Characterizing Cosmic Acceleration with the Dark Energy Spectroscopic Instrument

Professor Adam Myers
Department of Physics and Astronomy, University of Wyoming

The nature of dark energy, the mysterious negative pressure that drives cosmic acceleration, remains one of the greatest enigmas of modern physics. The Dark Energy Spectroscopic Instrument (DESI) is a robotic multi-object spectrograph mounted on the Mayall 4-meter telescope, which can obtain spectra of ~5000 objects over ~3 degrees of the sky in a single exposure. DESI is almost halfway through a five-year survey of approximately 50 million total extragalactic and Galactic targets, which will produce precise new constraints on the expansion history of the Universe. In this talk, I will give an overview of current observational constraints on dark energy from large spectroscopic sky surveys, and how DESI will improve these constraints. In particular, I will outline how the Baryon Acoustic Oscillation (BAO) method can be used to characterize the acceleration of the Universe via measurements of the distance-redshift relation across a broad swathe of cosmic time.