The Effect of the Angular Momentum in the Formation and Evolution of Low Surface Brightness Galaxies

TL;DR

This study compares the angular momentum of low and high surface brightness galaxies, revealing that LSBGs generally have higher spin values, especially under the biased collapse model, with implications for galaxy formation theories.

Contribution

It provides the first comprehensive comparison of angular momentum between LSBGs and HSBGs using observational data, and tests different formation models to estimate galaxy spin.

Findings

LSBGs are higher in the Fall relation by about 0.174 dex.

No clear difference in spin under the classic disk formation model.

LSBGs have approximately twice the spin of HSBGs under the biased collapse model.

Abstract

Using observed data from the literature, we compare in one single publication the angular momentum (AM) of low surface brightness galaxies (LSBGs), with that of high surface brightness galaxies (HSBGs), a comparison that either is currently spread across many unconnected references, or simply does not exist. Partly because of the subject, this has received little attention outside the realm of simulations. We use previous results of the stellar specific AM $j_{*}$ from the SPARC database containing Spitzer 3.6 $\mu$m photometry and accurate H I rotation curves from Lelli et al. using a sample of 38 LSBGs and 82 HSBGs. We do this with the objective of comparing both galaxy populations, finding that LSBGs are higher in the Fall relation by about 0.174 dex. Additionally, we apply and test different masses and formation models to estimate the spin parameter $\lambda$, which quantifies the rotation obtained from the tidal torque theory, finding no clear evidence of a difference in the spin of LSBGs and HSBGs under a classic disk formation model that assumes the ratio ($f_{j}$) between $j_{*}$ and the specific AM of the halo is $\sim 1$. In another respect, by using the biased collapse model, where $f_{j}$ depends on the star formation efficiency, it was found that LSBGs clearly show higher spin values, having an average spin of $\sim 2$ times the average spin of HSBGs. This latter result is consistent with those obtained from simulations by Dalcanton et al.