The PARADIGM project II: The lifetimes and quenching of satellites in Milky Way-mass haloes

Abstract

The abundance and star-formation histories of satellites of Milky Way (MW)-like galaxies are linked to their hosts' assembly histories. To explore this connection, we use the PARADIGM suite of zoom-in hydrodynamical simulations of MW-mass haloes, evolving the same initial conditions spanning various halo assembly histories with the VINTERGATAN and IllustrisTNG models. Our VINTERGATAN simulations overpredict the number of satellites compared to observations (and to IllustrisTNG) due to a higher $M_{*}$ at fixed $M_{\rm tot}$. Despite this difference, the two models show good qualitative agreement for both satellite disruption fractions and timescales, and quenching. The number of satellites rises rapidly until $z=1$ and then remains nearly constant. The fraction of satellites from each epoch that are disrupted by $z=0$ decreases steadily from nearly 100% to 0% during $4>z>0.1$. These fractions are higher for VINTERGATAN than IllustrisTNG, except for massive satellites ($M_{*}>10^{7}\,M_{\odot}$) at $z>0.5$. This difference is largely due to varying distributions of pericentric distance, orbital period and number of orbits, in turn determined by which sub(haloes) are populated with galaxies by the two models. The time between accretion and disruption also remains approximately constant over $2>z>0.3$ at $6-8$ Gyr. For surviving satellites at $z=0$, both models recover the observed trend of massive satellites quenching more recently ($<8$ Gyr ago) and within $1.5\,r_{\rm 200c}$ of the host, while low mass satellites quench earlier and often outside the host. Our results provide constraints on satellite accretion, quenching and disruption timescales, while highlighting the convergent trends from two very different galaxy formation models.