center, explaining large-scale structures like X-ray and gamma-ray bubbles as jet-driven outflows.

Contribution

It provides a comprehensive multi-modal analysis and modeling of the Milky Way's vestigial nuclear jet, linking it to observed large-scale energetic bubbles.

Findings

A weak jet from Sgr A* can produce observed bipolar structures.

Hydrodynamical models support jet-driven inflation of X-ray and gamma-ray bubbles.

Evidence suggests a historical Seyfert-level outburst shaped the Galactic Center features.

Abstract

MeerKAT radio continuum and XMM-Newton X-ray images have recently revealed a spectacular bipolar channel at the Galactic Center that spans several degrees ($\sim$0.5 kpc). An intermittent jet likely formed this channel and is consistent with earlier evidence of a sustained, Seyfert-level outburst fueled by black-hole accretion onto Sgr A$^*$ several Myr ago. Therefore, to trace a now weak jet that perhaps penetrated, deflected, and percolated along multiple paths through the interstellar medium, relevant interactions are identified and quantified in archival X-ray images, Hubble Space Telescope Paschen $\alpha$ images and Atacama Large Millimeter/submillimeter Array millimeter-wave spectra, and new SOAR telescope IR spectra. Hydrodynamical simulations are used to show how a currently weak jet can explain these structures and inflate the ROSAT/eROSITA X-ray and Fermi $\gamma$-ray bubbles that extend $\pm75\deg$ from the Galactic plane. Thus, our Galactic outflow has features in common with energetic, jet-driven structures in the prototypical Seyfert galaxy NGC 1068.