A 10 kpc stellar substructure at the edge of the Large Magellanic Cloud: perturbed outer disk or evidence for tidal stripping?

Abstract

We report the discovery of a substantial stellar overdensity in the periphery of the Large Magellanic Cloud (LMC), found using public imaging from the first year of the Dark Energy Survey. The structure appears to emanate from the edge of the outer LMC disk at a radius $\approx 13.5$ degrees due north of its centre, and stretches more than $10$ kpc towards the east. It is roughly $1.5$ kpc wide and has an integrated $V$-band luminosity of at least $M_V=-7.4$. The stellar populations in the feature are indistinguishable from those in the outer LMC disk. We attempt to quantify the geometry of the outer disk using simple planar models, and find that only a disk with mild intrinsic ellipticity can simultaneously explain the observed stellar density on the sky and the azimuthal line-of-sight distance profile. We also see possible non-planar behaviour in the outer disk that may reflect a warp and/or flare, as well as deviations that resemble a ring-like structure between $\sim 9-12$ degrees from the LMC centre. Based on all these observations, we conclude that our remote, stream-like feature is likely comprised of material that has been stripped from the outskirts of the LMC disk, although we cannot rule out that it represents a transient overdensity in the disk itself. We conduct a simple $N$-body simulation to show that either type of structure could plausibly arise due to the tidal force of the Milky Way; however we also recognize that a recent close interaction between the LMC and the SMC may be the source of the stripping or perturbation. Finally, we observe evidence for extremely diffuse LMC populations extending to radii of $\sim 18.5$ kpc in the disk plane ($\approx 20$ degrees on the sky), corroborating previous spectroscopic detections at comparable distances.

Accepted for publication in MNRAS; this posting updated to match the accepted version

References in corpus (21)

• The Dartmouth Stellar Evolution Database
• The Dark Energy Camera
• Eight New Milky Way Companions Discovered in First-Year Dark Energy Survey Data
• Beasts of the Southern Wild: Discovery of nine Ultra Faint satellites in the vicinity of the Magellanic Clouds
• The Origin of the Magellanic Stream and Its Leading Arm
• The Blanco Cosmology Survey: Data Acquisition, Processing, Calibration, Quality Diagnostics and Data Release
• A timing constraint on the (total) mass of the Large Magellanic Cloud
• Clustering of Local Group distances: publication bias or correlated measurements? I. The Large Magellanic Cloud
• Exploring Halo Substructure with Giant Stars XI: The Tidal Tails of the Carina Dwarf Spheroidal and the Discovery of Magellanic Cloud Stars in the Carina Foreground
• Hydra II: a faint and compact Milky Way dwarf galaxy found in the Survey of the Magellanic Stellar History
• Horologium II: a Second Ultra-faint Milky Way Satellite in the Horologium Constellation
• Satellite Dwarf Galaxies in a Hierarchical Universe: The Prevalence of Dwarf-Dwarf Major Mergers
• Satellites of LMC-Mass Dwarfs: Close Friendships Ruined by Milky Way Mass Halos
• Discovery of a Faint Outer Halo Milky Way Star Cluster in the Southern Sky
• Stellar streams around the Magellanic Clouds
• A PAndAS view of M31 dwarf elliptical satellites: NGC147 and NGC185
• The LMC geometry and outer stellar populations from early DES data
• OGLE-ing the Magellanic System: Stellar populations in the Magellanic Bridge
• Sailing under the Magellanic Clouds: A DECam View of the Carina Dwarf
• Photometry of Magellanic Cloud clusters with the Advanced Camera for Surveys - II. The unique LMC cluster ESO 121-SC03
• An Improved Photometric Calibration of the Sloan Digital Sky Survey Imaging Data

Cited by in corpus (76)

