Dark Energy Survey Year 3 results: Magnification modeling and impact on cosmological constraints from galaxy clustering and galaxy-galaxy lensing

Abstract

We study the effect of magnification in the Dark Energy Survey Year 3 analysis of galaxy clustering and galaxy-galaxy lensing, using two different lens samples: a sample of Luminous red galaxies, redMaGiC, and a sample with a redshift-dependent magnitude limit, MagLim. We account for the effect of magnification on both the flux and size selection of galaxies, accounting for systematic effects using the Balrog image simulations. We estimate the impact of magnification on the galaxy clustering and galaxy-galaxy lensing cosmology analysis, finding it to be a significant systematic for the MagLim sample. We show cosmological constraints from the galaxy clustering auto-correlation and galaxy-galaxy lensing signal with different magnifications priors, finding broad consistency in cosmological parameters in $\Lambda$CDM and $w$CDM. However, when magnification bias amplitude is allowed to be free, we find the two-point correlations functions prefer a different amplitude to the fiducial input derived from the image simulations. We validate the magnification analysis by comparing the cross-clustering between lens bins with the prediction from the baseline analysis, which uses only the auto-correlation of the lens bins, indicating systematics other than magnification may be the cause of the discrepancy. We show adding the cross-clustering between lens redshift bins to the fit significantly improves the constraints on lens magnification parameters and allows uninformative priors to be used on magnification coefficients, without any loss of constraining power or prior volume concerns.

Version accepted for publication in MNRAS. 21 pages, 13 figures, See this https://www.darkenergysurvey.org/des-year-3-cosmology-results-papers/ URL for the full DES Y3 cosmology release

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• Magnification Bias Estimators for Realistic Surveys: an Application to the BOSS Survey
• Constraining gravity with a new precision $E_G$ estimator using Planck + SDSS BOSS
• Dark Energy Survey Year 3 Results: Redshift Calibration of the MagLim Lens Sample from the combination of SOMPZ and clustering and its impact on Cosmology
• A method of weak lensing reconstruction through cosmic magnification with multi-band photometry information
• Euclid: Photometric redshift calibration with the clustering redshifts technique
• Challenges in Cosmic Magnification Reconstruction by Magnification Response
• Weak Gravitational Lensing
• Doppler bias: impact of peculiar velocities on color selection and the large scale structure of galaxy surveys
• Linear Relativistic Corrections in the Spherical Fourier-Bessel Power Spectrum
• Weak Lensing Reconstruction by Counting DECaLS Galaxies
• 6x2pt: Forecasting gains from joint weak lensing and galaxy clustering analyses with spectroscopic-photometric galaxy cross-correlations
• First measurement of the Hubble constant from a combined weak lensing and gravitational-wave standard siren analysis
• Improving Photometric Galaxy Clustering Constraints With Cross-Bin Correlations
• Detecting Local and Integrated Relativistic Effects by Multi-Tracing a Single Galaxy Population in Harmonic Space
• Prospects for measuring the Doppler magnification dipole with LSST and DESI