PhD Thesis Defenses, 2017
Michael Fedderke, "Studies in Higgs physics, particle dark matter and early universe"
June 9, 2017 | 11:00 AM
Scientific Advisors: Edward W. Kolb, Lian-Tao Wang

"Michael's thesis work covers several important aspects of particle physics and cosmology. It includes detailed studies on the signal of dark matter annihilation in the galactic halo. After producing an interesting paper on the heavy particle production in the early universe, he delved into Higgs physics. He evaluated the potential of discovering new physics via fermionic Higgs portal, which has implications for the physics reach of both current and future colliders. In his most recent project, he has also constructed a model which addressed the little hierarchy problem in the composite Higgs scenario using cosmological evolution of an axion like field."
- LianTao Wang, PhD advisor

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KICP Members: Edward W. Kolb; Lian-Tao Wang
KICP Students: Michael Fedderke
Hsin-Yu Chen, "Multi-messenger Astronomy with Advanced LIGO-Virgo"
June 12, 2017 | 12:00 PM | ERC 301b
Image creadit: LIGO/Caltech/MIT/Sonoma State (Aurore Simonet)
Scientific Advisor: Daniel E. Holz

"Hsin-Yu's work is helping set the stage for the new era of gravitational-wave astronomy. She has played an active role within the LIGO collaboration in the analysis of our first detections, while also becoming a leader in the field of multi-messenger astronomy."
- Daniel E. Holz, PhD advisor

Thesis Abstract: My thesis is focused on gravitational wave multi-messenger astronomy. The most promising sources for current gravitational wave detectors are compact binary mergers, including the mergers of stellar mass binary black holes, binary neutron stars, and neutron star-black hole system. I investigated the detection rate of binary neutron star and neutron star-black hole mergers from observations of their potential electromagnetic emission. To facilitate the search for the electromagnetic counterparts and the host galaxies of compact binaries, I developed a rapid algorithm that reconstructs the sky direction and luminosity distance of binary mergers from their gravitational wave signals, and predicted the existence of well-localized events. In addition, I carried out a thorough study of how gravitational-wave observational selection effects influence electromagnetic follow-up.
In summary, I explored how to measure astrophysical and cosmological parameters with gravitational wave detections, and facilitated gravitational wave-electromagnetic follow-up through various approaches, paving the way for the future of gravitational wave astrophysics and cosmology.

Related Links:
KICP Members: Daniel E. Holz
KICP Students: Hsin-Yu Chen
Chen He Heinrich, "Lensing Bias to CMB Polarization Measurements of Compensated Isocurvature Perturbations"
June 19, 2017 | 10:30 AM | ERC 576
Scientific Advisor: Wayne Hu

Ph.D. Committee members: Daniel Holz, Abigail Vieregg, Liantao Wang.

Thesis Abstract: Compensated isocurvature perturbations (CIPs) are opposite spatial fluctuations in the baryon and dark matter (DM) densities. They arise in the curvaton model and some models of baryogenesis. While the gravitational effects of baryon fluctuations are compensated by those of DM, leaving no observable impacts on the cosmic microwave background (CMB) at first order, the baryon fluctuations correlate CMB anisotropies at different multipoles. As a result, CIPs can be reconstructed using quadratic estimators similarly to CMB detection of gravitational lensing. Because of these similarities, however, the CIP estimators are biased with lensing contributions that must be subtracted. In this work, we evaluate these lensing contributions and their impact on the CIP detection threshold due to lensing noise, and assess the prospect of detecting the maximal CIP signal in the curvaton model for a cosmic-variance-limited (CVL) temperature and polarization experiment.

Related Links:
KICP Members: Daniel E. Holz; Wayne Hu; Abigail G. Vieregg; Lian-Tao Wang
KICP Students: Chen He Heinrich