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Abstract:

We examine, from first principles, the angular power spectrum between the kinematic Sunyaev-Zel'dovich effect (kSZ) and the reconstructed galaxy momentum — the basis of existing and future “kSZ stacking” analyses. We present a comprehensive evaluation of all terms contributing to this cross-correlation, including both the transverse and longitudinal modes of the density-weighted velocity field, as well as all irreducible correlators that contribute to the momentum power spectrum. This includes the dominant component, involving the convolution of the electron-galaxy and velocity-velocity power spectra, an additional disconnected cross-term, and a connected non-Gaussian trispectrum term. Using this framework, we examine the impact of other commonly neglected contributions, such as the two-halo component of the dominant term, and the impact of satellite galaxies. Finally, we assess the sensitivity of upcoming CMB experiments to these effects and determine that they will be sensitive to the cross-term, the connected non-Gaussian trispectrum term, the two-halo contribution and impact of satellite galaxies, at a significance level of ∼ 4-6σ. On the other hand, the contribution from longitudinal modes is negligible in all cases. These results identify the astrophysical observables that must be accurately modelled to obtain unbiased constraints on cosmology and astrophysics from near-future kSZ measurements.

Abstract:

We measure the amplitude of matter fluctuations over a wide range of redshifts by combining CMB lensing observations from ACT DR6 and Planck PR4 with the overdensity of quasars from Quaia, a Gaia and unWISE quasar catalog. Our analysis includes the CMB lensing power spectrum from ACT DR6, the auto-correlation of two Quaia quasar samples centered at z ≃ 1.0 and z ≃ 2.1, and their cross-correlations with CMB lensing from both ACT DR6 and Planck PR4. By performing a series of contamination and systematic null tests, we find no evidence for contamination in the lensing maps, contrary to what was suggested in previous Quaia cross-correlation analyses using Planck PR4 CMB lensing data. From the joint analysis of the quasar auto- and cross-correlations with CMB lensing, and including BOSS BAO data to break the degeneracy between Ω m and σ 8, we obtain σ 8 = 0.802+0.045 -0.057, consistent with ΛCDM predictions from Planck primary CMB measurements. We also find consistent results using DESI BAO data. Combining the CMB lensing auto-spectrum with the cross-correlation measurement improves the constraint on σ 8 by 12% relative to the lensing auto-spectrum alone, yielding σ 8 = 0.804 ± 0.013. This dataset combination also enables a reconstruction of structure growth across redshifts. We infer a 12% constraint on the amplitude of matter fluctuations at z > 3, with a measurement at the median redshift of the signal of σ 8(z̃ = 5.1) = 0.146+0.021 -0.014, consistent with Planck at the 1.4σ level. These results provide one of the highest redshift constraints on the growth of structure to date.

Abstract:

We present the first cosmological constraints from a joint analysis of galaxy clustering and galaxy–galaxy lensing using extended SubHalo Abundance Matching (SHAMe). We analyse stellar mass-selected Galaxy And Mass Assembly galaxy clustering and Kilo-Degree Survey (KiDS-1000) galaxy–galaxy lensing and find constraints on , in agreement with Planck at 1.7, with the mass density fluctuation amplitude in 8 sphere at present and the density parameter in total matter. These results are in agreement with the cosmic microwave background results from Planck. We are able to constrain all five SHAMe parameters, which describe the galaxy–subhalo connection. We validate our methodology by first applying it to simulated catalogues, generated from the TNG300 simulation, which mimic the stellar mass selection of our real data. We show that we are able to recover the input cosmology for both our fiducial and all-scale analyses. Our all-scale analysis extends to scales of galaxy–galaxy lensing below , which we exclude in our fiducial analysis to avoid baryonic effects. When including all scales, we find a value of , which is 1.26 higher than our fiducial result (against naive expectations where baryonic feedback should lead to small-scale power suppression), and in agreement with Planck at 0.9. We also find a 21 per cent tighter constraint on and a 29 per cent tighter constraint on compared to our fiducial analysis. This work shows the power and potential of joint small-scale galaxy clustering and galaxy–galaxy lensing analyses using SHAMe.