Using CMB, LSS and Galaxy Clusters as Cosmological Probes

In this thesis we have studied three independent tools to get information on cosmological parameters: the large scale structure (LSS) of matter in the Universe, galaxy clusters and the cosmic microwave background (CMB). In the study of the LSS we have provided an analytical recipe for computing the conditional mass function (CMF), i.e. the mass distribution of the halo abundance in overdense and underdense regions. We have considered a formalism already discussed in the literature and introduced an additional parameter to ensure the CMF normalisation. We have compared the predicted halo abundance from this CMF recipe with the one obtained from numerical N-body simulations, for conditions with Eulerian radii from 5 to 30 Mpc/h, and for halo masses between 10^(11) and 10^(14) M_sun/h. We have found excellent agreement with simulated abundances in underdense regions at all scales, and in overdense regions at large scales; we have also confirmed that the CMF normalisation is satisfied at all scales. We have finally presented an analytical fit to the matter-to-halo bias function in underdense regions, which could be of special interest to speed-up the computation of the halo abundance when studying void statistics. This fit is capable of reproducing the computed halo bias with an error below 2% for the reference cosmology, and below 9% when considering different values of redshift and sigma_8. With respect to the cosmology with galaxy clusters, we have considered the abundance of clusters as a function of redshift as a tool to estimate the cosmological parameters Omega_m and sigma_8. We have implemented the computation of the cluster redshift distribution according to a specified cosmology, and developed a statistical tool based on a Markov Chains Monte Carlo (MCMC) method to retrieve the cosmological parameters starting from the cluster abundance. We have applied our code to the cosmological subsample of the PSZ1 catalogue of clusters detected by the Planck satellite with signal-to-noise ratio above seven. We have obtained estimates of Omega_m and sigma_8 based on the cluster abundance in combination with BBN and BAO likelihoods, considering the bias 'b' in the determination of the cluster mass as a fixed or free parameter. With the bias parameter fixed to the value b=0.2 we found Omega_m=0.293±0.020 and sigma_8=0.760(+0.018,-0.017) (68% C.L.). With 'b' free to vary with a flat prior in the range [0.0,0.3] we found Omega_m=0.289(+0.022,-0.020) and sigma_8=0.750±0.028. These results are in very good agreement with the ones obtained by the Planck Collaboration using the same cluster catalogue. This proves the reliability of our method, that can therefore be applied in the future to broader catalogues, resulting in a significant reduction of the error bars in the estimation of these parameters. An example is the extended cosmological subsample of the PSZ1, that contains nearly three times the number of clusters employed for the analysis in this work and that will soon be made publicly available. We have employed the Sunyaev-Zel'dovich effect as a cosmological probe. To this aim we computed the one dimensional probability distribution function (PDF) of the Compton parameter 'y' measured by the Planck satellite over the whole sky; this PDF is strongly dependent on the parameter sigma_8. We have modelled the galaxy cluster contribution to the PDF and tested our formalism with simulated Compton parameter maps. We have applied this formalism to fit for sigma_8 against the PDF extracted by Planck data. We have considered only values for y>4.5*10^(-6) in order to leave out contamination from instrumental noise and other astrophysical foregrounds, and obtained the final estimate sigma_8=0.77±0.02 (68% C.L.). This result is compatible with other cluster-based estimates, and shows a tension with the value obtained from CMB analysis (~0.83). This tension may be due to systematics in the modelling or instrumental calibration or it can be the first hint for a necessary extension of the standard cosmological model. The study related to the CMB presented in this thesis is based on the QUIJOTE experiment, and on the data obtained with the multi-frequency instrument (MFI). We have carried out the pointing calibration of the first QUIJOTE telescope, developing a set of coordinate transformations to correct for the telescope non-idealities: these transformations have been implemented in the MFI data reduction pipeline and are routinely employed to achieve a pointing correction with errors below 1 minute of arc. We have considered observations of the MFI in the galactic regions W49, W51 (molecular clouds) and IC443 (supernova remnant), and assessed the relative contribution of different emission mechanisms. In particular, we have found hints of detection of anomalous microwave emission (AME) in intensity in all regions, with a higher significance in W49. We have also detected synchrotron emission in the regions W49 and IC443. This information is relevant for modelling the synchrotron emission properties in our Galaxy, and this way making the separation of the cosmological B-modes signal easier in future data from this and other experiments

QUIJOTE scientific results -- XIII. Intensity and polarization study of supernova remnants in the QUIJOTE-MFI wide survey: CTB 80, Cygnus Loop, HB 21, CTA 1, Tycho and HB 9

