Signatures of planets in debris disks

Main sequence stars are commonly surrounded by debris disks, formed by cold far-IR-emitting dust that is thought to be continuously replenished by a reservoir of undetected dust-producing planetesimals. In a planetary system with a belt of planetesimals (like the Solar System's Kuiper Belt) and one or more interior giant planets, as the particles spiral inward due to Poynting-Robertson (P-R) drag they can get trapped in the mean motion resonances (MMRs) with the planets. This process can create structure in the dust disk, as the particles accumulate at certain semimajor axes. Sufficiently massive planets may also scatter and eject dust particles out of a planetary system, creating a dust depleted region inside the orbit of the planet, a feature that is common in most of the spatially debris disks observed so far. We have studied the efficiency of particle ejection and the resulting dust density contrast inside and outside the orbit of the planet, as a function of the planet's mass and orbital elements and the particle size. Because the debris disk structure is sensitive to long period planets, complementing a parameter space not covered by radial velocity and transit surveys, its study can help us learn about the diversity of planetary systems. Presently, the Spitzer Space Telescope is carrying out observations of debris disks most of which are spatially unresolved. It is interesting therefore to study how the structure carved by planets affects the shape of the disk's Spectral Energy Distribution (SED), and consequently if the SED can be used to infer the presence of planets. We have numerically calculated the 3-D equilibrium spatial density distributions of dust disks originated by a belt of planetesimals similar to the Kuiper Belt (KB) in the presence of interior giant planets in different planetary configurations (with planet masses ranging from 1-10 M_Jup in circular orbits with semimajor axis between 1 -30 AU). For each of these systems we calculate its SED for a representative sample of chemical compositions. We discuss what types of planetary systems can be distinguishable from one another and the main parameter degeneracies in the model SEDs. We find that the SEDs are degenerated, and therefore to unambiguously constrain the planet location we need to obtain high resolution images able to spatially resolve the disk. In the future, observatories like ALMA, LET, SAFIR, TPF and JWST will be able to image the dust in planetary systems analogous to our own.