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Title: Dark Energy Survey Year 1 Results: Constraints on Intrinsic Alignments and their Colour Dependence from Galaxy Clustering and Weak Lensing

Abstract

We perform a joint analysis of intrinsic alignments and cosmology using tomographic weak lensing, galaxy clustering and galaxy-galaxy lensing measurements from Year 1 (Y1) of the Dark Energy Survey. We define early- and late-type subsamples, which are found to pass a series of systematics tests, including for spurious photometric redshift error and point spread function correlations. We analyse these split data alongside the fiducial mixed Y1 sample using a range of intrinsic alignment models. In a fiducial Nonlinear Alignment Model (NLA) analysis, assuming a flat \lcdm~cosmology, we find a significant difference in intrinsic alignment amplitude, with early-type galaxies favouring $$A_\mathrm{IA} = 2.38^{+0.32}_{-0.31}$$ and late-type galaxies consistent with no intrinsic alignments at $$0.05^{+0.10}_{-0.09}$$. We find weak evidence of a diminishing alignment amplitude at higher redshifts in the early-type sample. The analysis is repeated using a number of extended model spaces, including a physically motivated model that includes both tidal torquing and tidal alignment mechanisms. In multiprobe likelihood chains in which cosmology, intrinsic alignments in both galaxy samples and all other relevant systematics are varied simultaneously, we find the tidal alignment and tidal torquing parts of the intrinsic alignment signal have amplitudes $$A_1 = 2.66 ^{+0.67}_{-0.66}$$, $$A_2=-2.94^{+1.94}_{-1.83}$$, respectively, for early-type galaxies and $$A_1 = 0.62 ^{+0.41}_{-0.41}$$, $$A_2 = -2.26^{+1.30}_{-1.16}$$ for late-type galaxies. In the full (mixed) Y1 sample the best constraints are $$A_1 = 0.70 ^{+0.41}_{-0.38}$$, $$A_2 = -1.36 ^{+1.08}_{-1.41}$$. For all galaxy splits and IA models considered, we report cosmological parameter constraints that are consistent with the results of Troxel et al. (2017) and Dark Energy Survey Collaboration (2017).

Authors:
;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL), Upton, NY (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Contributing Org.:
DES
OSTI Identifier:
1488589
Report Number(s):
arXiv:1811.06989; FERMILAB-PUB-18-622-AE
Journal ID: ISSN 0035--8711; 1704221
DOE Contract Number:  
AC02-07CH11359
Resource Type:
Journal Article
Journal Name:
Mon.Not.Roy.Astron.Soc.
Additional Journal Information:
Journal Volume: 475; Journal Issue: 4; Journal ID: ISSN 0035--8711
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS

Citation Formats

Samuroff, S., and et al. Dark Energy Survey Year 1 Results: Constraints on Intrinsic Alignments and their Colour Dependence from Galaxy Clustering and Weak Lensing. United States: N. p., 2018. Web. doi:10.1093/mnras/stx3282.
Samuroff, S., & et al. Dark Energy Survey Year 1 Results: Constraints on Intrinsic Alignments and their Colour Dependence from Galaxy Clustering and Weak Lensing. United States. doi:10.1093/mnras/stx3282.
Samuroff, S., and et al. Fri . "Dark Energy Survey Year 1 Results: Constraints on Intrinsic Alignments and their Colour Dependence from Galaxy Clustering and Weak Lensing". United States. doi:10.1093/mnras/stx3282. https://www.osti.gov/servlets/purl/1488589.
@article{osti_1488589,
title = {Dark Energy Survey Year 1 Results: Constraints on Intrinsic Alignments and their Colour Dependence from Galaxy Clustering and Weak Lensing},
author = {Samuroff, S. and et al.},
abstractNote = {We perform a joint analysis of intrinsic alignments and cosmology using tomographic weak lensing, galaxy clustering and galaxy-galaxy lensing measurements from Year 1 (Y1) of the Dark Energy Survey. We define early- and late-type subsamples, which are found to pass a series of systematics tests, including for spurious photometric redshift error and point spread function correlations. We analyse these split data alongside the fiducial mixed Y1 sample using a range of intrinsic alignment models. In a fiducial Nonlinear Alignment Model (NLA) analysis, assuming a flat \lcdm~cosmology, we find a significant difference in intrinsic alignment amplitude, with early-type galaxies favouring $A_\mathrm{IA} = 2.38^{+0.32}_{-0.31}$ and late-type galaxies consistent with no intrinsic alignments at $0.05^{+0.10}_{-0.09}$. We find weak evidence of a diminishing alignment amplitude at higher redshifts in the early-type sample. The analysis is repeated using a number of extended model spaces, including a physically motivated model that includes both tidal torquing and tidal alignment mechanisms. In multiprobe likelihood chains in which cosmology, intrinsic alignments in both galaxy samples and all other relevant systematics are varied simultaneously, we find the tidal alignment and tidal torquing parts of the intrinsic alignment signal have amplitudes $A_1 = 2.66 ^{+0.67}_{-0.66}$, $A_2=-2.94^{+1.94}_{-1.83}$, respectively, for early-type galaxies and $A_1 = 0.62 ^{+0.41}_{-0.41}$, $A_2 = -2.26^{+1.30}_{-1.16}$ for late-type galaxies. In the full (mixed) Y1 sample the best constraints are $A_1 = 0.70 ^{+0.41}_{-0.38}$, $A_2 = -1.36 ^{+1.08}_{-1.41}$. For all galaxy splits and IA models considered, we report cosmological parameter constraints that are consistent with the results of Troxel et al. (2017) and Dark Energy Survey Collaboration (2017).},
doi = {10.1093/mnras/stx3282},
journal = {Mon.Not.Roy.Astron.Soc.},
issn = {0035--8711},
number = 4,
volume = 475,
place = {United States},
year = {2018},
month = {11}
}