Probability of forming gaps in the GD-1 stream by close encounters of globular clusters

Abstract

One of the most intriguing properties of the GD-1 stellar stream is the existence of three gaps. If these gaps were formed by close encounters with dark matter subhalos, the GD-1 stream opens an exciting window through which we can see the size, mass, and velocity distributions of the dark matter subhalos in the Milky Way. However, in order to use the GD-1 stream as a probe of the dark matter substructure, we need to disprove that these gaps are not due to the perturbations from baryonic components of the Milky Way. Here we ran a large number of test particle simulations to investigate the probability that each of the known globular clusters (GCs) can form a GD-1-like gap, by using the kinematical data of the GD-1 stream and GCs from Gaia EDR3 and by fully taking into account the observational uncertainty. We found that the probability that all of the three gaps were formed by GCs is as low as $1.7\times 10^{-5}$ and the expected number of gaps formed by GCs is only $0.057$ in our fiducial model. Our result highly disfavors a scenario in which GCs form the gaps. Given that other baryonic perturbers (e.g., giant molecular clouds) are even less likely to form a gap in the retrograde-moving GD-1 stream, we conclude that at least one of the gaps in the GD-1 stream was formed by dark matter subhalos if the gaps were formed by flyby perturbations.

Main text 15 pages, References 1 page, Appendix 4 pages. 9 figures. 3 tables. ApJ accepted

References in corpus (21)

• The NumPy array: a structure for efficient numerical computation
• The Gaia mission
• galpy: A Python Library for Galactic Dynamics
• The mass distribution and gravitational potential of the Milky Way
• Gaia EDR3 view on Galactic globular clusters
• Detection of a 63 Degree Cold Stellar Stream in the Sloan Digital Sky Survey
• Constraining the Galaxy's dark halo with RAVE stars
• Globular Cluster Streams as Galactic High-Precision Scales - The Poster Child Palomar 5
• The Global Dynamical Atlas of the Milky Way mergers: Constraints from Gaia EDR3 based orbits of globular clusters, stellar streams and satellite galaxies
• Measuring the Mass of the Large Magellanic Cloud with Stellar Streams Observed by $S^5$
• All-Sky Dynamical Response of the Galactic Halo to the Large Magellanic Cloud
• Forensics of Subhalo-Stream Encounters: The Three Phases of Gap Growth
• Generation of mock tidal streams
• Detection of the Milky Way reflex motion due to the Large Magellanic Cloud infall
• Gaps in globular cluster streams: giant molecular clouds can cause them too
• Dipping Our Toes in the Water: First Models of GD-1 as a Stream
• Orbital Clustering Identifies the Origins of Galactic Stellar Streams
• Probing the nature of dark matter with accreted globular cluster streams
• Detection of Strong Epicyclic Density Spikes in the GD-1 Stellar Stream. An Absence of Evidence for the Influence of Dark Matter Subhalos?
• Action-based distribution function modelling for constraining the shape of the Galactic dark matter halo
• The structure of accreted stellar streams

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• Gaps in stellar streams as a result of globular cluster fly-bys
• An analytic description of substructure-induced gravitational perturbations in stellar systems
• Segue 2 Recently Collided with the Cetus-Palca Stream: New Opportunities to Constrain Dark Matter in an Ultra-Faint Dwarf
• Epicyclic Density Variations in the Indus Stellar Stream