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Title: Measuring Alignments between Galaxies and the Cosmic Web at z ~ 2–3 Using IGM Tomography

Many galaxy formation models predict alignments between galaxy spin and the cosmic web (i.e., directions of filaments and sheets), leading to an intrinsic alignment between galaxies that creates a systematic error in weak-lensing measurements. These effects are often predicted to be stronger at high redshifts (z ≳ 1) that are inaccessible to massive galaxy surveys on foreseeable instrumentation, but IGM tomography of the Lyα forest from closely spaced quasars and galaxies is starting to measure the z ~ 2-3 cosmic web with requisite fidelity. Using mock surveys from hydrodynamical simulations, we examine the utility of this technique, in conjunction with coeval galaxy samples, to measure alignment between galaxies and the cosmic web at z ~ 2.5. We show that IGM tomography surveys with ≲ 5 h -1 Mpc sightline spacing can accurately recover the eigenvectors of the tidal tensor, which we use to define the directions of the cosmic web. For galaxy spins and shapes, we use a model parameterized by the alignment strength, Δ (cos θ), with respect to the tidal tensor eigenvectors from the underlying density field, and also consider observational effects such as errors in the galaxy position angle, inclination, and redshift. Measurements using the upcoming ~more » 1 deg 2 CLAMATO tomographic survey and 600 coeval zCOSMOS-Deep galaxies should place 3σ limits on extreme alignment models with Δ (cos θ) ~ 0.1, but much larger surveys encompassing > 10,000 galaxies, such as Subaru PFS, will be required to constrain models with Δ (cos θ) ~ 0.3. These measurements will constrain models of galaxy-cosmic web alignment and test tidal torque theory at z ~ 2, improving our understanding of the physics of intrinsic alignments.« less
Authors:
 [1] ; ORCiD logo [2] ;  [3] ; ORCiD logo [4]
  1. Univ. of California, Berkeley, CA (United States). Dept. of Astronomy
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States). Dept. of Physics
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  4. Univ. of California, Berkeley, CA (United States). Dept. of Astronomy; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States). Dept. of Physics
Publication Date:
Grant/Contract Number:
AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 837; Journal Issue: 1; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS
OSTI Identifier:
1436995

Krolewski, Alex, Lee, Khee-Gan, Luki?, Zarija, and White, Martin. Measuring Alignments between Galaxies and the Cosmic Web at z ~ 2–3 Using IGM Tomography. United States: N. p., Web. doi:10.3847/1538-4357/837/1/31.
Krolewski, Alex, Lee, Khee-Gan, Luki?, Zarija, & White, Martin. Measuring Alignments between Galaxies and the Cosmic Web at z ~ 2–3 Using IGM Tomography. United States. doi:10.3847/1538-4357/837/1/31.
Krolewski, Alex, Lee, Khee-Gan, Luki?, Zarija, and White, Martin. 2017. "Measuring Alignments between Galaxies and the Cosmic Web at z ~ 2–3 Using IGM Tomography". United States. doi:10.3847/1538-4357/837/1/31. https://www.osti.gov/servlets/purl/1436995.
@article{osti_1436995,
title = {Measuring Alignments between Galaxies and the Cosmic Web at z ~ 2–3 Using IGM Tomography},
author = {Krolewski, Alex and Lee, Khee-Gan and Luki?, Zarija and White, Martin},
abstractNote = {Many galaxy formation models predict alignments between galaxy spin and the cosmic web (i.e., directions of filaments and sheets), leading to an intrinsic alignment between galaxies that creates a systematic error in weak-lensing measurements. These effects are often predicted to be stronger at high redshifts (z ≳ 1) that are inaccessible to massive galaxy surveys on foreseeable instrumentation, but IGM tomography of the Lyα forest from closely spaced quasars and galaxies is starting to measure the z ~ 2-3 cosmic web with requisite fidelity. Using mock surveys from hydrodynamical simulations, we examine the utility of this technique, in conjunction with coeval galaxy samples, to measure alignment between galaxies and the cosmic web at z ~ 2.5. We show that IGM tomography surveys with ≲ 5 h-1 Mpc sightline spacing can accurately recover the eigenvectors of the tidal tensor, which we use to define the directions of the cosmic web. For galaxy spins and shapes, we use a model parameterized by the alignment strength, Δ (cos θ), with respect to the tidal tensor eigenvectors from the underlying density field, and also consider observational effects such as errors in the galaxy position angle, inclination, and redshift. Measurements using the upcoming ~ 1 deg2 CLAMATO tomographic survey and 600 coeval zCOSMOS-Deep galaxies should place 3σ limits on extreme alignment models with Δ (cos θ) ~ 0.1, but much larger surveys encompassing > 10,000 galaxies, such as Subaru PFS, will be required to constrain models with Δ (cos θ) ~ 0.3. These measurements will constrain models of galaxy-cosmic web alignment and test tidal torque theory at z ~ 2, improving our understanding of the physics of intrinsic alignments.},
doi = {10.3847/1538-4357/837/1/31},
journal = {The Astrophysical Journal (Online)},
number = 1,
volume = 837,
place = {United States},
year = {2017},
month = {2}
}