Using the Simba cosmological simulations to measure the planar relation between stellar specific angular momentum, mass and effective surface brightness

TL;DR

This study uses Simba cosmological simulations to precisely characterize the planar relationship between stellar specific angular momentum, mass, and surface brightness, enabling improved galaxy mass predictions and insights into galaxy morphology formation.

Contribution

It introduces a new, accurate measurement of the planar relation among galaxy properties using Simba simulations and applies it to observational data for better mass estimation.

Findings

Galaxies form a tight plane in log(j*)-log(M*)-mu_eff space.

The relation j* ∝ M*^0.694 is confirmed with low scatter.

The method predicts stellar masses with ~0.1-0.2 dex accuracy.

Abstract

Stellar mass and specific angular momentum are two properties of a galaxy that are directly related to its formation history, and hence morphology. In this work, the tight planar relationship between stellar specific angular momentum (j*), mass (M*) and mean effective surface brightness (mu_eff) that was recently constrained using ALFALFA galaxies is measured more accurately using galaxies from the Simba cosmological simulation. The distribution of 179 Simba galaxies in log(j*)-log(M*)-mu_eff space is shown to be very tightly planar with j* proportional to M*^0.694 and the distribution of perpendicular distances between the galaxies and the plane being approximately Gaussian with rms=0.057 dex. The parameterised distribution is used with existing j* and mu_eff measurements of 3607 ALFALFA galaxies and 84 SPARC galaxies to reliably predict their published stellar masses to within ~0.1 to 0.2 dex over several decades of stellar mass. Thus, this work presents a new method of easily generating accurate galaxy stellar mass estimates for late-type galaxies and provides a new measurement of the fundamental link between galaxy morphology, mass and angular momentum.