arXiv subjects

Arthur Loureiro

Publications and source records attributed to Arthur Loureiro.

22 records · Page 2Linked to original sources

arXiv2022

Fisher matrix for the angular power spectrum of multi-tracer galaxy surveys

Redshift evolution and peculiar velocities break the isotropy of cosmological surveys with respect to the directions parallel and transverse to the line of sight, limiting the accuracy of the Fourier representation to small areas and redshift ranges. In contrast to the Fourier space power spectrum, the full information about the two-point function of tracers of large-scale structure is encapsulated in the redshift-dependent angular power spectrum $C_\ell^{ij} (z_i,z_j)$ for the tracer species $i$ and $j$ at the redshift slices $z_i$ and $z_j$, expressed in harmonic space. In this paper we derive semi-analytical expressions for the multi-tracer Fisher matrix of angular power spectra, in real and in redshift space, which are exact in the linear regime of structure formation. Our expressions can be used to forecast the constraining power of galaxy surveys with many tracers and a large number of redshift slices, for which the derivation of the Fisher matrix from numerically evaluated covariance matrices may not be feasible or practical.

astro-ph.CO↗

arXiv2019

Cosmological Measurements from Angular Power Spectra Analysis of BOSS DR12 Tomography

We constrain cosmological parameters by analysing the angular power spectra of the Baryon Oscillation Spectroscopic Survey DR12 galaxies, a spectroscopic follow-up of around 1.3 million SDSS galaxies over 9,376 deg$^2$ with an effective volume of $\sim 6.5$ (Gpc $h^{-1}$)$^3$ in the redshift range $0.15 \leq z < 0.80$. We split this sample into 13 tomographic bins ($Δz = 0.05$); angular power spectra were calculated using a Pseudo-$C_{\ell}$ estimator, and covariance matrices were estimated using log-normal simulated maps. Cosmological constraints obtained from these data were combined with constraints from Planck CMB experiment as well as the JLA supernovae compilation. Considering a $w$CDM cosmological model measured on scales up to $k_{max} = 0.07h$ Mpc$^{-1}$, we constrain a constant dark energy equation-of-state with a $\sim 4\%$ error at the 1-$σ$ level: $w_0 = -0.993^{+0.046}_{-0.043}$, together with $Ω_m = 0.330\pm 0.012$, $Ω_b = 0.0505 \pm 0.002$, $S_8 \equiv σ_8 \sqrt{Ω_m/0.3} = 0.863 \pm 0.016$, and $h = 0.661 \pm 0.012$. For the same combination of datasets, but now considering a $Λ$CDM model with massive neutrinos and the same scale cut, we find: $Ω_m = 0.328 \pm 0.009$, $Ω_b = 0.05017^{+0.0009}_{-0.0008}$, $S_8 = 0.862 \pm 0.017$, and $h = 0.663^{+0.006}_{-0.007}$ and a 95\% credible interval (CI) upper limit of $\sum m_ν < 0.14$ eV for a normal hierarchy. These results are competitive if not better than standard analyses with the same dataset, and demonstrate this should be a method of choice for future surveys, opening the door for their full exploitation in cross-correlations probes.

astro-ph.CO↗

arXiv2019

Upper Bound of Neutrino Masses from Combined Cosmological Observations and Particle Physics Experiments

We investigate the impact of prior models on the upper bound of the sum of neutrino masses, $\sum m_ν$. We use data from Large Scale Structure of galaxies, Cosmic Microwave Background, Type Ia SuperNovae, and Big Bang Nucleosynthesis. We probe physically motivated neutrino mass models (respecting oscillation experiment constraints) and compare them to constraints using standard cosmological approximations. The former give a consistent upper bound of $\sum m_ν \lesssim 0.26$ eV ($95\%$ CI) and yields a strong competitive upper bound for the lightest neutrino mass species, $m_0^ν < 0.086$ eV ($95\%$ CI). By contrast one of the approximations, which is somewhat inconsistent with oscillation experiments, yields an upper bound of $\sum m_ν \lesssim 0.15$ eV ($95\%$ CI), which differs substantially from the former upper bound. We, therefore, argue that cosmological neutrino mass and hierarchy determination should be pursued using physically motivated models since approximations might lead to incorrect and nonphysical upper bounds.

astro-ph.CO↗

arXiv2015

Fourier analysis of multi-tracer cosmological surveys

We present optimal quadratic estimators for the Fourier analysis of cosmological surveys that detect several different types of tracers of large-scale structure. Our estimators can be used to simultaneously fit the matter power spectrum and the biases of the tracers - as well as redshift-space distortions (RSDs), non-Gaussianities (NGs), or any other effects that are manifested through differences between the clusterings of distinct species of tracers. Our estimators reduce to the one by Feldman, Kaiser & Peacock (ApJ 1994, FKP) in the case of a survey consisting of a single species of tracer. We show that the multi-tracer estimators are unbiased, and that their covariance is given by the inverse of the multi-tracer Fisher matrix (Abramo, MNRAS 2013; Abramo & Leonard, MNRAS 2013). When the biases, RSDs and NGs are fixed to their fiducial values, and one is only interested in measuring the underlying power spectrum, our estimators are projected into the estimator found by Percival, Verde & Peacock (MNRAS 2003). We have tested our estimators on simple (lognormal) simulated galaxy maps, and we show that it performs as expected, being either equivalent or superior to the FKP method in all cases we analyzed. Finally, we have shown how to extend the multi-tracer technique to include the 1-halo term of the power spectrum.

astro-ph.CO↗