Astronomy and Astrophysics – Astrophysics
Scientific paper
2007-12-10
Astrophys.J.682:39-48,2008
Astronomy and Astrophysics
Astrophysics
9 pages 4 figures, minor changes, match the published version
Scientific paper
10.1086/588214
Weak gravitational lensing surveys using photometric redshifts can have their cosmological constraints severely degraded by errors in the photo-z scale. We explore the cosmological degradation vs the size of the spectroscopic survey required to calibrate the photo-z probability distribution. Previous work has assumed a simple Gaussian distribution of photo-z errors; here we describe a method for constraining an arbitrary parametric photo-z error model. As an example we allow the photo-z probability distribution to be the sum of $N_g$ Gaussians. To limit cosmological degradation to a fixed level, photo-z models with multiple Gaussians require up to 5 times larger calibration sample than one would estimate from assuming a single-Gaussian model. This degradation saturates at $N_g\approx 4$. Assuming a single Gaussian when the photo-z distribution has multiple parameters underestimates cosmological parameter uncertainties by up to 35%. The size of required calibration sample also depends upon the shape of the fiducial distribution, even when the RMS photo-z error is held fixed. The required calibration sample size varies up to a factor of 40 among the fiducial models studied, but this is reduced to a factor of a few if the photo-z parameters are forced to be slowly varying with redshift. Finally we show that the size of the required calibration sample can be substantially reduced by optimizing its redshift distribution. We hope this study will help stimulate work on better understanding of photo-z errors.
Bernstein Gary
Ma Zhaoming
No associations
LandOfFree
Size of spectroscopic calibration samples for cosmic shear photometric redshifts does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Size of spectroscopic calibration samples for cosmic shear photometric redshifts, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Size of spectroscopic calibration samples for cosmic shear photometric redshifts will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-405852