arXiv subjects

Ken Ng

Publications and source records attributed to Ken Ng.

2 recordsLinked to original sources

arXiv2022

Inferring the Intermediate Mass Black Hole Number Density from Gravitational Wave Lensing Statistics

The population properties of intermediate mass black holes remain largely unknown, and understanding their distribution could provide a missing link in the formation of supermassive black holes and galaxies. Gravitational wave observations can help fill in the gap from stellar mass black holes to supermassive black holes. In our work, we propose a new method for probing lens populations through lensing statistics of gravitational waves, here focusing on inferring the number density of intermediate mass black holes. Using hierarchical Bayesian inference of injected lensed gravitational waves, we find that existing gravitational wave observatories at design sensitivity could either identify an injected number density of $10^6 \mathrm{Mpc}^{-3}$ or place an upper bound of $\lesssim 10^4 \mathrm{Mpc}^{-3}$ for an injected $10^3 \mathrm{Mpc}^{-3}$. More broadly, our method could be applied to probe other forms of compact matter as well.

gr-qc↗

arXiv2021

Measuring the star formation rate with gravitational waves from binary black holes

A measurement of the history of cosmic star formation is central to understand the origin and evolution of galaxies. The measurement is extremely challenging using electromagnetic radiation: significant modeling is required to convert luminosity to mass, and to properly account for dust attenuation, for example. Here we show how detections of gravitational waves from inspiraling binary black holes made by proposed third-generation detectors can be used to measure the star formation rate (SFR) of massive stars with high precision up to redshifts of ~10. Depending on the time-delay model, the predicted detection rates ranges from ~2310 to ~56,740 per month with the current measurement of local merger rate density. With 30,000 detections, parameters describing the volumetric SFR can be constrained at the few percent level, and the volumetric merger rate can be directly measured to 3% at z ~ 2. Given a parameterized SFR, the characteristic delay time between binary formation and merger can be measured to ~60%.

astro-ph.HE↗