Aurigaia: mock Gaia DR2 stellar catalogues from the Auriga cosmological simulations

TL;DR

This paper introduces mock Gaia DR2 stellar catalogues derived from high-resolution cosmological simulations of Milky Way-like galaxies, enabling detailed comparison between models and actual Gaia data for galaxy formation studies.

Contribution

The authors provide publicly available mock Gaia DR2 catalogues based on six high-resolution AURIGA simulations, using two methods to preserve phase-space distribution and include comprehensive stellar data.

Findings

Detection of a flared young stellar disc up to 15 kpc radius.

Accurate measurement of stellar halo spin out to 100 kpc using RR Lyrae stars.

The catalogues facilitate testing analysis methods and interpreting Gaia data in galaxy formation context.

Abstract

We present and analyse mock stellar catalogues that match the selection criteria and observables (including uncertainties) of the Gaia satellite data release 2 (DR2). The source are six cosmological high-resolution magneto-hydrodynamic $\Lambda$CDM zoom simulations of the formation of Milky Way analogues from the AURIGA project. Mock data are provided for stars with $V < 16$ mag, and $V < 20$ mag at $|b|>20$ degrees. The mock catalogues are made using two different methods: the public SNAPDRAGONS code, and a method based on that of Lowing et al. that preserves the phase-space distribution of the model stars. These publicly available catalogues contain 5-parameter astrometry, radial velocities, multi-band photometry, stellar parameters, dust extinction values, and uncertainties in all these quantities. In addition, we provide the gravitational potential and information on the origin of each star. By way of demonstration, we apply the mock catalogues to analyses of the young stellar disc and the stellar halo. We show that: i) the young outer stellar disc exhibits a flared distribution that is detectable in the height and vertical velocity distribution of A- and B-dwarf stars up to radii of ~15 kpc; and ii) the spin of the stellar halo out to 100 kpc can be accurately measured with Gaia DR2 RR Lyrae stars. These catalogues are well suited for comparisons with observations and should help to: i) develop and test analysis methods for the Gaia DR2 data; ii) gauge the limitations and biases of the data and iii) interpret the data in the light of theoretical predictions from realistic $ab$ $initio$ simulations of galaxy formation in the $\Lambda$CDM cosmological model.