Prof. David Alonso

Abstract:

We present constraints on the amplitude of matter fluctuations from the clustering of galaxies and their cross-correlation with the gravitational lensing convergence of the cosmic microwave background (CMB), focusing on low redshifts (z ≲ 0.3), where potential deviations from a perfect cosmological constant dominating the growth of structure could be more prominent. Specifically, we make use of data from the 2MASS photometric survey (2MPZ) and the WISE×SuperCOSMOS galaxy survey, in combination with CMB lensing data from Planck. Using a hybrid effective field theory (HEFT) approach to model galaxy bias we obtain constraints on the combination S 8 = σ 8 √(Ω m /0.3), where σ 8 is the amplitude of matter fluctuations, and Ω m is the non-relativistic matter fraction. Using a prior on Ω m based on the baryon acoustic oscillation measurements of DESI, we find S 8 = 0.79 ± 0.06, in reasonable agreement with CMB constraints. We also find that, in the absence of this prior, the data favours a value of Ω m = 0.245 ± 0.024, that is 2.8σ lower than Planck. This result is driven by the broadband shape of the galaxy auto-correlation, and may be affected by theoretical uncertainties in the HEFT power spectrum templates. We further reconstruct the low-redshift growth history, finding it to be compatible with the Planck predictions, as well as existing constraints from lensing tomography. Finally, we study our constraints on the HEFT bias parameters of the galaxy samples studied, finding them to be in reasonable agreement with coevolution predictions.

Abstract:

<jats:p>We present a harmonic-space estimator for the cross-correlation between the kinematic Sunyaev-Zel’dovich (kSZ) effect and the reconstructed galaxy momentum field that offers several practical advantages over the traditional stacking approach. The estimator is easy to deploy using relatively modest computational resources and recovers all information available in the galaxy-kSZ cross-correlation. In particular, by using well-understood power spectrum estimation techniques, its statistical uncertainties, including potential correlated uncertainties with other large-scale structure observables, can be easily and accurately estimated. Moreover, standard kSZ stacking measurements can be reconstructed exactly from the estimator at a lower computational cost, employing harmonic-space, catalog-level techniques to recover all small-scale information.</jats:p>

Abstract:

We study the projected clustering of photometric luminous red galaxies from the DESI Legacy Survey, combining their angular power spectrum, bispectrum, and cross-correlation with maps of the CMB lensing convergence from the Planck satellite. We employ a perturbative bias expansion in Eulerian space to describe the clustering of galaxies, modelling the power spectrum and bispectrum at one-loop and tree level, respectively. This allows us to use the bispectrum to self-consistently calibrate the perturbative bias parameters. We validate this model against an N-body simulation, and show that it can be used up to scales of at least kP max ≃ 0.2 h Mpc-1 and kB max ≃ 0.08 h Mpc-1, saturating the information recovered from the data. We obtain constraints on the amplitude of matter fluctuations σ 8 = 0.761 ± 0.020 and the non-relativistic matter fraction Ω m = 0.307 ± 0.015, as well as the combination S 8 ≡ σ 8 √(Ω m /0.3) = 0.769 ± 0.020. Including the galaxy bispectrum leads to a 10–20% improvement on the cosmological constraints, which are also in good agreement with previous analyses of the same data, and in mild tension with Planck at the ∼2.5σ level. Finally, using the bispectrum allows for a substantially more precise measurement of the bias parameters of this sample, which are in reasonable agreement with existing coevolution relations.

Abstract:

Context. Angular redshift fluctuations (ARFs) are a new cosmological observable recently proposed in the literature. It measures the 2D angular deviations of the average redshift of a given matter tracer under an input redshift shell. Since it depends on galaxy bias, it can be used to constrain primordial non-Gaussianity through the scale-dependent bias effect. Aims. We analyzed a sample of quasars built on Gaia satellite and unWISE data, Quaia to measure the local non-Gaussianity parameter f NL . This sample is particularly suitable for measuring f NL due to its large volume coverage. Methods. We measured the ARF power spectra from the Quaia catalog and combined their information with the 2D (projected) galaxy density and their cross-correlation with the Planck PR4 cosmic microwave background lensing maps to jointly constrain f NL . Results. Assuming the universality relation, we measure f NL = −3 ± 14 at the 68% confidence level by combining Quaia quasar angular density and ARFs with their CMB lensing cross-correlations. Neglecting the ARF – CMB lensing cross-correlation leads to a significant improvement in the model’s goodness-of-fit and yields comparable constraints, f NL = −5 −15 +16 . This result is the second tightest constraint on f NL using LSS two-point statistics to date and the best measurement achieved using two-point projected summary statistics, improving the previous measurement from Quaia by up to ∼25%. Our results support the inclusion of ARFs as an additional cosmological observable in future 2D analyses of upcoming datasets from large surveys.