Cosmology Seminar- Fishing for fundamental physics: Constraining the nature of dark matter and dark energy with the SPHEREx all sky survey and with astrophysical searches for evidence of axions

The Spectro-Photometer for the history of the universe, Epoch of Reionization and ices Explorer (SPHEREx) telescope launched on March 11, 2025 with the goal of providing an all-sky map of the universe in 102 spectral bands from 750-5000 nm. SPHEREx will characterize the spectral energy distribution of hundreds of millions of galaxies enabling high precision measurements of galaxy properties and redshifts providing a 3-D map of large scale structure (LSS) over the entire sky covering redshifts from z= 0-1, complementary to other LSS surveys such as EUCLID and DESI. I will describe a new redshift estimator developed for the large number of bands and give an overview of the expected science results. I will also describe a targeted search for narrow band radio emission from axions, a light dark matter candidate. Axions were predicted as a mechanism to explain the lack of CP violation in the strong force and weakly interact with photons. In particular, axions can convert to photons in the presence of a large magnetic field and could produce a narrow emission line in the direction of objects with large magnetic fields (e.g. neutron stars) with a photon energy equal to the axion mass. We have been scanning for unexpected/mysterious emission lines from nearby isolated neutron stars across the radio and mm-wave bands where the current model of axions as dark matter predicts the most likely axion mass to be.