Measuring the scale dependence of intrinsic alignments usingmultiple shear estimates
Abstract
We present a new method for measuring the scale dependence of the intrinsic alignment (IA) contamination to the galaxy-galaxy lensing signal, which takes advantage of multiple shear estimation methods applied to the same source galaxy sample. By exploiting the resulting correlation of both shape noise and cosmic variance, our method can provide an increase in the signal-to-noise of the measured IA signal as compared to methods which rely on the difference of the lensing signal from multiple photometric redshift bins. For a galaxy-galaxy lensing measurement which uses LSST sources and DESI lenses, the signal-to-noise on the IA signal from our method is predicted to improve by a factor of ∼2 relative to the method of Blazek et al. (2012), for pairs of shear estimates which yield substantially different measured IA amplitudes and highly correlated shape noise terms. We show that statistical error necessarily dominates the measurement of IAs using our method. We also consider a physically motivated extension of the Blazek et al. (2012) method which assumes that all nearby galaxy pairs, rather than only excess pairs, are subject to IA. In this case, the signal-to-noise of the method of Blazek et al. (2012) is improved.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- September 2018
- DOI:
- 10.1093/mnras/sty1444
- arXiv:
- arXiv:1802.08263
- Bibcode:
- 2018MNRAS.479.1412L
- Keywords:
-
- gravitational lensing: weak;
- methods: data analysis;
- large-scale structure of Universe;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 16 pages, 4 figures. Accepted for publication in MNRAS