Colloq Abstract - Darling
November 15, 2019
11:00am Mountain
Jeremy Darling (U Colorado)
Real-Time Cosmology
Abstract
Ours is a dynamic universe, so most cosmological observables such as redshift, distance, or flux change over time: given enough time or enough precision, these quantities will be observed to drift. One can compensate for the short careers of astronomers by seeking high precision, but measurements of parts per billion to parts per trillion are required. Nevertheless, "real-time" cosmology is now possible with precise measurement and monitoring of the locations of objects in the sky. In an accelerating universe, cosmological redshifts of objects will drift. In an expanding universe, objects will appear to shrink as they recede, providing a geometrical distance measurement. Large-scale structures of galaxies can be observed to collapse in real time. Gravitational waves will cause distant objects to appear to move in the sky. Anisotropy or violation of the Copernican Principle will manifest as cosmic shear. The acceleration of the Sun's orbit causes distant quasars to appear to stream toward the Galactic Center. The motion of the Sun with respect to the Cosmic Microwave Background provides a means to measure the secular parallax (and thus distance) of galaxies in the local universe. The proper rotation of galaxies can be observed (the infamous van Maanen effect), providing geometric distances. I present theoretical predictions of -- and the first application of observations to -- many of these phenomena and demonstrate that we can expect to measure most of these effects within the next decade.
