Molecular Gas Outflow in the Starburst Galaxy NGC 1482

TL;DR

This study images molecular gas in NGC 1482, revealing a starburst-driven biconical outflow with detailed dynamics, distribution, and energetics, highlighting the role of stellar feedback in galactic winds.

Contribution

First high-resolution ALMA imaging of molecular outflow in NGC 1482, providing detailed kinematic and spatial analysis of the wind structure and energetics.

Findings

Molecular gas forms a biconical outflow extending 1.5 kpc from the galaxy center.

Outflow velocity is approximately 100 km/s with a mass outflow rate of about 7 solar masses per year.

The outflow's kinetic energy is around 7×10^54 erg, comparable to the energy from stellar feedback over 10 million years.

Abstract

Galactic winds are essential to regulation of star formation in galaxies. To study the distribution and dynamics of molecular gas in a wind, we imaged the nearby starburst galaxy NGC 1482 in CO ($J=1\rightarrow0$) at a resolution of 1'' ($\approx100$ pc) using the Atacama Large Millimeter/submillimeter Array. Molecular gas is detected in a nearly edge-on disk with a radius of 3 kpc and a biconical outflow emerging from the central 1 kpc starburst and extending to at least 1.5 kpc perpendicular to the disk. In the outflow, CO gas is distributed approximately as a cylindrically symmetrical envelope surrounding the warm and hot ionized gas traced by H$\alpha$ and soft X-rays. The velocity, mass outflow rate, and kinetic energy of the molecular outflow are $v_\mathrm{w}\sim100~\mathrm{km~s^{-1}}$, $\dot{M}_\mathrm{w}\sim7~M_\odot~\mathrm{yr}^{-1}$, and $E_\mathrm{w}\sim7\times10^{54}~\mathrm{erg}$, respectively. $\dot{M}_\mathrm{w}$ is comparable to the star formation rate ($\dot{M}_\mathrm{w}/\mathrm{SFR}\sim2$) and $E_\mathrm{w}$ is $\sim1\%$ of the total energy released by stellar feedback in the past $1\times10^7~\mathrm{yr}$, which is the dynamical timescale of the outflow. The results indicate that the wind is starburst driven.