The Galaxy Progenitors of Stellar Streams around Milky Way-mass Galaxies in the FIRE Cosmological Simulations

Abstract

Stellar streams record the accretion history of their host galaxy. We present a set of simulated streams from disrupted dwarf galaxies in 13 cosmological simulations of Milky Way (MW)-mass galaxies from the FIRE-2 suite at $z=0$, including 7 isolated Milky Way-mass systems and 6 hosts resembling the MW-M31 pair (full dataset at: https://flathub.flatironinstitute.org/sapfire). In total, we identify 106 simulated stellar streams, with no significant differences in the number of streams and masses of their progenitors between the isolated and paired environments. We resolve simulated streams with stellar masses ranging from $\sim 5\times 10^5$ up to $\sim 10^9{M}_{\odot }$, similar to the mass range between the Orphan and Sagittarius streams in the MW. We confirm that present-day simulated satellite galaxies are good proxies for stellar stream progenitors, with similar properties including their stellar mass function, velocity dispersion, [Fe/H] and [$\alpha$/H] evolution tracks, and orbital distribution with respect to the galactic disk plane. Each progenitor's lifetime is marked by several important timescales: its infall, star-formation quenching, and stream-formation times. We show that the ordering of these timescales is different between progenitors with stellar masses higher and lower than $\sim 2\times 10^6{M}_{\odot }$. Finally, we show that the main factor controlling the rate of phase-mixing, and therefore fading, of tidal streams from satellite galaxies in MW-mass hosts is non-adiabatic evolution of the host potential. Other factors commonly used to predict phase-mixing timescales, such as progenitor mass and orbital circularity, show virtually no correlation with the number of dynamical times required for a stream to become phase-mixed.

26 pages, 19 figures, public dataset available at https://flathub.flatironinstitute.org/sapfire

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Cited by in corpus (12)

• Public data release of the FIRE-2 cosmological zoom-in simulations of galaxy formation
• $S^5$: The Orbital and Chemical Properties of One Dozen Stellar Streams
• The distribution of globular clusters in kinematic spaces does not trace the accretion history of the host galaxy
• Streams on FIRE: Populations of Detectable Stellar Streams in the Milky Way and FIRE
• The effects of LMC-mass environments on their dwarf satellite galaxies in the FIRE simulations
• Reading the CARDs: the Imprint of Accretion History in the Chemical Abundances of the Milky Way's Stellar Halo
• Linking the brightest stellar streams with the accretion history of Milky Way-like galaxies
• The observable properties of galaxy accretion events in Milky Way-like galaxies in the FIRE-2 cosmological simulations
• The stellar halo in Local Group Hestia simulations II. The accreted component
• The stellar halo in Local Group Hestia simulations III. Chemical abundance relations for accreted and in-situ stars
• Using Action Space Clustering to Constrain the Accretion History of Milky Way like Galaxies
• Orbital phase-driven biases in Galactic mass constraints from stellar streams