• The Dark Energy Survey: more than dark energy - an overview
• The total mass of the Large Magellanic Cloud from its perturbation on the Orphan stream
• Hunting for the Dark Matter Wake Induced by the Large Magellanic Cloud
• The Magellanic Stream: Circumnavigating the Galaxy
• SMASH - Survey of the MAgellanic Stellar History
• The VMC Survey. XXV. The 3D structure of the Small Magellanic Cloud from Classical Cepheids
• Orbits of Massive Satellite Galaxies: I. A Close Look at the Large Magellanic Cloud and a New Orbital History for M33
• Snake in the Clouds: A new nearby dwarf galaxy in the Magellanic bridge
• At the survey limits: discovery of the Aquarius 2 dwarf galaxy in the VST ATLAS and the SDSS data
• The Proper Motion Field of the Small Magellanic Cloud: Kinematic Evidence for its Tidal Disruption
• Clouds, Streams and Bridges. Redrawing the blueprint of the Magellanic System with Gaia DR1
• SMASHing the LMC: A Tidally-induced Warp in the Outer LMC and a Large-scale Reddening Map
• An Ultra-Faint Galaxy Candidate Discovered in Early Data from the Magellanic Satellites Survey
• Final Targeting Strategy for the SDSS-IV APOGEE-2S Survey
• The effect of the LMC on the Milky Way system
• Hypervelocity runaways from the Large Magellanic Cloud
• The Proper Motion Field Along the Magellanic Bridge: a New Probe of the LMC-SMC Interaction
• The synchronised dance of the Magellanic Clouds' star formation history
• Revealing the tidal scars of the Small Magellanic Cloud
• Ships Passing in the Night: Spectroscopic Analysis of Two Ultra-Faint Satellites in the Constellation Carina
• Substructures and tidal distortions in the Magellanic stellar periphery
• Clouds in Arms
• The Clouds are breaking: tracing the Magellanic system with Gaia DR1 Mira variables
• SMASHing THE LMC: Mapping a Ring-like Stellar Overdensity in the LMC Disk
• The Halos and Environments of Nearby Galaxies (HERON) I: Imaging, Sample Characteristics, and Envelope Diameters
• The highest-speed local dark matter particles come from the Large Magellanic Cloud
• Exploring the Very Extended Low Surface Brightness Stellar Populations of the Large Magellanic Cloud with SMASH
• The VMC Survey -- XLVIII. Classical Cepheids unveil the 3D geometry of the LMC
• The VMC survey -- XLIV: Mapping metallicity trends in the Large Magellanic Cloud using near-infrared passbands
• Magellanic Mayhem: Metallicities and Motions
• The VMC survey -- XLI. Stellar proper motions within the Small Magellanic Cloud
• Stellar substructures in the periphery of the Magellanic Clouds with the VISTA Hemisphere Survey from the red clump and other tracers
• The period--luminosity relation for Mira variables in the Milky Way using Gaia DR3: a further distance anchor for $H_0$
• The Magellanic Edges Survey I. Description and First Results
• Discovery of a disrupting open cluster far into the Milky Way halo: a recent star formation event in the leading arm of the Magellanic stream?
• Star cluster formation history along the minor axis of the Large Magellanic Cloud
• The VISCACHA survey -- II. Structure of star clusters in the Magellanic Clouds periphery
• The VMC survey -- XXXIX: Mapping metallicity trends in the Small Magellanic Cloud using near-infrared passbands
• On the nature of a shell of young stars in the outskirts of the Small Magellanic Cloud
• The Magellanic Edges Survey III. Kinematics of the disturbed LMC outskirts
• OGLE-ing the Magellanic System: RR Lyrae Stars in the Bridge
• Tidally stripped halo stars from the Large Magellanic Cloud in the Galactic North
• A panoramic view of the Local Group dwarf galaxy NGC 6822
• Discovery of Magellanic Stellar Debris in the H3 Survey
• Young stars in the periphery of the Large Magellanic Cloud
• Stellar cluster candidates discovered in the Magellanic System
• Comparing hypervelocity star populations from the Large Magellanic Cloud and the Milky Way
• Stellar streams around the Magellanic Clouds in 4D
• Equilibrium dynamical models in the inner region of the Large Magellanic Cloud based on Gaia DR3 kinematics
• Gaia Early Data Release 3: Structure and properties of the Magellanic Clouds
• Precise Measurements of the LMC Bar's Geometry With Gaia DR3 and a Novel Solution to Crowding Induced Incompleteness in Star Counting
• No sign (yet) of intergalactic globular clusters in the Local Group
• Lessons from the Magellanic System and its modeling
• The Magellanic Puzzle: origin of the periphery
• Cold, old and metal-poor: New stellar substructures in the Milky Way's dwarf spheroidals
• Spatio-temporal map of star clusters in the Magellanic Clouds using Gaia: Synchronized peaks and radial shrinkage of cluster formation
• Astrophysical properties of newly discovered Magellanic Cloud star clusters
• A likely runaway star cluster in the outer disc of the Large Magellanic Cloud
• Response of the LMC's Bar to a Recent SMC Collision and Implications for the SMC's Dark Matter Profile
• The VMC survey -- LIV. The internal kinematics of the LMC with new VISTA observations
• The Smallest Scale of Hierarchy Survey (SSH). I. Survey Description
• Kinematical Analysis of Substructure in the Southern Periphery of the Large Magellanic Cloud
• Chemo-Dynamical Tagging in the Outskirts: The Origins of Stellar Substructures in the Magellanic Clouds
• The 3D kinematics of stellar substructures in the periphery of the Large Magellanic Cloud
• Discovery of NES, an extended tidal structure in the North-East of the Large Magellanic Cloud
• The YMCA (Yes, Magellanic Clouds Again) survey: probing the outer regions of the Magellanic system with VST
• Stellar density distribution along the minor axis of the Large Magellanic Cloud
• Strömgren photometric metallicity map of the Magellanic Cloud stars using Gaia DR3--XP spectra
• Magellanic System Stars Identified in SMACS J0723.3-7327 James Webb Space Telescope Early Release Observations Images
• The Magellanic Edges Survey -- II. Formation of the LMC's northern arm
• In-Situ Star Formation in the Outskirts of the Large Magellanic Cloud: Gaia DR2 Confirmation
• Mapping the Distorted Dark Matter Distribution of the LMC-SMC System Prior to Milky Way Infall with Basis Function Expansions
• The VMC survey -- XLVI. Stellar proper motions in the centre of the Large Magellanic Cloud
• The tidal features of the classical Milky Way satellites: Expected in MOND but inconsistent with cold dark matter models
• Structural parameters and possible association of the Ultra-Faint Dwarfs Pegasus III and Pisces II from deep Hubble Space Telescope photometry
• The orbital dynamics of the LMC and SMC about the Milky Way