PreprintCC BY 4.0HAL
Intrinsic Tidal Shear at the Largest Scales: Galaxy Multiplet Alignment in DESI DR2
Abstract
We measure the intrinsic alignment (IA) of galaxy multiplets with the large-scale tidal field traced by galaxy positions in DESI Data Release 2. Using the BGS, LRG, and ELG samples spanning 0.01 < z < 1.6, we optimize the scales which define multiplets in each sample to minimize measurement noise. We measure multiplet tidal alignment ℰ+ on scales beyond 100 h−1Mpc in all samples, and detect alignment over 200 h−1Mpc, up to 4.5σ in the highest LRG redshift bin. We additionally present the multiplet shape-shape autocorrelation, ℰ++, which is independent of galaxy bias and provides a consistency check of our NLA (nonlinear alignment) model. We do not detect a baryon acoustic feature in the projected estimator. We also find the alignment strength of multiplets is correlated with redshift and galaxy morphology. Multiplet alignment offers direct access to the tidal shear field in all galaxy samples, even where individual galaxy alignment cannot, and extends IA detection to the largest scales yet probed.
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BibTeX
@misc{lamman2026intrinsic,
title = {{Intrinsic Tidal Shear at the Largest Scales: Galaxy Multiplet Alignment in DESI DR2}},
author = {Claire Lamman and Jessica Nicole Aguilar and Steven Ahlen and Alejandro Aviles and Davide Bianchi and David Brooks and Aurelio Carnero Rosell and Francisco Javier Castander and Todd Claybaugh and Axel de la Macorra and Daniel Eisenstein and Andreu Font-Ribera and Jaime E Forero-Romero and Cristhian Garcia-Quintero and Enrique Gaztañaga and Gaston Gutierrez and Klaus Honscheid and Mustapha Ishak and Stephanie Juneau and Tanveer Karim and David Kirkby and Ofer Lahav and Martin Landriau and Michael E Levi and Marc Manera and Aaron Meisner and Ramon Miquel and Seshadri Nadathur and Hernan Enrique Noriega and Nathalie Palanque-Delabrouille and Will Percival and Miguel Perdomo and Francisco Prada and Ignasi Pérez-Ràfols and Corentin Ravoux and Ashley J Ross and Graziano Rossi and Rossana Ruggeri and Lado Samushia and Eusebio Sanchez and Christoph Saulder and David Schlegel and Michael Schubnell and Joseph Harry Silber and Małgorzata Siudek and Gregory Tarlé and Rajeev Vaisakh and Benjamin Alan Weaver},
howpublished = {HAL},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.21839},
eprint = {2609.21839},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05763157v1},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Intrinsic Tidal Shear at the Largest Scales: Galaxy Multiplet Alignment in DESI DR2
AU - Claire Lamman
AU - Jessica Nicole Aguilar
AU - Steven Ahlen
AU - Alejandro Aviles
AU - Davide Bianchi
AU - David Brooks
AU - Aurelio Carnero Rosell
AU - Francisco Javier Castander
AU - Todd Claybaugh
AU - Axel de la Macorra
AU - Daniel Eisenstein
AU - Andreu Font-Ribera
AU - Jaime E Forero-Romero
AU - Cristhian Garcia-Quintero
AU - Enrique Gaztañaga
AU - Gaston Gutierrez
AU - Klaus Honscheid
AU - Mustapha Ishak
AU - Stephanie Juneau
AU - Tanveer Karim
AU - David Kirkby
AU - Ofer Lahav
AU - Martin Landriau
AU - Michael E Levi
AU - Marc Manera
AU - Aaron Meisner
AU - Ramon Miquel
AU - Seshadri Nadathur
AU - Hernan Enrique Noriega
AU - Nathalie Palanque-Delabrouille
AU - Will Percival
AU - Miguel Perdomo
AU - Francisco Prada
AU - Ignasi Pérez-Ràfols
AU - Corentin Ravoux
AU - Ashley J Ross
AU - Graziano Rossi
AU - Rossana Ruggeri
AU - Lado Samushia
AU - Eusebio Sanchez
AU - Christoph Saulder
AU - David Schlegel
AU - Michael Schubnell
AU - Joseph Harry Silber
AU - Małgorzata Siudek
AU - Gregory Tarlé
AU - Rajeev Vaisakh
AU - Benjamin Alan Weaver
PY - 2026
DA - 2026/09/18
PB - HAL
DO - 10.48550/arxiv.2609.21839
UR - https://hal.science/hal-05763157v1
AB - We measure the intrinsic alignment (IA) of galaxy multiplets with the large-scale tidal field traced by galaxy positions in DESI Data Release 2. Using the BGS, LRG, and ELG samples spanning 0.01 < z < 1.6, we optimize the scales which define multiplets in each sample to minimize measurement noise. We measure multiplet tidal alignment ℰ_+ on scales beyond 100 h^−1Mpc in all samples, and detect alignment over 200 h^−1Mpc, up to 4.5σ in the highest LRG redshift bin. We additionally present the multiplet shape-shape autocorrelation, ℰ_++, which is independent of galaxy bias and provides a consistency check of our NLA (nonlinear alignment) model. We do not detect a baryon acoustic feature in the projected estimator. We also find the alignment strength of multiplets is correlated with redshift and galaxy morphology. Multiplet alignment offers direct access to the tidal shear field in all galaxy samples, even where individual galaxy alignment cannot, and extends IA detection to the largest scales yet probed.
ER -