CMB lensing and Lyα forest cross bispectrum from DESI's first-year quasar sample

Abstract

The squeezed cross-bispectrum \bispeconed\ between the gravitational lensing in the Cosmic Microwave Background and the 1D \lya\ forest power spectrum can constrain bias parameters and break degeneracies between $\ddot{I}{ƒ}_8$ and other cosmological parameters. We detect \bispeconed\ with $4.8\ddot{I}ƒ$ significance at an effective redshift $z_{\mathrm{eff}}=2.4$ using Planck PR3 lensing map and over 280,000 quasar spectra from the Dark Energy Spectroscopic Instrument's first-year data. We test our measurement against metal contamination and foregrounds such as Galactic extinction and clusters of galaxies by deprojecting the thermal Sunyaev-Zeldovich effect. We compare our results to a tree-level perturbation theory calculation and find reasonable agreement between the model and measurement.

13 pages excluding references, 8 figures