Optical weak lensing surveys have become a powerful tool for precision cosmology, but remain subject to systematic effects that can severely bias cosmological parameter estimates if not carefully removed. We discuss the possibility of performing complementary weak lensing surveys at radio/microwave frequencies, using detections of CO-emitting galaxies with resolved continuum images from the ngVLA. This method has completely different systematic uncertainties to optical weak lensing shear measurements (e.g., in terms of blending, PSF, and redshift uncertainties), and can provide additional information to help disentangle intrinsic alignments from the cosmological shear signal. A combined analysis of optical and CO galaxy lensing surveys would therefore provide an extremely stringent validation of highly-sensitive future surveys with Euclid, LSST, and WFIRST, definitively rejecting biases due to residual systematic effects. A lensing survey on the ngVLA would also provide valuable spectral (kinematic) and polarimetric information, which can be used to develop novel cosmological analyses that are not currently possible in the optical.
Science with a Next Generation Very Large Array
- Pub Date:
- December 2018
- Astrophysics - Cosmology and Nongalactic Astrophysics
- Contribution to 2018, ASP Conference Series Monograph 7, "Science with a Next-Generation Very Large Array," Eric Murphy, ed., in preparation