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Multiband Polarimetric Imaging of Debris Disks with the Gemini Planet Imager

  • Author(s): Arriaga, Pauline L
  • Advisor(s): Fitzgerald, Michael P
  • et al.
Abstract

High-contrast imaging techniques have enhanced our capabilities in studying

the formation and evolution of exo-solar disks and planets. In my

research, I have studied the instrumentation, data reduction, and data

analysis involved in this area. Many high-contrast imagers operate in the near-infrared

wavelengths, the systems of which are rapidly developing with new

technology. To this end, I have characterized the infrared detector of

the upgraded Keck OSIRIS imager as well as explored methods for

blocking out infrared radiation from the telescope components which

pollute the desired scientific signal. Moving downstream from the data

collection, I improved data reduction methods for suppressing the

stellar signal from high-contrast images of disks and planets, as well

as writing publically available code to forward model biases

introduced from these subtraction methods. I generalized the code for

these methods such that they can be used for most high-contrast

imaging instruments, and optimized it for disks such that it

ran two order of magnitudes faster than code optimized for planet

detection. I studied the efficacy of

my forward modeling module in further efforts to make the code more generally

used by the scientific community. I used these techniques to study the

debris disk HR4796A using multi-wavelength integral field polarimetric data form the

Gemini Planet Imager (GPI). HR4796A hosts a well-studied debris disk with a long history due to

its high fractional luminosity and favorable inclination lending

itself well to both unresolved and resolved observations.

We modelled a purely geometric disk in order to extract geometry

parameters, polarized fraction and total intensity scattering phase

functions for these data. We find that conventional methods that are

used to model debris disks cannot produce a satisfactory model of the

phase functions of the disk, indicating the need for more

sophisticated grain models.

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