Halo Structural Parameters of Low Surface Brightness Galaxies

TL;DR

This study characterizes dark matter halos of low surface brightness galaxies, revealing they assemble later, have lower stellar-to-halo mass ratios, and possess higher spin parameters compared to high surface brightness galaxies.

Contribution

It provides a comprehensive analysis of LSB galaxy halo properties using multiple estimation methods and compares them with HSB galaxies, highlighting differences in assembly time, mass ratios, and angular momentum.

Findings

LSB galaxies assemble later than HSB galaxies.

LSB galaxies have up to 22% lower stellar-to-halo mass ratios.

LSB galaxies exhibit 1.2 to 2 times higher spin parameters.

Abstract

We build a volume-limited sample of galaxies derived from the SDSS-DR7 to characterize several physical properties of the dark matter halos where LSB galaxies reside. Using an observational proxy for the assembly time, we found that LSB galaxies assembly half of their total halo mass later than HSB ones, reinforcing the idea of them being unevolved systems. We use 5 different methods to estimate the total halo mass, finding that the total stellar-to-halo mass ratio is up to 22% lower in LSB galaxies. Finally, in order to estimate the spin parameter, we use a bulge+disk decomposition to obtain the specific angular momentum $j_*$ of the galaxy, a Tully-Fisher relation to estimate the rotation velocity of the disk, and the 5 different estimations of the halo mass to calculate the spin parameter. We found that the spin of LSB galaxies is 1.2 to 2 times higher than for HSB ones. We compare these results with a control sample that includes kinematic information, taken from the ALFALFA $\alpha$.100 galaxy catalog, allowing us to measure directly the rotation velocity of the disk. The trends in the values of $j_*$ and $\lambda$ are similar to the volume-limited sample.