Title: Probing the cosmological gravitomagnetic effect via weak lensing-kSZ cross-correlations
General relativity predicts that the rotational momentum flux of matter twists the spacetime via a vector gravitomagnetic (frame-dragging) field, which so far remains undetected in cosmology. This vector field induces an additional gravitational lensing effect; at the same time, the momentum field sources the kinetic Sunyaev-Zel’dovich (kSZ) effect. The common origin of these two effects allows us to probe the gravitomagnetic signal via their cross-correlations.
In this talk, I will discuss the possibility of detecting the cosmological gravitomagnetic field by cross-correlating the weak lensing convergence field with the CMB temperature map, which is imprinted with the kSZ signal. I will show that, if the cross-correlation is measured from mock sky maps built from simulations, the numerical resolution of the latter can lead to significant contamination of the physical signal. I will then present forecasts for next-generation lensing surveys such as Euclid and LSST, and CMB experiments such as Simons Observatory and CMB Stage 4, which indicate that the cosmological gravitomagnetic effect can be detected –for the first time — provided that several foreground contaminations can be reliably removed.