Gravitational Waves In Cosmological and Black Hole Spacetimes - Postdoc at National Central University

How do gravitational waves (GWs) propagate over cosmological distances? How do they travel out to infinity from deep within the near-horizon strong gravity regime of super-massive black holes (SMBHs) residing in the centers of galaxies, including our own Milky Way? These basic questions constitute a fundamental aspect of modeling the signals sought after by GW detectors. For the SMBH case, where GWs are generated by solar-mass objects orbiting near and subsequently plunging into their horizons, there is a portion of the gravitational signal that propagates inside the null cone (aka the tail). This tail portion, in turn, produces a self-force that needs to be modeled to a high degree of accuracy in order for future generation detectors like LISA, Taiji and TianQin to properly extract the underlying physical parameters of the GW signals. In 4D curved spacetimes, the tail gravitational and electromagnetic signals can usually be associated with their long wavelength modes interacting with geometric curvature; as such, finding their unequivocal signatures can itself be interpreted as a test of (classical) field theory in curved backgrounds. On the other hand, GWs journeying over cosmological distances may pick up additional properties that could potentially provide information about the intervening distribution of matter and cosmic expansion itself.

The Department of Physics at National Central University in Taoyuan, Taiwan is offering a 1+1 year postdoctoral scholar position. The postdoctoral scholar will be working closely with Associate Professor Yi-Zen Chu, a theoretical gravitational physicist, cosmologist and field theorist. Motivated by the above-mentioned physical goals, he has been exploring various methods of computing and understanding real/position-spacetime Green's functions of wave equations in cosmological and black hole geometries -- the most relevant publications have the following arXiv identifiers: 1611.00018, 1603.00151, 1504.06337, 1310.2939, 1305.6933, and 1108.1825. Most recently, he has been trying to generalize the known asymptotically flat GW memories and energy-momentum to the cosmological context.

Yi-Zen Chu is seeking a theorist who shares similar research interests. This encompasses: (1) Solution of both linear and nonlinear wave equations, including approximation methods, asymptotic analysis and effective field theory; (2) Post-Newtonian theory and/or experience with the Extreme-Mass-Ratio-Inspiral problem; (3) Cosmological perturbation theory, the study of Large Scale Structure and/or gravitational lensing; (4) World-line path integral representations of Green's functions; (5) Gravitational and non-Abelian (Yang-Mills) scattering amplitudes; (6) Testing General Relativity in cosmological and astrophysical contexts; (7) Wolfram Mathematica software package development.

Please write to Yi-Zen Chu directly (yizen [dot] chu [at] gmail [dot] com) if you are interested in this position. Do provide a statement of current research interests; a copy of your academic CV; and have 3 referees send their letters of recommendations directly to the above e-mail address or upload them to AJO. The position is intended to begin Spring 2018 (February or so), but the starting date can likely be significantly earlier. Applications will be evaluated on a rolling basis, so please initiate contact with Yi-Zen Chu as soon as possible.

The mathematics-centric version of this ad can be found here.