Uncovering fossils of the distant Milky Way with UNIONS: NGC 5466 and its stellar stream

Abstract

We examine the spatial clustering of blue horizontal branch (BHB) stars from the $\text{u}$-band of the Canada-France Imaging Survey (CFIS, a component of the Ultraviolet Near-Infrared Optical Northern Survey, or UNIONS). All major groupings of stars are associated with previously known satellites, and among these is NGC 5466, a distant (16 kpc) globular cluster. NGC 5466 reportedly possesses a long stellar stream, although no individual members of the stream have previously been identified. Using both BHBs and more numerous red giant branch stars cross-matched to $\text{Gaia}$ Data Release 2, we identify extended tidal tails from NGC 5466 that are both spatially and kinematically coherent. Interestingly, we find that this stream does not follow the same path as the previous detection at large distances from the cluster. We trace the stream across 31${}^{\circ }$ of sky and show that it exhibits a very strong distance gradient ranging from 10 $<$ R${}_{helio}$ $<$ 30 kpc. We compare our observations to simple dynamical models of the stream and find that they are able to broadly reproduce the overall path and kinematics. The fact that NGC 5466 is so distant, traces a wide range of Galactic distances, has an identified progenitor, and appears to have recently had an interaction with the Galaxy's disk, makes it a unique test-case for dynamical modelling of the Milky Way.

References in corpus (62)

• The Sloan Digital Sky Survey: Technical Summary
• Gaia Data Release 2. Summary of the contents and survey properties
• The Structure of Cold Dark Matter Halos
• The Gaia mission
• Gaia Data Release 2: The astrometric solution
• Local Kinematics and the Local Standard of Rest
• galpy: A Python Library for Galactic Dynamics
• The Milky Way Tomography with SDSS: I. Stellar Number Density Distribution
• The merger that led to the formation of the Milky Way's inner stellar halo and thick disk
• SparsePak: A Formatted Fiber Field Unit for The WIYN Telescope Bench Spectrograph. I. Design, Construction, and Calibration
• A 2MASS All-Sky View of the Sagittarius Dwarf Galaxy: I. Morphology of the Sagittarius Core and Tidal Arms
• Euclid Definition Study Report
• The First Data Release (DR1) of the LAMOST general survey
• A geometric distance measurement to the Galactic Center black hole with 0.3% uncertainty
• The Pan-STARRS1 Surveys
• Great Circle tidal streams: evidence for a nearly spherical massive dark halo around the Milky Way
• Mean proper motions, space orbits and velocity dispersion profiles of Galactic globular clusters derived from Gaia DR2 data
• Tracing Galaxy Formation with Stellar Halos II: Relating Substructure in Phase- and Abundance-Space to Accretion Histories
• The Circular Velocity Curve of the Milky Way from $5$ to $25$ kpc
• The Milky Way total mass profile as inferred from Gaia DR2
• The Milky Way stellar halo out to 40 kpc : Squashed, broken but smooth
• Fossil Signatures of Ancient Accretion Events in the Halo
• The origin of accreted stellar halo populations in the Milky Way using APOGEE, $\text{Gaia}$, and the EAGLE simulations
• Four New Stellar Debris Streams in the Galactic Halo
• There's no place like home? Statistics of Milky Way-mass dark matter halos
• Globular Cluster Streams as Galactic High-Precision Scales - The Poster Child Palomar 5
• Ghostly Tributaries to the Milky Way: Charting the Halo's Stellar Streams with the Gaia DR2 catalogue
• The large-scale structure of the halo of the Andromeda galaxy II. Hierarchical structure in the Pan-Andromeda Archaeological Survey
• The Discovery of Tidal Tails Around NGC 5466
• The Streams of the Gaping Abyss: A population of entangled stellar streams surrounding the Inner Galaxy
• Charting the Galactic acceleration field I. A search for stellar streams with Gaia DR2 and EDR3 with follow-up from ESPaDOnS and UVES
• Detection of a 45 Degree Tidal Stream Associated with the Globular Cluster NGC 5466
• Constraining the Milky Way Halo Potential with the GD-1 stellar stream
• STREAMFINDER I: A New Algorithm for detecting Stellar Streams
• A box full of chocolates: The rich structure of the nearby stellar halo revealed by Gaia and RAVE
• Generation of mock tidal streams
• Stellar Streams and Clouds in the Galactic Halo
• The Canada-France Imaging Survey: First results from the u-band component
• The Euclid mission design
• The information content in cold stellar streams
• Fourteen candidate RR Lyrae star streams in the inner Galaxy
• Tidal Stream Morphology as an Indicator of Dark Matter Halo Geometry: the Case of Palomar 5
• The eye of Gaia on globular clusters structure: tidal tails
• Sub-structure of the outer Galactic Halo from the 2 Micron All Sky Survey
• Kinematics and Metallicities in the Bootes III Stellar Overdensity: a Disrupted Dwarf Galaxy?
• Tidal radii and destruction rates of globular clusters in the Milky Way due to bulge-bar and disk shocking
• Stellar streams as gravitational experiments II. Asymmetric tails of globular cluster streams
• A-type stars in the Canada-France Imaging Survey I. The stellar halo of the Milky Way traced to large radius by blue horizontal branch stars
• Identifying Stellar Streams in Gaia DR2 with Data Mining Techniques
• Stellar streams as gravitational experiments I. The case of Sagittarius
• Pan-STARRS1: Galaxy Clustering in the Small Area Survey 2
• The Tidal Tails of NGC 5466
• Chasing Accreted Structures within Gaia DR2 using Deep Learning
• NGC 5466: a unique probe of the Galactic halo shape
• Exploring the outskirts of globular clusters: the peculiar kinematics of NGC 3201
• Search for Extra-Tidal RR Lyrae Stars in Milky Way Globular Clusters From Gaia DR2
• Chemical abundances in the globular clusters NGC 5024 and NGC 5466 from optical and infrared spectroscopy
• Bootes III is a disrupting dwarf galaxy associated with the Styx stellar stream
• The hidden past of M92: Detection and characterization of a newly formed 17° long stellar stream using the Canada-France Imaging Survey
• Chemical Mapping of the Milky Way With The Canada-France Imaging Survey: A Non-parametric Metallicity-Distance Decomposition of the Galaxy
• The Hierarchical Structure of Galactic Haloes: Classification and characterisation with Halo-OPTICS
• Stellar Abundances in Dwarf Irregular Galaxies

Cited by in corpus (9)

• The Global Dynamical Atlas of the Milky Way mergers: Constraints from Gaia EDR3 based orbits of globular clusters, stellar streams and satellite galaxies
• galstreams: A Library of Milky Way Stellar Stream Footprints and Tracks
• Discovery of a new Local Group Dwarf Galaxy Candidate in UNIONS: Boötes V
• The e-TidalGCs Project: Modeling the extra-tidal features generated by Galactic globular clusters
• The oblateness of the Milky Way dark matter halo from the stellar streams of NGC 3201, M68, and Palomar 5
• ShapePipe: A modular weak-lensing processing and analysis pipeline
• Stellar streams and dark substructure: the diffusion regime
• A Pristine-UNIONS view on the Galaxy: Kinematics of the distant spur feature of the Sagittarius stream traced by Blue Horizontal Branch stars
• Revisit NGC 5466 Tidal Stream with $Gaia$, SDSS/SEGUE and LAMOST