An integral field spectroscopic study of stellar and ionized gas properties around edge-on disk galaxies in the stellar mass range 9<log M*<11

TL;DR

This study uses integral field spectroscopy to analyze stellar and ionized gas properties in edge-on disk galaxies, revealing correlations between stellar populations, disk structure, and star formation activity across different galaxy masses.

Contribution

It provides new insights into the vertical stellar population profiles and ionization mechanisms in edge-on galaxies, highlighting the role of galaxy mass and accretion history.

Findings

More massive galaxies have more extended thick disks.

Older stellar populations are common in thick disks, with some showing younger populations.

Ionization from evolved stars likely influences emission line ratios in the halo.

Abstract

We analyze the stellar light, 4000 Angstrom break and emission line profiles of 82 edge-on disk galaxies from the MaNGA survey. We characterize the stellar light profiles perpendicular to the disk plane using two parameters: a) the power law slope of the thick disk component, 2) the transition radius where the profile flattens. The 4000 Angstrom break profiles perpendicular to the plane are characterized by the number of significant changes in slope (breaks) and by the change in D_n(4000) from inner to outer disk. The slope correlates tightly with the stellar mass of the galaxy over the stellar mass range 10^9<log M*<10^10 M_sun. More massive galaxies have more extended thick disks. The slope and transition radius exhibit large scatter for galaxies more massive than 10^{10} M_sun. Half the sample have older stellar populations in their thick disks, a third have flat D$_n$(4000) profiles and 15% have younger thick disks. The D$_n$(4000) profiles exhibit as many as 4 separate breaks. There are more breaks in massive galaxies with bulges and more extended thick disks. This may indicate that the breaks are produced by more frequent accretion events in such systems. The extra-planar Halpha EQW correlates most strongly with the specific star formation rate of the galaxy, and the [OII]/Halpha ratio increases with distance from the disk plane. This increase is most apparent for massive galaxies with extended thick disk components and low SFR/M* These findings support the hypothesis that the larger [OII]/Halpha ratios may be caused by ionization from evolved stars.