KiDS andEuclid: Cosmological implications of a pseudo angular power spectrum analysis of KiDS-1000 cosmic shear tomography
Astronomy & Astrophysics EDP Sciences 665 (2022) A56-A56
Abstract:
We present a tomographic weak lensing analysis of the Kilo Degree Survey Data Release 4 (KiDS-1000), using a new pseudo angular power spectrum estimator (pseudo-C) under development for the ESA Euclid mission. Over 21 million galaxies with shape information are divided into five tomographic redshift bins, ranging from 0.1 to 1.2 in photometric redshift. We measured pseudo-Cusing eight bands in the multipole range 76<<1500 for auto- and cross-power spectra between the tomographic bins. A series of tests were carried out to check for systematic contamination from a variety of observational sources including stellar number density, variations in survey depth, and point spread function properties. While some marginal correlations with these systematic tracers were observed, there is no evidence of bias in the cosmological inference. B-mode power spectra are consistent with zero signal, with no significant residual contamination from E/B-mode leakage. We performed a Bayesian analysis of the pseudo-Cestimates by forward modelling the effects of the mask. Assuming a spatially flat CDM cosmology, we constrained the structure growth parameter S8 = 8(Ωm/0.3)1/2 = 0.7540.029+0.027. When combining cosmic shear from KiDS-1000 with baryon acoustic oscillation and redshift space distortion data from recent Sloan Digital Sky Survey (SDSS) measurements of luminous red galaxies, as well as the Lyman-α forest and its cross-correlation with quasars, we tightened these constraints to S8=0.7710.032+0.006. These results are in very good agreement with previous KiDS-1000 and SDSS analyses and confirm a 3 tension with early-Universe constraints from cosmic microwave background experiments
Constraining a late time transition of Geff using low-z galaxy survey data
Phys. Rev. D 106, 023526
Abstract:
It has recently been pointed out that a gravitational transition taking place at a recent redshift zt, reducing the effective gravitational constant Geff by about 10% for z>zt, has the potential to lead to a resolution of the Hubble tension if zt≲0.01. Since H(z)2∼Geff, such a transition would also lead to sharp change of the slope of the Hubble diagram at z=zt and a sharp decrease in the number of galaxies per redshift bin at zt. Here we attempt to impose constraints on such a transition by using two robust low-z redshift survey datasets (z<0.01), taken from the Six-degree Field Galaxy Survey (6dFGS) as well as the 2MASS Redshift Survey (2MRS). In both surveys, we bin the data in redshift bins and focus on the number of galaxies in each bin (ΔN(zi)). We observe a peak in the distribution of galaxies near a distance of approximately 20 Mpc in both datasets. This feature could be attributed to galactic density fluctuations, to coherent peculiar velocities of galaxies or to an ultra late-time gravitational transition in the same era. In the context of the later scenario we show that this feature could have been induced by a sharp change of Geff by ΔGeff/Geff≃0.6 at zt≃0.005. Thus, in a conservative approach, this method can be used to impose constraints on a possible abrupt change of the gravitational constant taking place at very low redshifts.
The role of redundancy in blind signal estimation for multiple gravitational wave detectors
World Scientific Publishing (2022) 71-83
Inferring dark matter halo properties for HI-selected galaxies
(2022)
New horizons for fundamental physics with LISA
Living Reviews in Relativity Springer 25:1 (2022) 4