OSSOS finds an Exponential Cutoff in the Size Distribution of the Cold Classical Kuiper belt

Abstract

The cold main classical Kuiper Belt consists of those non-resonant small solar system bodies with low orbital inclinations and orbital semi-major axes between 42.4 and 47.7 au. These objects likely formed \textit{in situ} and the population has experienced minimal collisional modification since formation. Using the Outer Solar System Origins Survey (OSSOS) ensemble sample and characterization, combined with constraints from deeper surveys and supported by evidence from the Minor Planet Center catalog and the Deep Ecliptic Survey, we determine the absolute magnitude $H_r$ distribution of the cold classical belt from $H_r\simeq 5$ to 12 (roughly diameters of 400 km to 20 km). We conclude that the cold population's $H_r$ distribution exhibits an exponential cutoff at large sizes. Exponential cutoffs at large sizes are not a natural outcome of pair-wise particle accretion but exponentially tapered power-law size distributions are a feature of numerical simulations of planetesimal formation via a streaming instability. Our observation of an exponential cutoff agrees with previous observational inferences that no large objects ($D\gtrsim 400$ km) exist in the cold population. We note that the asymptotic slope of the $H_r$ distribution is consistent with $\alpha \sim 0.4$ and this asymptotic slope is also found in streaming instability modelling of planetesimal formation and is thus not necessarily associated with achieving collisional equilibrium. Studies of the transneptunian region are providing the parameters that will enable future streaming-instability studies to determine the initial conditions of planetesimal formation in the $\approx$45 au region of the Sun's protoplanetary disk.

arXiv comment20 pages, 2 figures, accepted in AAS Journals

References in corpus (38)

• emcee: The MCMC Hammer
• Rapid planetesimal formation in turbulent circumstellar discs
• A Major Asymmetric Dust Trap in a Transition Disk
• Empirical Color Transformations Between SDSS Photometry and Other Photometric Systems
• The Size Distribution of Trans-Neptunian Bodies
• The Mass and Size Distribution of Planetesimals Formed by the Streaming Instability. I. The Role of Self-Gravity
• The Canada-France Ecliptic Plane Survey - Full Data Release: The orbital structure of the Kuiper belt
• The Absolute Magnitude Distribution of Kuiper Belt Objects
• Initial mass function of planetesimals formed by the streaming instability
• OSSOS. VII. 800+ trans-Neptunian objects - the complete data release
• Impact Craters on Pluto and Charon Indicate a Deficit of Small Kuiper Belt Objects
• Pencil-Beam Surveys for Faint Trans-Neptunian Objects
• Evidence for universality in the initial planetesimal mass function
• The Size Distribution of Kuiper belt objects for D> 10 km
• The solar nebula origin of (486958) Arrokoth, a primordial contact binary in the Kuiper belt
• The Mass and Size Distribution of Planetesimals Formed by the Streaming Instability. II. The Effect of the Radial Gas Pressure Gradient
• The Kuiper Belt Luminosity Function from m(R)=21 to 26
• The Geology and Geophysics of Kuiper Belt Object (486958) Arrokoth
• Demographics of Planetesimals Formed by the Streaming Instability
• The initial conditions for planet formation: Turbulence driven by hydrodynamical instabilities in disks around young stars
• A Subaru Pencil-beam Search for m_R~27 Trans-neptunian bodies
• Destruction of Binary Minor Planets During Neptune Scattering
• De-biased Populations of Kuiper Belt Objects from the Deep Ecliptic Survey
• Ensemble Properties of Comets in the Sloan Digital Sky Survey
• Pebble-driven Planet Formation around Very Low-mass Stars and Brown Dwarfs
• The Luminosity Function of the Hot and Cold Kuiper belt Populations
• A carefully characterised and tracked Trans-Neptunian survey, the size-distribution of the Plutinos and the number of Neptunian Trojans
• A Possible Divot in the Size Distribution of the Kuiper Belt's Scattering Objects
• OSSOS. VIII. The Transition Between Two Size Distribution Slopes in the Scattering Disk
• The CFEPS Kuiper Belt Survey: Strategy and Pre-survey Results
• The Canada-France Ecliptic Plane Survey (CFEPS) - High Latitude Component
• Col-OSSOS: z Band Photometry Reveals Three Distinct TNO Surface Types
• Col-OSSOS: The Colours of the Outer Solar System Origins Survey
• OSSOS II: A Sharp Transition in the Absolute Magnitude Distribution of the Kuiper Belt's Scattering Population
• A Southern Sky and Galactic Plane Survey for Bright Kuiper Belt Objects
• Crater Density Predictions for New Horizons flyby target 2014 MU69
• Collision Probabilities in the Edgeworth-Kuiper belt
• Streaming instability on different scales. I. Planetesimal mass distribution variability

Cited by in corpus (3)

• Planetesimal Initial Mass Functions following Diffusion Regulated Gravitational Collapse
• High Resolution Study of Planetesimal Formation by Gravitational Collapse of Pebble Clouds
• Close TNO Passages as a Driver of the Origin and Evolution of Ultra-Wide Kuiper Belt Binaries