Abstract:   As LIGO continues its third observing run, the added gravitational wave (GW) events provide the promise of further tests of general relativity (GR). In the future the early inspiral of a select number of stellar mass black-hole binaries, like GW150914, will be detectable at low frequencies (10-100 mHz) by the upcoming LISA space mission. Multi-band GW astronomy is a promising avenue for improved tests of GR, both in the weak-field regime and its propagation, constraints on eccentricity...

Galaxy formation simulations: "sub-grid" vs. physics

Cosmological simulations of structure formation have undergone rapid development over the last decade and evolved from purely gravitational computations of large scale structure to full hydrodynamical simulations which include a plethora of complex baryonic physics. Recent successes of these simulations have been impressive, with several independent groups obtaining models of present day galaxies with a morphological mix in broad accord with observation, which has been a long standing goal for more...