A Ku-Band Polarimeter for the Owens Valley Radio Observatory 40-Meter Telescope

Citation

Karkare, Kirit Sukrit (2011) A Ku-Band Polarimeter for the Owens Valley Radio Observatory 40-Meter Telescope. Senior thesis (Major), California Institute of Technology. doi:10.7907/AX7Y-QF79. https://resolver.caltech.edu/CaltechTHESIS:02132018-113613816

Abstract

Blazars are active galactic nuclei - small, extremely luminous objects at the center of galaxies powered by material accreting around a supermassive black hole - which emit relativistic jets of highly energetic plasma along our line of sight. There is no accepted model for jet composition, acceleration, and confinement; observations at different wavelengths will help us understand these emission mechanisms. Since 2007, the 40-Meter Telescope at the Owens Valley Radio Observatory has been monitoring over 1100 blazars every two days. The variability in radio light curves is likely to be correlated with gamma-rays, which we are observing with the Fermi Gamma-Ray Space Telescope.

A new Ku-band receiver for the 40-Meter Telescope is in development. It will offer increased sensitivity, MHz spectral resolution from 12-18 GHz, and calculation of Stokes I, Q, and U parameters. In this thesis, I present the design, assembly, and testing of various components in the receiver chain. I evaluate the suitability of a commercial radio frequency over optical link for use in the receiver, describe the fabrication and verification of bandpass filters and sideband separating modules, and present the design and testing of a digital back end spectrometer which uses field-programmable gate array devices.

When complete in late 2011 , the new receiver will allow the continuation of the blazar monitoring program with the addition of spectral and polarization information, which will be invaluable in understanding blazar jet emission.