The Quijote-mfi northern sky survey at 10–20 ghz construction and study of the maps, and characterization of the microwave haze
Primordial gravitational waves generated during inflation are expected to imprint a peculiar footprint in the large angular scale polarization of the Cosmic Microwave Background (CMB), the so-called B-modes, which however are still undetected. Characterizing Galactic foregrounds such as polarized du...
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| Tipo de recurso: | tesis doctoral |
| Fecha de publicación: | 2021 |
| País: | España |
| Institución: | Universidad de La Laguna (ULL) |
| Repositorio: | RIULL. Repositorio Institucional de la Universidad de La Laguna |
| OAI Identifier: | oai:riull.ull.es:915/27330 |
| Acceso en línea: | http://riull.ull.es/xmlui/handle/915/27330 |
| Access Level: | acceso abierto |
| Palabra clave: | Cosmología Cosmogonía Astrofísica |
| Sumario: | Primordial gravitational waves generated during inflation are expected to imprint a peculiar footprint in the large angular scale polarization of the Cosmic Microwave Background (CMB), the so-called B-modes, which however are still undetected. Characterizing Galactic foregrounds such as polarized dust and synchrotron emission, as well as having very precise control of instrumental effects, is extremely important to target a clean detection of the CMB B-modes. This thesis is set in this context, and presents an analysis of the data of the MFI instrument of the QUIJOTE experiment. QUIJOTE-MFI has been installed at the Teide Observatory since 2012, with the aim to observe the intensity and linear polarization of the microwave sky at four frequencies in the range 10–20 GHz. The purpose of QUIJOTE-MFI is to measure the low frequency Galactic foregrounds such as anomalous microwave emission (AME) and polarized synchrotron, which need to be precisely characterized to complement the study of the CMB polarization anisotropies. An important part of this thesis is dedicated to the development of the PICASSO map-making code, which is based on the destriping technique (e.g., Keihänen et al., 2010), and which is used to construct the intensity and linear polarization (Stokes Q and U ) maps for the QUIJOTE experiment. PICASSO allows a precise reconstruction of the signal at large angular scales, which is key for B-modes searches. A first version of the code was initially implemented in a previous thesis by Pelaez Santos (2019), and it was further developed during this thesis by including the use of priors for the 1/f noise, and a technique for the fitting of templates in the time domain to the data, during the map-making step. PICASSO was validated with realistic simulations of QUIJOTE-MFI data, showing that the reconstruction of the sky signal is precise at the 0.001% level and for multipoles 20 ∼< ` ∼< 200. In addition, the study of the transfer function of the code showed that 100% of the sky signal is recovered at scales ` ∼> 10, with only ∼ 2% power loss at 2 ∼< ` ∼< 8 for EE and BB. This work will soon be published in Guidi et al., (submitted). Afterwards, this thesis describes the application of this code for the construction, validation, and study of the QUIJOTE-MFI wide-survey maps, which are obtained from approximately one year of effective observations of the full northern sky, at 10–20 GHz, taken in the period 2012–2018. The wide-survey maps are presented, analyzed and characterized, in conjunction with their angular power spectra. The angular power spectra of the polarization maps (which are synchrotron dominated) can be modeled, at 11 GHz, with a power law C` ∝ ` α, with α = −3.00±0.16 for EE and α = −3.09±0.41 for BB, at Galactic latitudes |b| > 5 ◦ and declinations 6 ◦ < δ < 70◦ , in the multipole range 30 < ` < 300. The relative amplitude of the power of the E and B-modes at ` = 80 is measured to be ABB/AEE = 0.34±0.10 within the aforementioned sky area, it being lower than the BB/EE ratio measured for dust emission by Planck (ABB/AEE = 0.5; Planck Collaboration et al., 2018c). The TB and EB spectra of the maps are measured to be compatible with zero within the uncertainties, and the TE spectrum is marginally detected at low multipoles. In addition, a complete set of validation tests, including the analyses of null-tests for the characterization of the noise in the maps, and cross-correlation analysis for the validation of the calibration of the data are presented. These results will be published in Rubiño-Martín et al. (in prep.), which will also be accompanied by a set of papers focused on the scientific exploitation of the QUIJOTE-MFI wide-survey data. The maps will be made publicly available. Finally, new data taken in the region surrounding the Galactic center were analyzed in combination with the wide-survey data, with the aim of studying the so-called microwave Haze. The Haze is a diffuse emission with uncertain and interesting origin, since it could be attributed to dark matter annihilation in the Galactic bulge, or to nuclear activity in the Galactic center. It extends from the Galactic center up to high Galactic latitudes (|b| < 35◦ ), with spatial correspondence to the Fermi bubbles observed in γ-rays, and to the polarized radio plumes observed by the S-PASS survey at 2.3 GHz. The Haze area is studied in intensity and in polarization, using the new data provided by the QUIJOTE experiment. An excess of diffuse signal that could be attributed to the Haze is detected in intensity with ∼ 9σ confidence level. The intensity spectrum of this emission was modeled using a power-law spectrum, leading to a spectral index βH = −2.79 ± 0.08, in the range 11–60 GHz. This result is in slight tension with previous measurements (e.g., Planck Collaboration et al., 2013) that estimated βH = −2.56 ± 0.05. However, in agreement with previous works, it can be observed that the spectrum of the the Haze is flatter than that of the total synchrotron in the same area and frequency range, which has a spectral index β s = −3.00 ± 0.03. In addition, we observed a difference between the intensity spectral index of the North and South Haze bubbles, at ∼ 6σ confidence level. Finally, a study of the polarized spurs and plumes that are possibly associated with the Haze is presented, where a clear steepening of the spectrum between 11 GHz and 23 GHz can be observed, in agreement with previous works (Carretti et al., 2013). These results will be published in Guidi et al. (in prep.). |
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