Forming Stars in a Dual AGN Host: Molecular and Ionized Gas in the Nearby, Luminous Infrared Merger, Mrk 266

TL;DR

This study investigates star formation in the merging galaxy system Mrk 266, combining molecular and ionized gas observations to assess current and future star formation rates and the impact of the merger on galaxy evolution.

Contribution

It provides detailed measurements of molecular and ionized gas in Mrk 266, revealing the galaxy's star formation activity and gas content during a merger with dual active nuclei.

Findings

Mrk 266 has a total H2 mass of approximately 1.1×10^10 M_sun.

Current star formation rate is estimated at about 15 M_sun/yr.

The system has enough molecular gas to sustain star formation for several hundred million years.

Abstract

We present star formation rates based on cold and ionized gas measurements of Mrk 266 (NGC 5256), a system composed of two colliding gas-rich galaxies, each hosting an active galactic nucleus. Using $^{12}$CO (1-0) observations with the Combined Array for Research in Millimeter-Wave Astronomy (CARMA), we find a total H$_2$ mass in the central region of $1.1\pm0.3\times10^{10}$ $M_\odot$ which leads to a possible future star formation rate of $25\pm10 M_\odot$ yr$^{-1}$. With the Fourier Transform Spectrograph (SITELLE) on the Canada-France-Hawaii Telescope, we measure an integrated H$\alpha$ luminosity and estimate a present-day star formation rate of $15\pm2 M_\odot$ yr$^{-1}$ in the core of the system (avoiding the two active nuclei). These results confirm that Mrk 266 is an intermediate stage merger with a relatively high recent star formation rate and enough molecular gas to sustain it for a few hundred million years. Inflowing gas associated with the merger may have triggered both the starburst episode and two AGN but the two galaxy components differ: the region around the SW nucleus appears to be more active than the NE nucleus, which seems relatively quiet. We speculate that this difference may originate in the properties of the interstellar medium in the two systems.