Globular clusters in the stellar stream surrounding the Milky Way analog NGC 5907

TL;DR

This study investigates the globular clusters in NGC 5907 and its stellar stream, revealing their properties, kinematics, and implications for the galaxy's accretion history, including a new population of young clusters.

Contribution

It provides the first detailed analysis of globular clusters in NGC 5907's stellar stream, estimating their numbers, properties, and the disrupted galaxy's mass, and identifies young star cluster candidates.

Findings

Total globular clusters estimated at 154±44.

Disrupted galaxy's stellar mass similar to Sagittarius dwarf (~10^8 M_sun).

Discovery of young star cluster candidates along the stellar disk outskirts.

Abstract

We study the globular clusters (GCs) in the spiral galaxy NGC~5907 well-known for its spectacular stellar stream -- to better understand its origin. Using wide-field Subaru/Suprime-Cam $gri$ images and deep Keck/DEIMOS multi-object spectroscopy, we identify and obtain the kinematics of several GCs superimposed on the stellar stream and the galaxy disk. We estimate the total number of globular clusters in NGC 5907 to be $154\pm44$, with a specific frequency of $0.73\pm0.21$. Our analysis also reveals a significant, new population of young star cluster candidates found mostly along the outskirts of the stellar disk. Using the properties of the stream GCs, we estimate that the disrupted galaxy has a stellar mass similar to the Sagittarius dwarf galaxy accreted by the Milky Way, i.e. $\sim10^8~M_\odot$.