Photo-z optimization for measurements of the BAO radial direction

Understand

Baryon Acoustic Oscillations (BAO) in the radial direction offer a method to directly measure the Universe expansion history, and to set limits to space curvature when combined to the angular BAO signal.

• In addition to spectroscopic surveys, radial BAO might be measured from accurate enough photometric redshifts obtained with narrow-band filters.
• We explore the requirements for a photometric survey using Luminous Red Galaxies (LRG) to competitively measure the radial BAO signal and discuss the possible systematic errors of this approach.
• If LRG were a highly homogeneous population, we show that the photo-z accuracy would not substantially improve by increasing the number of filters beyond $\sim 10$, except for a small fraction of the sources detected at high signal-to-noise, and broad-band filters would suffice to achieve the target $\sigma_z = 0.003 (1+z)$ for measuring radial BAO.