Euclid: Early Release Observations -- Interplay between dwarf galaxies and their globular clusters in the Perseus galaxy cluster

Abstract

We present an analysis of globular clusters (GCs) of dwarf galaxies in the Perseus galaxy cluster to explore the relationship between dwarf galaxy properties and their GCs. Our focus is on GC numbers ($N_{\rm GC}$) and GC half-number radii ($R_{\rm GC}$) around dwarf galaxies, and their relations with host galaxy stellar masses ($M_*$), central surface brightnesses ($μ_0$), and effective radii ($R_{\rm e}$). Interestingly, we find that at a given stellar mass, $R_{\rm GC}$ is almost independent of the host galaxy $μ_0$ and $R_{\rm e}$, while $R_{\rm GC}/R_{\rm e}$ depends on $μ_0$ and $R_{\rm e}$; lower surface brightness and diffuse dwarf galaxies show $R_{\rm GC}/R_{\rm e}\approx 1$ while higher surface brightness and compact dwarf galaxies show $R_{\rm GC}/R_{\rm e}\approx 1.5$-$2$. This means that for dwarf galaxies of similar stellar mass, the GCs have a similar median extent; however, their distribution is different from the field stars of their host. Additionally, low surface brightness and diffuse dwarf galaxies on average have a higher $N_{\rm GC}$ than high surface brightness and compact dwarf galaxies at any given stellar mass. We also find that UDGs (ultra-diffuse galaxies) and non-UDGs have similar $R_{\rm GC}$, while UDGs have smaller $R_{\rm GC}/R_{\rm e}$ (typically less than 1) and 3-4 times higher $N_{\rm GC}$ than non-UDGs. Examining nucleated and not-nucleated dwarf galaxies, we find that for $M_*>10^8M_{\odot}$, nucleated dwarf galaxies seem to have smaller $R_{\rm GC}$ and $R_{\rm GC}/R_{\rm e}$, with no significant differences between their $N_{\rm GC}$, except at $M_*<10^8M_{\odot}$ where the nucleated dwarf galaxies tend to have a higher $N_{\rm GC}$. Lastly, we explore the stellar-to-halo mass ratio (SHMR) of dwarf galaxies and conclude that the Perseus cluster dwarf galaxies follow the expected SHMR at $z=0$ extrapolated down to $M_*=10^6M_{\odot}$.