Austrian Early Career Conference 2024

Contribution:
Talk

Authors:
Stefanie Reiter

Affiliations:
University of Vienna, Department of Astrophysics

Title:
Dynamical inference for orbit distributions of galaxies - case study of NGC 4550

Abstract:
A key aspect in studying galaxy evolution is the stellar dynamics, within which a galaxy's formation history is encoded. To disentangle the different dynamical components of observed galaxies, it is possible to construct orbit distributions from observations using orbit-based dynamical modeling. This requires the accurate extraction of the stellar kinematics from observed integrated light spectra. The most commonly used software for kinematic extraction, pPXF, results in a parametric description of the line of sight velocity distribution (LOSVD) using Gauss Hermite models. These have difficulty recovering the bimodal LOSVDs of counter-rotating galaxies, and we therefore expect as of yet unchecked biases in the dynamical inference. We test this by comparing the dynamical models of well-known counter-rotating galaxy NGC 4550 inferred from stellar kinematics extracted with pPXF to those inferred from an alternative approach using a non-parametric description of the LOSVD, Bayes-LOSVD. This talk will focus on the significant differences we find in the dynamical inference, as well as our ongoing work to address open questions concerning regularization on the orbit space.