Christian Vitense, Alexander V. Krivov, Hiroshi Kobayashi, Torsten Löhne
(Abridged) We access the expected EKB dust disk properties by modeling. We
treat the debiased population of the known transneptunian objects (TNOs) as
parent bodies and generate the dust with our collisional code. The resulting
dust distributions are modified to take into account the influence of
gravitational scattering and resonance trapping by planets on migrating dust
grains as well as the effect of sublimation. A difficulty is that the amount
and distribution of dust are largely determined by sub-kilometer-sized bodies.
These are directly unobservable, and their properties cannot be accessed by
collisional modeling, because objects larger than 10...60m in the present-day
EKB are not in a collisional equilibrium. To place additional constraints, we
use in-situ measurements of the New Horizons spacecraft within 20AU. We show
that the TNO population has to have a break in the size distribution at s<70km.
However, even this still leaves us with several models that all correctly
reproduce a nearly constant dust impact rates in the region of giant planet
orbits and do not violate the constraints from the non-detection of the EKB
dust thermal emission by the COBE spacecraft. The modeled EKB dust disks, which
conform to the observational constraints, can either be transport-dominated or
intermediate between the transport-dominated and collision-dominated regime.
The in-plane optical depth of such disks is tau(r>10AU)~10^-6 and their
fractional luminosity is f_d~10^-7. Planets and sublimation are found to have
little effect on dust impact fluxes and dust thermal emission. The spectral
energy distribution of an EKB analog, as would be seen from 10pc distance,
peaks at wavelengths of 40...50\mum at F~0.5mJy, which is less than 1% of the
photospheric flux at those wavelengths. Therefore, exact EKB analogs cannot be
detected with present-day instruments such as Herschel/PACS.
View original:
http://arxiv.org/abs/1202.2257
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