Ken Ng (Astronomy) - MIT
Title: Tracing the high-redshift binary black hole populations using the next-generation gravitational-wave detectors
Abstract: Future gravitational-wave (GW) detector networks will detect binary-black-hole mergers (BBHs) up to redshift of z~100. The extensive detector's horizon allows for probing the high-redshift BBHs in the distant universe beyond the current limit of LIGO-Virgo-Kagra. GW detections of BBHs made by proposed third-generation detectors can be used to search for the Population III (Pop III) binaries dominating at redshift z~10, as well as the primordial black holes (PBHs) binaries beyond z~30. In the first half, I will show how we can identify the Pop III BBHs by inferring the characteristic peak of the merger rate history. This is achievable by using either a model-agnostic Gaussian process regression or a parametrized phenomenological model. With one month of observations at the predicted rate of ~200 Pop III BBHs per month, parameters describing its volumetric merger rate can be constrained at the O(10%) level. In the second half, I will discuss whether a single detection of BBH at z>30 can be a direct evidence for the existence of PBHs. I will also show the preliminary results on measuring the merger rate history of these primordial BBHs.
Bio: Having Lived in Hong Kong for more than 20 years, I received my Bachelor of Science (Physics) in 2017 at the Chinese University of Hong Kong. Then, I started my graduate study in Physics at MIT, and will be finishing in 2022. I am interested in searching beyond-Standard-Model particles (e.g. axion-like particles) with gravitational waves, characterizing the effect of gravitational lensing on gravitational waves, and quantifying the measurability of the high-redshift binary black holes (either formed from the first stars or primordial relics).