Spatially Resolved Studies of Local Massive Red Spiral Galaxies

TL;DR

This study uses two-dimensional spectroscopy to analyze massive red spiral galaxies, revealing their stellar properties are more akin to elliptical galaxies than blue spirals, suggesting a merger-based formation history.

Contribution

It provides the first detailed spectroscopic comparison of massive red spirals with ellipticals and blue spirals, highlighting their similar stellar populations and potential merger origins.

Findings

Red spirals have older stellar populations than blue spirals.

Red spirals exhibit higher metallicity and Mgb/Fe ratios.

Their properties suggest formation through gas-rich major mergers.

Abstract

We report two-dimensional spectroscopic analysis of massive red spiral galaxies ($M_{*}$ $>$ 10$^{10.5}$ $M_{\odot}$) and compare them to blue spiral and red elliptical galaxies above the same mass limit based on the public SDSS DR15 MaNGA observations. We find that the stellar population properties of red spiral galaxies are more similar to those of elliptical galaxies than to blue spiral galaxies. Red spiral galaxies show a shallow mass-weighted age profile, and they have higher stellar metallicity and Mgb/${\rm \langle Fe \rangle}$ across the whole 1.5$R_{\rm e}$ as compared to blue spirals, but all these properties are close to those of elliptical galaxies. One scenario to explain this is that red spirals form as remnants of very gas-rich major mergers that happened above $z$$\sim$1.