Spatially-Resolved Medium Resolution Spectroscopy of an Interacting E+A (post-starburst) System with the Subaru telescope

TL;DR

This study presents spatially-resolved spectroscopy of a nearby post-starburst galaxy and its companion, revealing galaxy-wide starburst effects triggered by interaction, with detailed kinematic and stellar population insights.

Contribution

It provides the first spatially-resolved spectroscopic analysis of a post-starburst galaxy with a companion, showing galaxy-wide effects rather than central starburst.

Findings

Galaxy-wide Hδ absorption with EW > 7Å

Detection of rotation in the companion galaxy (>175 km/s)

Post-starburst age estimated at 100-500 Myr

Abstract

We have performed a spatially-resolved medium resolution long-slit spectroscopy of a nearby E+A (post-starburst) galaxy system, SDSSJ161330.18+510335.5. This E+A galaxy has an obvious companion galaxy 14kpc in front with the velocity difference of 61.8 km/s. Both galaxies have obviously disturbed morphology We have found that H$\delta$ equivalent width (EW) of the E+A galaxy is greater than 7\AA galaxy wide (8.5 kpc). The E+A galaxy have a weak [OIII] emission (EW$\sim$1\AA) by $\sim$2.6 kpc offset from the peak of the Balmer absorption lines. We detected a rotational velocity in the companion galaxy of $>$175km/s. The progenitor of the companion may have been a rotationally-supported, but yet passive S0 galaxy. The age of the E+A galaxy after quenching the star formation is estimated to be 100-500 Myr, with its centre having slightly younger stellar population. These findings are inconsistent with a simple picture where the dynamical interaction creates infall of the gas reservoir that causes the central starburst/post-starburst. Instead, our results present an important example where the galaxy-galaxy interaction can trigger a galaxy-wide post-starburst phenomena.