Disc galaxy modelling with a particle-by-particle M2M method

TL;DR

This paper introduces a novel particle-by-particle made-to-measure (M2M) method for modeling galactic discs, demonstrating its ability to accurately reproduce target systems and adapt to incomplete data sets.

Contribution

The paper presents the first implementation of a particle-by-particle M2M method that adjusts gravitational potential and particle weights to model galactic discs from survey data.

Findings

Successfully reproduces target disc properties with no observable error.

Can adapt to incomplete data sets and still produce reasonable models.

Demonstrates the importance of parameter calibration and regularization.

Abstract

We have developed the initial version of a new particle-by-particle adaptation of the made-to-measure (M2M) method, aiming to model the Galactic disc from upcoming Galactic stellar survey data. In our new particle-by-particle M2M, the observables of the target system are compared with those of the model galaxy at the position of the target stars (i.e. particles). The weights of the model particles are changed to reproduce the observables of the target system, and the gravitational potential is automatically adjusted by the changing weights of the particles. This paper demonstrates, as the initial work, that the particle-by-particle M2M can recreate a target disc system created by an N-body simulation in a known dark matter potential, with no error in the observables. The radial profiles of the surface density, velocity dispersion in the radial and perpendicular directions, and the rotational velocity of the target disc are all well reproduced from the initial disc model, whose scale length is different from that of the target disc. We also demonstrate that our M2M can be applied to an incomplete data set and recreate the target disc reasonably well when the observables are restricted to a part of the disc. We discuss our calibration of the model parameters and the importance of regularization.