Cynthia Chiang

H. Cynthia Chiang is a Dicke postdoctoral fellow in the Princeton physics department, where she works with Professor William Jones's group on millimeter-wave instrumentation and data analysis for observational cosmology.  She received her Ph.D. from the California Institute of Technology in 2008 and B.S. from the University of Illinois at Urbana-Champaign in 2002.

Cynthia's research focuses on probing the history of the universe through precision measurements of the temperature and polarization anisotropies of the cosmic microwave background (CMB).  In the current concordance cosmological model, the universe experienced inflation, a period of accelerated expansion ~10-34s after the big bang. This theory provides explanations for the origin of structure and the flat geometry of the universe observed today; however, the exact nature of inflation still remains a mystery.  Furthermore, observations suggest that the energy budget of the universe is
dominated by two components, dark energy and dark matter, about which very little is understood.  Despite its success in tying together numerous data sets, the current cosmological paradigm is a perplexing one with many unresolved puzzles.

The CMB is a rich source of information about the universe at a wide variety of epochs.  Many experiments have already measured the CMB to high precision and have placed tight constraints on the standard Lambda and Cold Dark Matter (LCDM) model, but a tremendous amount of information still remains to be extracted.  In particular, CMB polarization is relatively uncharted territory in comparison to temperature, with substantial gains still to be had in signal-to-noise ratio and the subsequent mining of the data.  One of the main goals of current experiments is to test inflationary theory by searching for a small level of curl or "B-mode" in the polarization that is sourced by gravitational waves.  A detection would be compelling evidence in favor of inflation and would even reveal its energy scale, which is given by the B-mode amplitude relative to the CMB's intrinsic "E-mode" polarization.

At Princeton, Cynthia is coordinating the end-to-end integration and testing of SPIDER, a balloon-borne microwave telescope that will probe inflationary physics by measuring CMB polarization with high fidelity at angular scales greater than 0.5 degree.  SPIDER will make a 20-day long duration balloon flight from McMurdo station in December 2012, where it will map 10% of the sky that is exceptionally clean of Galactic emission.  Cynthia is also a member of the core team for the Planck satellite's High Frequency Instrument (HFI), which has been operating since August 2009, and she works on developing robust calibration and consistency tests using the flight data.

Cynthia's thesis experiment was BICEP, a ground-based millimeter-wave polarimeter that observed for three years (2006-2008) from the Amundsen-Scott South Pole Station.  BICEP was designed with the goal of minimizing instrumental systematics in order to probe the inflationary B-mode of CMB polarization at degree angular scales. Cynthia was extensively involved in the integration and characterization of BICEP, including on-site testing at the South Pole.  She developed the primary analysis pipeline for the first data release, which produced the most stringent upper limits on CMB B-mode

Selected publications:

  • D. T. O'Dea et al., Spider Optimization II: Optical, Magnetic and Foreground Effects, Astrophysical Journal, 738, 63, 2011 (arXiv:1102.0559)
  • Planck HFI Core Team, Planck early results: First assessment of the High Frequency Instrument in-flight performance, submitted to Astronomy and Astrophysics, 2011 (arXiv:1101.2039).
  • Planck HFI Core Team, Planck early results: The High Frequency Instrument data processing, submitted to Astronomy and Astrophysics, 2011 (arXiv:1101.2048).
  • H. C. Chiang et al., Measurement of CMB Polarization Power Spectra from Two Years of BICEP Data, Astrophysical Journal, 711, 1123, 2010 (arXiv:0906.1181).
  • Y. D. Takahashi et al., Characterization of the BICEP Telescope for High-Precision Cosmic Microwave Background Polarimetry, Astrophysical Journal, 711, 1141, 2010 (arXiv:0906.4069).