Weak Lensing Measurements from the Lyman-α Forest
Abstract
We attempt to measure the weak lensing of the Lyman-α forest by projecting a quadratic estimator of the forest-forest and quasar-forest pair correlations, built from the DESI DR1 data, onto deflection templates constructed from low-redshift galaxies and quasars from DESI and BOSS. After validating deflection templates against the ACT DR6 and Planck PR4 CMB lensing maps and testing the estimator with injected displacements we measure the lensing amplitude AL on the data. Consistent with predictions in the literature, the current generation of public data does not have sufficient signal-to-noise to measure this effect unequivocally: we find the lensing amplitude AL=0.42±0.43 from the forest auto-correlation and 0.87±0.48 from the quasar--forest cross-correlation. These two nearly independent measurements combine to AL=0.62±0.33, consistent with both the fiducial value AL=1 and with no lensing.
Related
- Forecast for the detectability of patchy hydrogen reionization in WEAVE-QSO measurements of the Lyman-α forest power spectrum at redshift z ≥ 4
- Forecast for the detectability of patchy hydrogen reionization in WEAVE-QSO measurements of the Lyman-α forest power spectrum at redshift z ≥ 4
- Improving cosmological distance measurements at high redshift using Lyman-Alpha forest BAO reconstruction
- Joint X-Ray, Kinetic Sunyaev–Zeldovich, and Weak Lensing Measurements: Toward a Consensus Picture of Efficient Gas Expulsion from Groups and Clusters
- High resolution Lyman-α forest constraints on dark matter-neutrino scattering
BibTeX
@misc{slosar2026weak,
title = {{Weak Lensing Measurements from the Lyman-$α$ Forest}},
author = {Anže Slosar},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.36949},
eprint = {2609.36949},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.36949},
}
RIS
TY - UNPB
TI - Weak Lensing Measurements from the Lyman-α Forest
AU - Anže Slosar
PY - 2026
DA - 2026/09/29
PB - arXiv
DO - 10.48550/arxiv.2609.36949
UR - https://arxiv.org/abs/2609.36949
AB - We attempt to measure the weak lensing of the Lyman-α forest by projecting a quadratic estimator of the forest-forest and quasar-forest pair correlations, built from the DESI DR1 data, onto deflection templates constructed from low-redshift galaxies and quasars from DESI and BOSS. After validating deflection templates against the ACT DR6 and Planck PR4 CMB lensing maps and testing the estimator with injected displacements we measure the lensing amplitude A_L on the data. Consistent with predictions in the literature, the current generation of public data does not have sufficient signal-to-noise to measure this effect unequivocally: we find the lensing amplitude A_L=0.42±0.43 from the forest auto-correlation and 0.87±0.48 from the quasar--forest cross-correlation. These two nearly independent measurements combine to A_L=0.62±0.33, consistent with both the fiducial value A_L=1 and with no lensing.
ER -