Cosmology with Gravitational-Wave Standard Sirens

Abstract:  Merging compact objects are useful cosmological probes because their distance is directly encoded in their gravitational waveform. Combining this distance with an independent redshift measurement, one can measure the expansion history of the universe. In this talk, I will discuss different ways of combining the gravitational-wave distance measurement with a redshift: using an electromagnetic counterpart, a catalog of galaxies, or by measuring the redshifted mass distribution. I will summarize what these...

Wide binaries as dynamical probes

Abstract: The orbits of wide binary stars are fragile and are thus sensitive probes of the dynamical history of Galactic stellar populations. The Gaia mission has recently revolutionized the wide binary field, making it straightforward to assemble large, homogenous, and pure catalogs of binaries with a well-understood selection function. I will discuss recent discoveries enabled by these data, focusing in particular on an unexpected excess population of equal-mass "twin" binaries at wide separations that...