We use the new QUIJOTE-MFI wide survey (11, 13, 17 and 19 GHz) to produce spectral energy distributions (SEDs), on an angular scale of 1 deg, of the supernova remnants (SNRs) CTB 80, Cygnus Loop, HB 21, CTA 1, Tycho and HB 9. We provide new measurements of the polarized synchrotron radiation in the microwave range. For each SNR, the intensity and polarization SEDs are obtained and modelled by combining QUIJOTE-MFI maps with ancillary data. In intensity, we confirm the curved power law spectra of CTB 80 and HB 21 with a break frequency $\nu_{\rm b}$ at 2.0$^{+1.2}_{-0.5}$ GHz and 5.0$^{+1.2}_{-1.0}$ GHz respectively; and spectral indices respectively below and above the spectral break of $-0.34\pm0.04$ and $-0.86\pm0.5$ for CTB 80, and $-0.24\pm0.07$ and $-0.60\pm0.05$ for HB 21. In addition, we provide upper limits on the Anomalous Microwave Emission (AME), suggesting that the AME contribution is negligible towards these remnants. From a simultaneous intensity and polarization fit, we recover synchrotron spectral indices as flat as $-0.24$, and the whole sample has a mean and scatter of $-0.44\pm0.12$. The polarization fractions have a mean and scatter of $6.1\pm1.9$\%. When combining our results with the measurements from other QUIJOTE studies of SNRs, we find that radio spectral indices are flatter for mature SNRs, and particularly flatter for CTB 80 ($-0.24^{+0.07}_{-0.06}$) and HB 21 ($-0.34^{+0.04}_{-0.03}$). In addition, the evolution of the spectral indices against the SNRs age is modelled with a power-law function, providing an exponent $-0.07\pm0.03$ and amplitude $-0.49\pm0.02$ (normalised at 10 kyr), which are conservative with respect to previous studies of our Galaxy and the Large Magellanic Cloud.Comment: 33 pages, 15 figure, 15 tables. Submitted to MNRAS. QUIJOTE data maps available at https://research.iac.es/proyecto/quijot

Exploring Cosmic Origins with CORE: Cosmological Parameters

We forecast the main cosmological parameter constraints achievable with theCORE space mission which is dedicated to mapping the polarisation of the CosmicMicrowave Background (CMB). CORE was recently submitted in response to ESA'sfifth call for medium-sized mission proposals (M5). Here we report the resultsfrom our pre-submission study of the impact of various instrumental options, inparticular the telescope size and sensitivity level, and review the great,transformative potential of the mission as proposed. Specifically, we assessthe impact on a broad range of fundamental parameters of our Universe as afunction of the expected CMB characteristics, with other papers in the seriesfocusing on controlling astrophysical and instrumental residual systematics. Inthis paper, we assume that only a few central CORE frequency channels areusable for our purpose, all others being devoted to the cleaning ofastrophysical contaminants. On the theoretical side, we assume LCDM as ourgeneral framework and quantify the improvement provided by CORE over thecurrent constraints from the Planck 2015 release. We also study the jointsensitivity of CORE and of future Baryon Acoustic Oscillation and Large ScaleStructure experiments like DESI and Euclid. Specific constraints on the physicsof inflation are presented in another paper of the series. In addition to thesix parameters of the base LCDM, which describe the matter content of aspatially flat universe with adiabatic and scalar primordial fluctuations frominflation, we derive the precision achievable on parameters like thosedescribing curvature, neutrino physics, extra light relics, primordial heliumabundance, dark matter annihilation, recombination physics, variation offundamental constants, dark energy, modified gravity, reionization and cosmicbirefringence. (ABRIDGED

Robustness of cosmic neutrino background detection in the cosmic microwave background

The existence of a cosmic neutrino background can be probed indirectly by CMB experiments, not only by measuring the background density of radiation in the universe, but also by searching for the typical signatures of the fluctuations of free-streaming species in the temperature and polarisation power spectrum. Previous studies have already proposed a rather generic parametrisation of these fluctuations, that could help to discriminate between the signature of ordinary free-streaming neutrinos, or of more exotic dark radiation models. Current data are compatible with standard values of these parameters, which seems to bring further evidence for the existence of a cosmic neutrino background. In this work, we investigate the robustness of this conclusion under various assumptions. We generalise the definition of an effective sound speed and viscosity speed to the case of massive neutrinos or other dark radiation components experiencing a non-relativistic transition. We show that current bounds on these effective parameters do not vary significantly when considering an arbitrary value of the particle mass, or extended cosmological models with a free effective neutrino number, dynamical dark energy or a running of the primordial spectrum tilt. We conclude that it is possible to make a robust statement about the detection of the cosmic neutrino background by CMB experiments.Comment: version accepted for publication in JCAP. 19 pages, 7 figures, 3 tables. Minor changes. References adde

Robustness of cosmic neutrino background detection in the cosmic microwave background

The existence of a cosmic neutrino background can be probed indirectly by CMB experiments, not only by measuring the background density of radiation in the universe, but also by searching for the typical signatures of the fluctuations of free-streaming species in the temperature and polarisation power spectrum. Previous studies have already proposed a rather generic parametrisation of these fluctuations, that could help to discriminate between the signature of ordinary free-streaming neutrinos, or of more exotic dark radiation models. Current data are compatible with standard values of these parameters, which seems to bring further evidence for the existence of a cosmic neutrino background. In this work, we investigate the robustness of this conclusion under various assumptions. We generalise the definition of an effective sound speed and viscosity speed to the case of massive neutrinos or other dark radiation components experiencing a non-relativistic transition. We show that current bounds on these effective parameters do not vary significantly when considering an arbitrary value of the particle mass, or extended cosmological models with a free effective neutrino number, dynamical dark energy or a running of the primordial spectrum tilt. We conclude that it is possible to make a robust statement about the detection of the cosmic neutrino background by CMB experiments

