The nuclear activity and central structure of the elliptical galaxy NGC 5322

Abstract

We have analysed a new high-resolution e-MERLIN 1.5 GHz radio continuum map together with $HST$ and SDSS imaging of NGC 5322, an elliptical galaxy hosting radio jets, aiming to understand the galaxy's central structure and its connection to the nuclear activity. We decomposed the composite $HST$ + SDSS surface brightness profile of the galaxy into an inner stellar disc, a spheroid, and an outer stellar halo. Past works showed that this embedded disc counter-rotates rapidly with respect to the spheroid. The $HST$ images reveal an edge-on nuclear dust disc across the centre, aligned along the major-axis of the galaxy and nearly perpendicular to the radio jets. After careful masking of this dust disc, we find a central stellar mass deficit $M_{\mathrm{def}}$ in the spheroid, scoured by SMBH binaries with final mass $M_{\mathrm{BH}}$ such that $M_{\mathrm{def}}/M_{\mathrm{BH}}\sim 1.3-3.4$. We propose a three-phase formation scenario for NGC 5322 where a few ($2-7$) "dry" major mergers involving SMBHs built the spheroid with a depleted core. The cannibalism of a gas-rich satellite subsequently creates the faint counter-rotating disc and funnels gaseous material directly onto the AGN, powering the radio core with a brightness temperature of $T_{\mathrm{B},\mathrm{core}}\sim 4.5\times 10^7$ K and the low-power radio jets ($P_{\mathrm{jets}}\sim 7.04\times 10^{20}$ W Hz${}^{-1}$) which extend $\sim 1.6$ kpc. The outer halo can later grow via minor mergers and the accretion of tidal debris. The low-luminosity AGN/jet-driven feedback may have quenched the late-time nuclear star formation promptly, which could otherwise have replenished the depleted core.

14 pages, 5 figures, accepted for publication in MNRAS

References in corpus (26)

• The ACS Virgo Cluster Survey. VIII. The Nuclei of Early-Type Galaxies
• The Dual Origin of Stellar Halos
• Ejection of Supermassive Black Holes from Galaxy Cores
• The role of mergers and halo spin in shaping galaxy morphology
• The SAURON project - VIII. OASIS/CFHT integral-field spectroscopy of elliptical and lenticular galaxy centres
• Dissipation and Extra Light in Galactic Nuclei: I. Gas-Rich Merger Remnants
• Intracluster light and the extended stellar envelopes of cD galaxies: An analytical description
• Dissipation and Extra Light in Galactic Nuclei: III. 'Core' Ellipticals and 'Missing' Light
• The answer is blowing in the wind: Simulating the interaction of jets with dynamic cluster atmospheres
• The accretion mechanism in low-power radio galaxies
• A consistent measure of the merger histories of massive galaxies using close-pair statistics I: Major mergers at $z<3.5$
• The stellar accretion origin of stellar population gradients in massive galaxies at large radii
• The Cluster Velocity Dispersion of the Abell 2199 cD Halo of NGC 6166
• The host galaxy/AGN connection in nearby early-type galaxies. A new view of the origin of the radio-quiet/radio-loud dichotomy?
• The supermassive black hole of Fornax A
• Recent star formation in nearby 3CR radio-galaxies from UV HST observations
• A remarkably large depleted core in the Abell 2029 BCG IC 1101
• Radio jets in NGC 4151: where eMERLIN meets HST
• A New Channel for the Formation of Kinematically Decoupled Cores in Early-type galaxies
• Companions to Isolated Elliptical Galaxies: Revisiting the Bothun-Sullivan Sample
• Disky elliptical galaxies and the allegedly over-massive black hole in the compact massive `ES' galaxy NGC 1271
• Complex central structures suggest complex evolutionary paths for barred S0 galaxies
• Core shapes and orientations of core-Sersic galaxies
• A High-Resolution Radio Continuum Study Of The Dwarf Irregular Galaxy IC 10
• The e-MERLIN Data Reduction Pipeline
• Star Formation of Merging Disk Galaxies with AGN Feedback Effects

Cited by in corpus (5)

• LeMMINGs. II. The e-MERLIN legacy survey of nearby galaxies. The deepest radio view of the Palomar sample on parsec scale
• The (black hole mass)-(color) relations for early- and late-type galaxies: red and blue sequences
• Ultramassive black holes in the most massive galaxies: $M_{\mathrm{BH}}-\sigma$ versus $M_{\mathrm{BH}}-R_{\mathrm{b}}$
• Unveiling the 100 pc scale nuclear radio structure of NGC 6217 with e-MERLIN and the VLA
• The most massive galaxies with large depleted cores: structural parameter relations and black hole masses