The measurement of the expansion rate of the Universe from gamma-ray attenuation
November 6, 2014 - 10:00am
Boggs 1-90 (CRA Visualization Lab)
The extragalactic background light (EBL) that fills the Universe is mainly the result of star formation activity over cosmic time. Therefore, it contains fundamental information on galaxy evolution and cosmology. The detection of the EBL by direct methods is hampered by the strong foregrounds mainly from our own Solar System and Galaxy. Interestingly, there are other indirect methodologies that allows us its study such as observations from deep galaxy surveys and gamma-ray observations of distant sources. The latter methodology is based on the fact that very high energy photons traveling across cosmological distances interact by pair production with EBL photons producing an energy-dependent attenuation of the emitted flux. Knowledge of the EBL is thus fundamental in order to correctly interpret extragalactic observations from Cherenkov telescopes such as HAWC and the future CTA. A summary of our EBL knowledge and current and future lines of work will I will also discuss how the recent progress in the EBL understanding has allowed us to measure the expansion rate of the Universe using multiwavelength observations of blazars, which include Fermi and Cherenkov observations.