The stellar kinematics of co-rotating spiral arms in Gaia mock observations

TL;DR

This paper presents a method to generate mock Gaia observations from N-body simulations of a Milky Way-like galaxy, demonstrating that kinematic signatures of co-rotating spiral arms are detectable despite observational challenges.

Contribution

It introduces a simple sampling method to create realistic Gaia-like stellar observations from N-body models, accounting for stellar populations, dust, and Gaia's performance.

Findings

Kinematic signatures of co-rotating spiral arms are detectable in mock Gaia data.

Dust extinction and observational errors do not obscure the key kinematic features.

The method enables testing spiral arm models against Gaia observations.

Abstract

We have observed an N-body/Smoothed Particle Hydrodynamics simulation of a Milky Way like barred spiral galaxy. We present a simple method that samples N-body model particles into mock Gaia stellar observations and takes into account stellar populations, dust extinction and Gaia's science performance estimates. We examine the kinematics around a nearby spiral arm at a similar position to the Perseus arm at three lines of sight in the disc plane; (l,b)=(90,0), (120,0) and (150,0) degrees. We find that the structure of the peculiar kinematics around the co-rotating spiral arm, which is found in Kawata et al. (2014b), is still visible in the observational data expected to be produced by Gaia despite the dust extinction and expected observational errors of Gaia. These observable kinematic signatures will enable testing whether the Perseus arm of the Milky Way is similar to the co-rotating spiral arms commonly seen in N-body simulations.