Unveiling the Bulge-Disc Structure, AGN Feedback, and Baryon Landscape in a Massive Spiral Galaxy with Mpc-Scale Radio Jets

Kavli Affiliate: Luis C. Ho

| First 5 Authors: Joydeep Bagchi, Shankar Ray, Suraj Dhiwar, Pratik Dabhade, Aaron Barth

| Summary:

This study delves into the bulge-disc components and stellar mass
distribution in the fast-rotating, highly massive spiral galaxy
2MASX~J23453268-0449256, distinguished by extraordinary radio jets extending to
Mpc scales. Using high-resolution multi-wavelength Hubble Space Telescope (HST)
observations and multi-parameter panchromatic spectral energy distribution
(SED) fitting, we derive estimates for the star formation rate, total baryonic
mass in stars, and warm dust properties. Our findings, validated at a spatial
resolution of approximately 100 pc, reveal a pseudo-bulge rather than a
classical bulge and a small nuclear bar and resonant ring, challenging
conventional models of galaxy formation. Additionally, the lack of tidal debris
and the highly symmetric spiral arms within a rotationally supported stellar
disc indicate a tranquil coevolution of the galactic disc and its supermassive
black hole (SMBH). Significantly, the galaxy exhibits suppressed star formation
in its center, potentially influenced by feedback from the central accreting
SMBH with powerful radio jets. Detailed multi-wavelength studies of potential
star-forming gas disclose that, while hot X-ray gas cools down in the galaxy’s
halo, new stars do not form in the center, likely due to feedback effects. This
study raises questions about the efficient fueling and sustained collimated jet
ejection activity in J2345-0449, underscoring the imperative need for a
comprehensive understanding of its central black hole engine properties, which
are presently lacking. The exceptional rarity of galaxies like
2MASX~J23453268-0449256 presents intriguing challenges in unraveling the
physical processes responsible for their unique characteristics.

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