Resolving double-peaked emission line galaxies using MaNGA

I. Mechanisms of star formation quenching

¹ Observatoire de Paris, PSL University, CNRS, Sorbonne Université, LERMA, 75014 Paris, France
² Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia
³ ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), Australia
⁴ Collège de France, 11 Place Marcelin Berthelot, 75005 Paris, France
⁵ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA

Received: 13 December 2021
Accepted: 2 July 2024

Abstract

Understanding the relationship between quenching mechanisms that transform star-forming galaxies into quiescent ones and galaxy properties remains a challenge. We investigate the gas and stellar properties of 69 double-peaked galaxies selected from the Sloan Digital Sky Survey (SDSS) and observed as part of the Mapping Nearby Galaxies at APO (MaNGA) survey to elucidate the mechanisms driving star formation quenching within these systems. We study their star formation activity along with their physical properties: colour, morphology, environment, stellar age, and gas ionisation diagnostics. We find that these 69 double-peaked MaNGA galaxies encompass a higher fraction of galaxies in the green valley, based on the corrected NUV − r colour, compared to our defined control samples of single-peaked emission line galaxies. This green colour traces intermediate stellar populations compared to blue and red galaxies, as indicated by the D_n(4000) index. These green galaxies show no recent star formation bursts within the last 2 Gyr. They exhibit emission line ratios that are suggestive of both ongoing star formation and nuclear activity. They are predominantly located in isolated or small group environments, indicating that internal processes rather than external factors drive their quenching. Moreover, optical emission lines detected throughout a significant area of these systems suggest that gas depletion is unlikely to be the primary quenching mechanism. These findings support a scenario where quenching is instead caused by reduced star formation efficiency.