The Mass of Stirring Bodies in the AU Mic Debris Disk Inferred from Resolved Vertical Structure

Abstract

The vertical distribution of dust in debris disks is sensitive to the number and size of large planetesimals dynamically stirring the disk, and is therefore well-suited for constraining the prevalence of otherwise unobservable Uranus and Neptune analogs. Information regarding stirring bodies has previously been inferred from infrared and optical observations of debris disk vertical structure, but theoretical works predict that the small particles traced by short-wavelength observations will be `puffed up' by radiation pressure, yielding only upper limits. The large grains that dominate the disk emission at millimeter wavelengths are much less sensitive to the effects of stellar radiation or stellar winds, and therefore trace the underlying mass distribution more directly. Here we present ALMA 1.3 mm dust continuum observations of the debris disk around the nearby M star AU Mic. The 3 au spatial resolution of the observations, combined with the favorable edge-on geometry of the system, allows us to measure the vertical thickness of the disk. We report a scale height-to-radius aspect ratio of $h=0.031_{-0.004}^{+0.005}$ between radii of $\sim 23$ au and $\sim 41$ au. Comparing this aspect ratio to a theoretical model of size-dependent velocity distributions in the collisional cascade, we find that the perturbing bodies embedded in the local disk must be larger than about 400 km, and the largest perturbing body must be smaller than roughly 1.8 M${}_{\odot }$. These measurements rule out the presence of a gas giant or Neptune analog near the $\sim 40$ au outer edge of the debris ring, but are suggestive of large planetesimals or an Earth-sized planet stirring the dust distribution.

arXiv comment21 pages, 8 figures, 5 tables. Accepted for publication in ApJ

References in corpus (53)

• emcee: The MCMC Hammer
• The NumPy array: a structure for efficient numerical computation
• Gaia Data Release 2. Summary of the contents and survey properties
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• The Gaia mission
• Protoplanetary Disks and Their Evolution
• Density of asteroids
• How Observations of Circumstellar Disk Asymmetries Can Reveal Hidden Planets: Pericenter Glow and its Application to the HR 4796 Disk
• On the age of the $\beta$ Pictoris moving group
• Debris Disks: Structure, Composition, and Variability
• Weak Turbulence in the HD 163296 Protoplanetary Disk Revealed by ALMA CO Observations
• A Three-Dimensional View of Turbulence: Constraints on Turbulent Motions in the HD 163296 Protoplanetary Disk using DCO${}^{+}$
• Collisional Processes in Extrasolar Planetsimal Disks - Dust Clumps in Fomalhaut's Debris Disk
• Discovery of a large dust disk around the nearby star AU Microscopium
• A lithium depletion boundary age of 21 Myr for the Beta Pictoris moving group
• Probing for Exoplanets Hiding in Dusty Debris Disks: Disk Imaging, Characterization, and Exploration with HST/STIS Multi-Roll Coronagraphy
• Dust Migration and Morphology in Optically Thin Circumstellar Gas Disks
• A Spatially Resolved Vertical Temperature Gradient in the HD 163296 Disk
• Dust Dynamics, Surface Brightness Profiles, and Thermal Spectra of Debris Disks: The Case of AU Mic
• New Debris Disks Around Young, Low Mass Stars Discovered With The Spitzer Space Telescope
• Collisional processes and size distribution in spatially extended debris discs
• Exocometary gas in the HD 181327 debris ring
• Formation of close in Super-Earths \& Mini-Neptunes: Required Disk Masses \& Their Implications
• BANYAN. IV. Fundamental parameters of low-mass star candidates in nearby young stellar kinematic groups - Isochronal Age determination using Magnetic evolutionary models
• Exocometary gas structure, origin and physical properties around $\beta$ Pictoris through ALMA CO multi-transition observations
• Disk Radii and Grain Sizes in Herschel-Resolved Debris Disks
• A Sub-Millimeter Search of Nearby Young Stars for Cold Dust: Discovery of Debris Disks around Two Low-Mass Stars
• Millimeter Emission Structure in the first ALMA Image of the AU Mic Debris Disk
• Azimuthal asymmetries in the debris disk around HD61005
• The dust grain size - stellar luminosity trend in debris discs
• Kuiper Belt-Like Hot and Cold Populations of Planetesimal Inclinations in the $\beta$ Pictoris Belt Revealed by ALMA
• Detection of a Millimeter Flare From Proxima Centauri
• Incidence of debris discs around FGK stars in the solar neighbourhood
• Self-consistent size and velocity distributions of collisional cascades
• The AU Microscopii Debris Disk: Multiwavelength Imaging and Modeling
• Vertical structure of debris discs
• Radial Surface Density Profiles of Gas and Dust in the Debris Disk around 49 Ceti
• Adaptive Optics Imaging of the AU Microscopii Circumstellar Disk: Evidence for Dynamical Evolution
• Constraints on Planetesimal Collision Models in Debris Disks
• Observations of fast-moving features in the debris disk of AU Mic on a three-year timescale: Confirmation and new discoveries
• ALMA observations of the narrow HR 4796A debris ring
• Planetary embryos and planetesimals residing in thin debris disks
• Collisional modelling of the AU Microscopii debris disc
• The AU Mic Debris Disk: far-infrared and submillimeter resolved imaging
• Gemini Planet Imager Observations of the AU Microscopii Debris Disk: Asymmetries within One Arcsecond
• Expelled grains from an unseen parent body around AU Mic
• Very deep images of the innermost regions of the beta Pictoris debris disc at Lp
• Constraining a Model of Turbulent Coronal Heating for AU Microscopii with X-Ray, Radio, and Millimeter Observations
• Stellar Winds and Dust Avalanches in the AU Mic Debris Disk
• Simulating radio emission from Low Mass Stars
• Probing Dust Settling in Proto-planetary Disks with ALMA
• Transient events in bright debris discs: Collisional avalanches revisited
• Near-Infrared Image of the Debris Disk around HD 15115

