AuriDESI: Mock Catalogues for the DESI Milky Way Survey

TL;DR

This paper introduces mock catalogues for the DESI Milky Way Survey, enabling testing of methods to analyze stellar halo substructures and the galaxy's accretion history using simulated data.

Contribution

It presents a novel set of mock catalogues based on high-resolution simulations, tailored to DESI MWS selection criteria, to facilitate analysis of the Milky Way's assembly history.

Findings

Mock catalogues reproduce DESI MWS selection criteria.

They include detailed stellar properties and simulation data.

Rich accretion histories with diverse substructures are modeled.

Abstract

The Dark Energy Spectroscopic Instrument Milky Way Survey (DESI MWS) will explore the assembly history of the Milky Way by characterising remnants of ancient dwarf galaxy accretion events and improving constraints on the distribution of dark matter in the outer halo. We present mock catalogues that reproduce the selection criteria of MWS and the format of the final MWS data set. These catalogues can be used to test methods for quantifying the properties of stellar halo substructure and reconstructing the Milky Way's accretion history with the MWS data, including the effects of halo-to-halo variance. The mock catalogues are based on a phase-space kernel expansion technique applied to star particles in the Auriga suite of six high-resolution $\Lambda$CDM magneto-hydrodynamic zoom-in simulations. They include photometric properties (and associated errors) used in DESI target selection and the outputs of the MWS spectral analysis pipeline (radial velocity, metallicity, surface gravity, and temperature). They also include information from the underlying simulation, such as the total gravitational potential and information on the progenitors of accreted halo stars. We discuss how the subset of halo stars observable by MWS in these simulations corresponds to their true content and properties. These mock Milky Ways have rich accretion histories, resulting in a large number of substructures that span the whole stellar halo out to large distances and have substantial overlap in the space of orbital energy and angular momentum.