Structural Parameters of Stellar Disks from 2MASS Images of Edge-on Galaxies

TL;DR

This study analyzes near-infrared images of 139 edge-on spiral galaxies to determine their stellar disk parameters, correct for extinction, and explore their mass ratios and structural properties.

Contribution

It provides new measurements of disk scaleheight, scalelength, and brightness in multiple NIR bands, and estimates dark-to-luminous mass ratios using a simplified galactic model.

Findings

Extinction-corrected scaleheight is about 11% smaller than in K-band.

Dark-to-luminous mass ratio averages 1.3.

Disk thickness correlates with face-on surface brightness.

Abstract

We present results of an analysis of the J, H, and K$_s$ 2MASS images of 139 spiral edge-on galaxies selected from the Revised Flat Galaxies Catalog. The basic structural parameters scalelength (h), scaleheight (z_0), and central surface brightness of the stellar disks (mu_0) are determined for all selected galaxies in the NIR bands. The mean relative ratios of the scaleheights of the thin stellar disks in the J:H:K$_s$ bands are 1.16:1.08:1.00, respectively. Comparing the scaleheights obtained from the NIR bands for the same objects, we estimate the scaleheights of the thin stellar disks corrected for the internal extinction. We find that the extinction-corrected scaleheight is, on average, 11% smaller than that in the K-band. Using the extinction-corrected structural parameters, we find that the dark-to-luminous mass ratio is, on average, 1.3 for the galaxies in our sample within the framework of a simplified galactic model. The relative thicknesses of the stellar disks z_0/h correlates with their face-on central surface brightnesses obtained from the 2MASS images. We also find that the scaleheight of the stellar disks shows no systematic growth with radius in most of our galaxies.