2017/06/23 by Rupert A. C. Croft, Alessandro B. Romeo, Alessandro Romeo +2 · 11 citations
Physics and Astronomy · #Adaptive optics and wavefront sensing #Anisotropy #Astronomy #Astrophysics #Cosmic microwave background #Dark matter #Galaxies: Formation, Evolution, Phenomena #Galaxy #Gravitational lens #Lyman-alpha forest #Mass distribution #Optics #Photometric redshift #Physics #Quasar #Radio Astronomy Observations and Technology #Redshift #Strong gravitational lensing #Weak gravitational lensing #astro-ph.CO
paper · pdf · doi:10.1093/mnras/sty650
published in Monthly Notices of the Royal Astronomical Society 477(2), 1814-1821 (Oxford University Press) · 9 pages, 7 figures, submitted to MNRAS
arxiv created 2017/06/23 · openalex created_date 2017/06/30 · openalex publication_date 2018/03/14 · arxiv updated 2018/06/21 · openalex updated_date 2026/08/05
The angular positions of quasars are deflected by the gravitational lensing effect of foreground matter. The Lyman α (Lyα) forest seen in the spectra of these quasars is therefore also lensed. We propose that the signature of weak gravitational lensing of the Lyα forest could be measured using similar techniques that have been applied to the lensed cosmic microwave background (CMB), and which have also been proposed for application to spectral data from 21-cm radio telescopes. As with 21-cm data, the forest has the advantage of spectral information, potentially yielding many lensed ‘slices’ at different redshifts. We perform an illustrative idealized test, generating a high-resolution angular grid of quasars (of order arcminute separation), and lensing the Lyα forest spectra at redshifts z = 2–3 using a foreground density field. We find that standard quadratic estimators can be used to reconstruct images of the foreground mass distribution at z ∼ 1. There currently exists a wealth of Lyα forest data from quasar and galaxy spectral surveys, with smaller sightline separations expected in the future. Lyα forest lensing is sensitive to the foreground mass distribution at redshifts intermediate between CMB lensing and galaxy shear, and avoids the difficulties of shape measurement associated with the latter. With further refinement and application of mass reconstruction techniques, weak gravitational lensing of the high-redshift Lyα forest may become a useful new cosmological probe.