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AUTHOR Park, Changbom,Dong, Fuyu
TITLE Detection of a Cross-correlation between Cosmic Microwave Background Lensing and Low-density Points
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JOURNAL ASTROPHYSICAL JOURNAL, 2021
ABSTRACT Low-density points (LDPs), obtained by removing high-density regions of observed galaxies, can trace the large-scale structures (LSSs) of the universe. In particular, it offers an intriguing opportunity to detect weak gravitational lensing from low-density regions. In this work, we investigate the tomographic cross-correlation between Planck cosmic microwave background (CMB) lensing maps and LDP-traced LSSs, where LDPs are constructed from the DR8 data release of the DESI legacy imaging survey, with about 10(6)-10(7) galaxies. We find that, due to the large sky coverage (20,000 deg(2)) and large redshift depth (z <= 1.2), a significant detection (10 sigma-30 sigma) of the CMB lensing-LDP cross-correlation in all six redshift bins can be achieved, with a total significance of similar to 53 sigma over l <= 1024. Moreover, the measurements are in good agreement with a theoretical template constructed from our numerical simulation in the WMAP 9 yr ?CDM cosmology. A scaling factor for the lensing amplitude A (lens) is constrained to A (lens) = 1 +/- 0.12 for z < 0.2, A (lens) = 1.07 +/- 0.07 for 0.2 < z < 0.4, and A (lens) = 1.07 +/- 0.05 for 0.4 < z < 0.6, with the r-band absolute magnitude cut of -21.5 for LDP selection. A variety of tests have been performed to check the detection reliability against variations in LDP samples and galaxy magnitude cuts, masks, CMB lensing maps, multipole l cuts, sky regions, and photo-z bias. We also perform a cross-correlation measurement between CMB lensing and galaxy number density, which is consistent with the CMB lensing-LDP cross-correlation. This work therefore further convincingly demonstrates that LDP is a competitive tracer of LSS.
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