Effects of Photometric Redshift Uncertainties on Weak-Lensing Tomography

By Zhaoming Ma, Wayne Hu, D. Huterer. 2005

239 citations recorded by the source corpus.

We perform a systematic analysis of the effects of photometric redshift uncertainties on weak-lensing tomography. We describe the photo-z distribution with a bias and Gaussian scatter that are allowed to vary arbitrarily between intervals of δz = 0.1 in redshift. While the mere presence of bias and scatter does not substantially degrade dark energy information, uncertainties in both parameters do. For a fiducial next-generation survey each would need to be known to better than about 0.003-0.01 in redshift for each interval in order to lead to less than a factor of 1.5 increase in the dark energy parameter errors. The more stringent requirement corresponds to a larger dark energy parameter space, when redshift variation in the equation of state of dark energy is allowed. Of order 104-105 galaxies with spectroscopic redshifts fairly sampled from the source galaxy distribution will be needed to achieve this level of calibration. If the sample is composed of multiple galaxy types, a fair sample would be required for each. These requirements increase in stringency for more ambitious surveys; we quantify such scalings with a convenient fitting formula. No single aspect of a photometrically binned selection of galaxies such as their mean or median suffices, indicating that dark energy parameter determinations are sensitive to the shape and nature of outliers in the photo-z redshift distribution.

Subfields: Astronomy and Astrophysics, Electrical and Electronic Engineering, Radiology, Nuclear Medicine and Imaging

View Paper: https://www.semanticscholar.org/paper/fd5d09b8186c8cbada13cc025f71827b1249a2a9

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Citations in the corpus

Optimal Surveys for Weak Lensing Tomography (2006, methodology): “The number of spectroscopic galaxy redshifts that are needed has also been studied by Ma et al. (2006) by assuming a 64 parameter binned bias model.”
Estimating the redshift distribution of photometric galaxy samples – II. Applications and tests of a new method (2008, background): “The power of these surveys to constrain cosmological parameters will be limited in part by the accuracy with which the galaxy redshift distributions can be deter- ⋆ mvlima@uchicago.edu mined (Huterer et al. 2004, 2006; Zhan & Knox 2006; Zhan 2006; Ma et al. 2006; Lima & Hu 2007).”
CFHTLenS tomographic weak lensing cosmological parameter constraints: Mitigating the impact of intrinsic galaxy alignments (2013, result): “This is in contrast to the conclusions of earlier cosmic-shear only optimizations, which found Nt ∼ 3 to be optimal (Simon et al. 2004; Ma et al. 2006).”
Euclid preparation (2021, background): “These ‘tails’ in the redshift distribution are important as they can significantly influence the distribution mean and provide sensitive information (Ma et al. 2006).”
Dark energy constraints from cosmic shear power spectra: impact of intrinsic alignments on photometric redshift requirements (2007, methodology): “It has been noted by several authors for the shear signal (GG) alone (e.g. Hu (1999); Simon et al. (2004); Ma et al. (2006); Amara and Refregier (2006); Jain et al. (2007)) that although a small amount of tomographic information greatly improves parameter constraints, continuing to subdivide into…”
Calibrating Redshift Distributions beyond Spectroscopic Limits with Cross-Correlations (2008, background): “The behavior of the uncertainty in recovering σz is more complex, rising rapidly (by > 5×) when the two peaks are unresolved ((z2 − z1) <∼ 1.2σz); fortunately, dark energy experiments are generally less affected by errors in σz than 〈z〉 (Ma et al. 2006).”
Simultaneous measurement of cosmology and intrinsic alignments using joint cosmic shear and galaxy number density correlations (2009, background): “This also follows fiducial Model 1 of Ma et al. (2006).”