Robustness of cosmic neutrino background detection in the cosmic microwave background

The existence of a cosmic neutrino background can be probed indirectly by CMB experiments, not only by measuring the background density of radiation in the universe, but also by searching for the typical signatures of the fluctuations of free-streaming species in the temperature and polarisation power spectrum. Previous studies have already proposed a rather generic parametrisation of these fluctuations, that could help to discriminate between the signature of ordinary free-streaming neutrinos, or of more exotic dark radiation models. Current data are compatible with standard values of these parameters, which seems to bring further evidence for the existence of a cosmic neutrino background. In this work, we investigate the robustness of this conclusion under various assumptions. We generalise the definition of an effective sound speed and viscosity speed to the case of massive neutrinos or other dark radiation components experiencing a non-relativistic transition. We show that current bounds on these effective parameters do not vary significantly when considering an arbitrary value of the particle mass, or extended cosmological models with a free effective neutrino number, dynamical dark energy or a running of the primordial spectrum tilt. We conclude that it is possible to make a robust statement about the detection of the cosmic neutrino background by CMB experiments

QUIJOTE scientific results - V. The microwave intensity and polarization spectra of the Galactic regions W49, W51 and IC443

We present new intensity and polarization maps obtained with the QUIJOTE experiment towards the Galactic regions W49, W51 and IC443, covering the frequency range from 10 to 20-GHz at ⁓1deg angular resolution, with a sensitivity in the range 35-79 µK Kbeam-1 for total intensity and 13-23 µK beam-1 for polarization. For each region, we combine QUIJOTE maps with ancillary data at frequencies ranging from 0.4 to 3000 GHz, reconstruct the spectral energy distribution and model it with a combination of known foregrounds. We detect anomalous microwave emission (AME) in total intensity towards W49 at 4.7σ and W51 at 4.0σ with peak frequencies vAME=(20.0±1.4)GHz and vAME=(17.7±3.6)GHz, respectively; this is the first detection of AME towards W51. The contamination from ultracompact HII regions to the residual AME flux density is estimated at 10 per cent in W49 and 5 per cent in W51, and does not rule out the AME detection. The polarized SEDs reveal a synchrotron contribution with spectral indices αs = -0.67 ± 0.10 in W49 and αs = -0.51 ± 0.07 in W51, ascribed to the diffuse Galactic emission and to the local supernova remnant, respectively. Towards IC443 in total intensity we measure a broken power-law synchrotron spectrum with cut-off frequency v0,s=(114±73)GHz, in agreement with previous studies; our analysis, however, rules out any AME contribution which had been previously claimed towards IC443. No evidence of polarized AME emission is detected in this study.We thank the staff of the Teide Observatory for invaluable assistance in the commissioning and operation of QUIJOTE. The QUIJOTE experiment is being developed by the Instituto de Astrofisica de Canarias (IAC), the Instituto de Fisica de Cantabria (IFCA), and the Universities of Cantabria, Manchester and Cambridge. Partial financial support was provided by the Spanish Ministry of Science and Innovation under the projects AYA2007-68058-C03-01, AYA2007-68058-C03-02, AYA2010-21766-C03-01,AYA2010-21766-C03-02, AYA2014-60438-P, ESP2015-70646-C2-1-R, AYA2017-84185-P,ESP2017-83921-C2-1-R,AYA2017-90675-REDC (co-funded with EU FEDER funds), PGC2018-101814-B-I00, PID2019-110610RB-C21, PID2020-120514GB-I00, IACA13-3E-2336, IACA15-BE-3707, EQC2018-004918-P, the Severo Ochoa Programs SEV-2015-0548 and CEX2019-000920-S, the Maria de Maeztu Program MDM-2017-0765, and by the Consolider-Ingenio project CSD2010-00064 (EPI: Exploring the Physics of Inflation). We acknowledge support from the ACIISI, Consejeria de Economia, Conocimiento y Empleo del Gobierno de Canarias and the European Regional Development Fund (ERDF) under grant with reference ProID2020010108. This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement number 687312 (RADIOFOREGROUNDS). DT acknowledges the support from the Chinese Academy of Sciences (CAS) President’s International Fellowship Initiative (PIFI) with Grant N. 2020PM0042; DT also acknowledges the support from the South African Claude Leon Foundation, that partially funded this work. EdlH acknowledges partial financial support from the Concepción Arenal Programme of the Universidad de Cantabria. FG acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 101001897). FP acknowledges the European Commission under the Marie Sklodowska-Curie Actions within the European Union’s Horizon 2020 research and innovation programme under Grant Agreement number 658499 (PolAME). FP acknowledges support from the Spanish State Research Agency (AEI) under grant numbers PID2019-105552RB-C43. BR-G acknowledges ASI-INFN Agreement 2014-037-R.0