WI Seminar- Andrew Long

Does the Universe contain a network of as-yet unseen topological defects?  In this talk I will discuss how current and next-generation measurements of CMB polarization may reveal a cosmic string network in the Universe today through the phenomenon of axion-induced birefringence.  We’ll discuss why axion strings are predicted to create an anisotropic birefringence signal, how this signal depends on the properties of the axion-like particle and its string network, how existing measurements of anisotropic birefringence place strong constraints on axion strings and their UV embeddings, and what are the implications for recently reported detections of isotropic cosmic birefringence.  
 

BIO:  Andrew Long is an Associate Professor of Physics and Astronomy at Rice University.  His research activities explore a range of topics in particle cosmology centered around cosmological relics: the Big Bang’s detritus that remains behind with us in the Universe today.  Specific areas of interest include the cosmological excess of matter over antimatter (and connections to primordial magnetism), the nature and origin of dark matter (solely through gravitational interactions?), and how to discover axion-like particles with a combination of experimental approaches: terrestrial (SQWARE), astrophysical (compact star), and cosmological (CMB polarization).