Measuring Baryon Acoustic Oscillations Along the Line of Sight With Photometric Redshifts: The Pau Survey

Baryon Acoustic Oscillations (BAO) provide a “standard ruler ” of known physical length, making it one of the most promising probes of the nature of dark energy. The detection of BAO as an excess of power in the galaxy distribution at a certain scale requires measuring galaxy positions and redshifts. “Transversal ” (or “angular”) BAO measure the angular size of this scale projected in the sky and provide information about the angular distance. “Line-of-sight ” (or “radial”) BAO require very precise redshifts, but provide a direct measurement of the Hubble parameter at different redshifts, a more sensitive probe of dark energy. The main goal of this paper is to show that it is possible to obtain photometric redshifts with enough precision (σz) to measure BAO along the line of sight. There is a fundamental limitation as to how much one can improve the BAO 1