A general analytical expression for the Gaussian covariance of complex multi-tracer power spectra is derived, applied to multipoles and 2D spectra, and validated against Monte Carlo simulations.
Large Covariance Matrices: Smooth Models from the 2-Point Correlation Function
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abstract
We introduce a new method for estimating the covariance matrix for the galaxy correlation function in surveys of large-scale structure. Our method combines simple theoretical results with a realistic characterization of the survey to dramatically reduce noise in the covariance matrix. For example, with an investment of only ~1,000 CPU hours we can produce a model covariance matrix with noise levels that would otherwise require ~35,000 mocks. Non-Gaussian contributions to the model are calibrated against mock catalogs, after which the model covariance is found to be in impressive agreement with the mock covariance matrix. Since calibration of this method requires fewer mocks than brute force approaches, we believe that it could dramatically reduce the number of mocks required to analyse future surveys.
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DESI measures BAO scales in six redshift bins with 0.52% combined precision using 5.7 million objects, detecting the signal at up to 9.1 sigma and finding larger scales than Planck LCDM at z<0.8.
DESI DR2 BAO data exhibits 2.3 sigma tension with CMB in Lambda-CDM but prefers evolving dark energy (w0 > -1, wa < 0) at 3.1 sigma with CMB and 2.8-4.2 sigma when including supernovae.
Combining LRG and ELG tracers with bias weighting improves BAO constraints by 11% on alpha_iso and 7% on alpha_AP in DESI DR1 data for the 0.8<z<1.1 bin.
citing papers explorer
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Complex yet Hermitian: Gaussian covariance of cross-correlation and multi-tracer power spectra
A general analytical expression for the Gaussian covariance of complex multi-tracer power spectra is derived, applied to multipoles and 2D spectra, and validated against Monte Carlo simulations.
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DESI 2024 III: Baryon Acoustic Oscillations from Galaxies and Quasars
DESI measures BAO scales in six redshift bins with 0.52% combined precision using 5.7 million objects, detecting the signal at up to 9.1 sigma and finding larger scales than Planck LCDM at z<0.8.
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DESI DR2 Results II: Measurements of Baryon Acoustic Oscillations and Cosmological Constraints
DESI DR2 BAO data exhibits 2.3 sigma tension with CMB in Lambda-CDM but prefers evolving dark energy (w0 > -1, wa < 0) at 3.1 sigma with CMB and 2.8-4.2 sigma when including supernovae.
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Combined tracer analysis for DESI 2024 BAO
Combining LRG and ELG tracers with bias weighting improves BAO constraints by 11% on alpha_iso and 7% on alpha_AP in DESI DR1 data for the 0.8<z<1.1 bin.