Gaia quasar proper motions show a significant quadrupole signal matching an axisymmetric Bianchi I anisotropy model, but the amplitude does not increase with redshift as the model requires and the inferred local shear exceeds expectations.
Measuring D_A and H at z=0.35 from the SDSS DR7 LRGs using baryon acoustic oscillations
3 Pith papers cite this work. Polarity classification is still indexing.
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abstract
We present measurements of the angular diameter distance D_A(z) and the Hubble parameter H(z) at z=0.35 using the anisotropy of the baryon acoustic oscillation (BAO) signal measured in the galaxy clustering distribution of the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) Luminous Red Galaxies (LRG) sample. Our work is the first to apply density-field reconstruction to an anisotropic analysis of the acoustic peak. Reconstruction partially removes the effects of non-linear evolution and redshift-space distortions in order to sharpen the acoustic signal. We present the theoretical framework behind the anisotropic BAO signal and give a detailed account of the fitting model we use to extract this signal from the data. Our method focuses only on the acoustic peak anisotropy, rather than the more model-dependent anisotropic information from the broadband power. We test the robustness of our analysis methods on 160 LasDamas DR7 mock catalogues and find that our models are unbiased at the ~0.2% level in measuring the BAO anisotropy. After reconstruction we measure D_A(z=0.35)=1050+/-38 Mpc and H(z=0.35)=84.4+/-7.0 km/s/Mpc assuming a sound horizon of r_s=152.76 Mpc. Note that these measurements are correlated with a correlation coefficient of 0.58. This represents a factor of 1.4 improvement in the error on D_A relative to the pre-reconstruction case; a factor of 1.2 improvement is seen for H.
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Mapping the Universe as a Bianchi I cosmology with Gaia data
Gaia quasar proper motions show a significant quadrupole signal matching an axisymmetric Bianchi I anisotropy model, but the amplitude does not increase with redshift as the model requires and the inferred local shear exceeds expectations.
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Impact of fiducial cosmology in model-agnostic cosmological inference with the BAO feature
The Zel'dovich smearing approximation for model-agnostic BAO inference is extended to include fiducial cosmology distortions and validated on AbacusSummit simulations of DESI- and Euclid-like samples, producing unbiased constraints.
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Full Nonlinear Velocity Reconstruction With Transformer and Ensemble Tree Machine Learning
Transformer and GBDT models trained on AbacusSummit mocks for DESI LRGs/ELGs recover nonlinear velocity power spectra and cross-correlations better than linear theory across a wider range of scales, with applications to kSZ analyses.