A Spatially Resolved HI Survey of Seyfert Galaxies: the Role of AGN Feedback in Shaping Atomic Gas Reservoirs

TL;DR

This study presents high-resolution HI maps of Seyfert galaxies, showing that AGN feedback may influence atomic gas kinematics but does not significantly alter the overall gas reservoir size or structure.

Contribution

First spatially resolved HI survey of Seyfert hosts revealing detailed gas kinematics and assessing AGN feedback effects on atomic gas reservoirs.

Findings

AGN-host galaxies have a slightly shallower HI mass-size relation.

Elevated velocity dispersion and reduced rotational support in HI disks of Seyfert galaxies.

Evidence suggests AGN-driven outflows may inject turbulence into atomic gas.

Abstract

Active galactic nucleus (AGN) feedback is a key ingredient in galaxy evolution, yet its impact on the cold atomic gas reservoir -- the neutral hydrogen (HI) phase -- remains poorly constrained. We present the most extensive spatially resolved HI 21-cm survey of Seyfert AGN hosts to date, based on observations with the Giant Metrewave Radio Telescope (GMRT). Our high-resolution HI maps of eight Seyfert galaxies reveal detailed kinematics and surface density distributions of their atomic gas disks. We find that AGN-host galaxies exhibit a slightly shallower HI mass-size relation than the canonical relation or the SIMBA simulation predictions; however, the measured slope remains consistent with the canonical value within $2\sigma$ uncertainties. This result suggests that AGN feedback does not significantly disrupt the global extent or large-scale structure of atomic gas reservoirs. To investigate the internal HI kinematics in greater detail, we perform a 3D kinematic forward modeling of the HI disk in UGC 4503. Our analysis reveals an elevated intrinsic velocity dispersion of $\sigma = 14.9^{+6.1}_{-3.8}$ km/s and a reduced level of rotational support, with $V/\sigma = 14.28_{-4.17}^{+4.97}$, compared to large-sample star-forming spirals. These kinematic signatures, together with localized residuals in the velocity field, indicate that AGN-driven outflows or jets may inject or indirectly affect the turbulence in the atomic gas disk, potentially regulating the cold gas reservoir. Future GMRT observations, combined with optical integral-field spectroscopy from MaNGA, will enable quantitative constraints on the role of AGN feedback in regulating star formation efficiency across a larger and more representative galaxy sample.