Made-to-measure galaxy models - III Modelling with Milky Way observations

TL;DR

This paper adapts the made-to-measure stellar dynamical modelling method to the Milky Way's rotating bar, validating it with existing models and observations, and discusses its general applicability and potential for combining with N-body techniques.

Contribution

It introduces modifications to the made-to-measure method for rotating galactic bars and demonstrates its validation using Milky Way observations and models.

Findings

Consistent bar angle (~30°) and pattern speed (~40 km/s/kpc) with N-body models.

Validated the adapted method with BRAVA observational data.

Showed the method's general applicability to different models and data sets.

Abstract

We demonstrate how the Syer & Tremaine made-to-measure method of stellar dynamical modelling can be adapted to model a rotating galactic bar. We validate our made-to-measure changes using observations constructed from the existing Shen et al. (2010) N-body model of the Milky Way bar, together with kinematic observations of the Milky Way bulge and bar taken by the Bulge Radial Velocity Assay (BRAVA). Our results for a combined determination of the bar angle and bar pattern speed (~30 degrees and ~40 km/s/kpc) are consistent with those determined by the N-body model. Whilst the made-to-measure techniques we have developed are applied using a particular N-body model and observational data set, they are in fact general and could be applied to other Milky Way modelling scenarios utilising different N-body models and data sets. Additionally, we use the exercise as a vehicle for illustrating how N-body and made-to-measure methods might be combined into a more effective method.