# Nuclear Spiral Shocks and Induced Gas Inflows in Weak Oval Potentials

## TL;DR

This study uses high-resolution hydrodynamic simulations to analyze how weak oval potentials in galaxy centers can generate nuclear spirals and shocks, leading to gas inflows that may fuel black hole activity.

## Contribution

It demonstrates that even weak bar-like potentials can produce significant nuclear spirals and shocks, influencing gas inflow rates in galaxy centers.

## Key findings

- Weak potentials can induce shocks at small radii.
- Low shear results in loosely wound spirals and higher inflow.
- High shear produces tightly wound spirals and circumnuclear disks.

## Abstract

Nuclear spirals are ubiquitous in galaxy centers. They exist not only in strong barred galaxies but also in galaxies without noticeable bars. We use high-resolution hydrodynamic simulations to study the properties of nuclear gas spirals driven by weak bar-like and oval potentials. The amplitude of the spirals increases toward the center by a geometric effect, readily developing into shocks at small radii even for very weak potentials. The shape of the spirals and shocks depends rather sensitively on the background shear. When shear is low, the nuclear spirals are loosely wound and the shocks are almost straight, resulting in large mass inflows toward the center. When shear is high, on the other hand, the spirals are tightly wound and the shocks are oblique, forming a circumnuclear disk through which gas flows inward at a relatively lower rate. The induced mass inflow rates are enough to power black hole accretion in various types of Seyfert galaxies as well as to drive supersonic turbulence at small radii.