Cited by in corpus (41)

• The Ophiuchus DIsc Survey Employing ALMA (ODISEA)-III: the evolution of substructures in massive discs at 3-5 au resolution
• Investigating the young AU~Mic system with SPIRou: large-scale stellar magnetic field and close-in planet mass
• Evidence for a high mutual inclination between the cold Jupiter and transiting super Earth orbiting $\pi$ Men
• Solution to the debris disc mass problem: planetesimals are born small?
• Planet populations inferred from debris discs: insights from 178 debris systems in the ISPY, LEECH and LIStEN planet-hunting surveys
• Transmission spectroscopy and Rossiter-McLaughlin measurements of the young Neptune orbiting AU Mic
• Insights into the planetary dynamics of HD 206893 with ALMA
• From scattered-light to millimeter emission: A comprehensive view of the Gyr-old system of HD 202628 and its eccentric debris ring
• High resolution ALMA and HST images of q${}^1$ Eri: an asymmetric debris disc with an eccentric Jupiter
• The vertical structure of debris disks and the impact of gas
• Constraining planetesimal stirring: how sharp are debris disc edges?
• Deprojecting and constraining the vertical thickness of exoKuiper belts
• ALMA Observations of the HD~110058 debris disk
• Observability of Debris Discs around M-stars
• The Geometry of the G29-38 White Dwarf Dust Disk from Radiative Transfer Modeling
• Resolving Structure in the Debris Disk around HD 206893 with ALMA
• The formation of wide exoKuiper belts from migrating dust traps
• Extrasolar Kuiper Belts
• Stirred but not shaken: a multi-wavelength view of HD 16743's debris disc
• High Fidelity Imaging of the Inner AU Mic Debris Disk: Evidence of Differential Wind Sculpting?
• Rave: A non-parametric method for recovering the surface brightness and height profiles of edge-on debris disks
• Multiwavelength Vertical Structure in the AU Mic Debris Disk: Characterizing the Collisional Cascade
• The ALMA survey to Resolve exoKuiper belt Substructures (ARKS) II. The radial structure of debris discs
• The ALMA survey to Resolve exoKuiper belt Substructures (ARKS) I: Motivation, sample, data reduction, and results overview
• Inner edges of planetesimal belts: collisionally eroded or truncated?
• Debris Disks in Multi-Planet Systems: Are Our Inferences Compromised by Unseen Planets?
• Mutual inclinations between giant planets and their debris discs in HD 113337 and HD 38529
• The big sibling of AU Mic: a cold dust-rich debris disk around CP-72 2713 in the $\beta$ Pic moving group
• The vertical structure of debris discs and the role of disc gravity: A primer using a simplified model
• Probing the innermost region of the AU~Microscopii debris disk
• High resolution ALMA and HST imaging of $\kappa$CrB: a broad debris disc around a post-main sequence star with low-mass companions
• A Mixed Stirring Mechanism for Debris Discs with Giant and Dwarf Planetary Perturbations
• The ALMA survey to Resolve exoKuiper belt Substructures (ARKS) IV: CO gas imaging and overview
• The ALMA survey to Resolve exoKuiper belt Substructures (ARKS) III: The vertical structure of debris disks
• Formation of Multiple Dynamical Classes in the Kuiper Belt via Disk Dissipation
• Collisional damping in debris discs: Only significant if collision velocities are low
• The Mysterious Affair of the H${}_2$ in AU Mic
• ALMA's view of the M-dwarf GSC 07396-00759's edge-on debris disc: AU Mic's coeval twin
• Seeking echoes of circumstellar disks in Kepler light curves
• The Disks In Scorpius-Centaurus Survey (DISCS) I: Four Newly-Resolved Debris Disks in Polarized Intensity Light
• AU Mic b is the Youngest Planet to have a Spin-Orbit Alignment Measurement