The microwave band is a powerful observational tool to study the primordial Universe, in particular analysing the cosmic microwave background (CMB). Maps from cm to sub-mm derived with COBE, WMAP and Planck, complemented by other data, allow to greatly improve our comprehension of the Universe. These surveys contain also information on Galactic foregrounds, thermal and kinetic Sunyaev-Zeldovich effects from galaxy clusters and extragalactic point sources. Recent and forthcoming radio facilities, such as ATCA, ALMA, SKA and its precursors and pathfinders, are and will be useful to study many topics relevant for astrophysics and cosmology. In Chapter 1, I present an overview of recent Planck cosmological and astrophysical results. I study the impact of the large-angle WMAP and Planck CMB polarization datasets publicly released on the estimation of cosmological parameters of the LambdaCDM model. To complement large-angle polarization, I consider high resolution datasets from WMAP and Planck. The relevance for several parameters is investigated, focussing on cosmological reionization optical depth, amplitude of primordial fluctuations, Hubble constant, and discussing the so-called “tension” problem. In Chapter 2, I present our recent polarimetric observations of a sample of 104 compact extragalactic radio sources at 20 and 2 GHz, combined with our previous observations in six bands between 5.5 and 38 GHz, and extended in total intensity to 70 MHz with GLEAM data. They are used to investigate polarization degree frequency dependence for different spectrally-selected populations and source counts in polarization down to 1 mJy. Total intensity data from 5.5 to 38 GHz could be interpreted in terms of single component emission, while extending the analysis in frequency and polarization reveals at least two emission components, interpreted as an evidence of recurrent activity, for 90% of our sources. In Chapter 3, I derive the median polarization degree of extragalactic sources originally analyzing Planck products with the intensity distribution analysis, to characterize how unresolved sources can bias primordial CMB B-modes measurements depending to tensor-to-scalar ratio. The median polarization fraction of extragalactic radio sources is found to be of 2.75%. No polarization signal is detected for dusty galaxies, with (90% c.l.) upper limits of 2.2% at 353 GHz and 3.8% at 217 GHz. In Chapter 4, I briefly describe the SKA, its scientific goals, precursors and pathfinders. I characterize the CMB free-free spectral distortion accounting for the clumping amplification effect, increasing at decreasing redshift and depending on dark matter (DM) properties. The signal, predicted for selected reionization histories, is studied in the view of future observational perspectives. Considering also extragalactic radio source confusion noise, the free-free signal shows a favourite window at few GHz (while the predicted HI 21-cm background is mostly important at 0.1-0.2 GHz). Thus, following a deep comprehension of reionization, free-free could be used to test DM properties. Finally, I address the SKA contribution to foreground analyses for future CMB polarization projects. In Chapter 5, I discuss the boosting effects on CMB, cosmic infrared background (CIB) and thermal SZ effect due to the observer peculiar motion with respect to CMB rest frame, and investige the perspectives of future space missions. The improvements offered by e.g. CORE will provide a more accurate CMB dipole estimate. The extension of boosting effects to polarization and cross-correlations in the determination of purely velocity-driven effects is discussed. Precise inter-frequency calibration will offer the opportunity to constrain or even detect CMB spectral distortions without precise absolute calibration. The expected improvement with respect to COBE-FIRAS is discussed for early and late processes and CIB spectrum, probing early star formation history phases.

La regione spettrale delle microonde è particolarmente rilevante per lo studio dell’universo primordiale, specie tramite il fondo cosmico a microonde (CMB). Mappe dal cm al sub-mm da COBE, WMAP e Planck hanno migliorato la nostra comprensione dell’universo. Esse contengono informazioni anche su foreground galattici, effetti Sunyaev-Zeldovich (termico e cinetico), sorgenti puntiformi extragalattiche. Infrastrutture radio come ATCA, ALMA, SKA e suoi precursori e pathfinder, sono e saranno utili per studiare molte tematiche astrofisiche e cosmologiche. Nel Capitolo 1, presento alcuni risultati di Planck, cosmologici e astrofisici. Studio l’impatto dei dati pubblici di WMAP e Planck sulla polarizzazione del CMB su larga scala per la stima dei parametri del modello di LambdaCDM. Per integrare questa informazione, ho considerato set di dati ad alta risoluzione da WMAP e Planck. Viene investigata la rilevanza per vari parametri, in particolare la profondità ottica della reionizzazione cosmologica, l’ampiezza delle perturbazioni primordiali, la costante di Hubble, discutendo il cosiddetto problema della “tensione”. Nel Capitolo 2, presento le nostre osservazioni polarimetriche di 104 radiosorgenti extragalattiche a 20 e 2 GHz, combinate con le nostre osservazioni precedenti in sei bande tra 5.5 e 38 GHz, ed estese in intensità totale a 70 MHz con GLEAM. Vengono quindi studiate la dipendenza in frequenza del grado di polarizzazione per diverse popolazioni selezionate spettralmente e i conteggi di sorgenti in polarizzazione giù fino a 1 mJy. I dati in intensità totale da 5.5 a 38 GHz si possono interpretare in termini di emissione a componente singola. Estensioni in frequenza e polarizzazione rivelano l’esistenza di almeno due componenti, evidenza di attività ricorrente, per il 90% delle nostre sorgenti. Nel Capitolo 3, derivo il grado di polarizzazione mediano delle sorgenti extragalattiche analizzando i prodotti di Planck con l’analisi della distribuzione di intensità e studio come le sorgenti non risolte contaminino le misure dei modi B primordiali del CMB a seconda del rapporto tensore-scalare. La frazione di polarizzazione mediana delle radiosorgenti extragalattiche risulta del 2.75%. Per le galassie polverose, si trovano invece limiti superiori (al 90% di l.c.) di 2.2% a 353 GHz e 3.8% a 217 GHz. Nel Capitolo 4, descrivo brevemente SKA, i suoi obiettivi, precursori e pathfinder. Caratterizzo la distorsione spettrale del CMB da free-free includendo l’amplificazione da clumping, collegata alle proprietà della materia oscura (DM). Tale segnale viene studiato in vista delle future prospettive osservative. Considerando anche il rumore di confusione delle sorgenti extragalattiche, la finestra osservativa favorevole risulta a pochi GHz (mentre il segnale del fondo dell’HI a 21cm è particolare rilievo a 0.1-0.2 GHz). Perciò, compresa profondamente la reionizzazione, l’emissione di free-free potrà essere impiegata per sondare le proprietà della DM. Infine, discuto il contributo di SKA alle analisi del foreground per i futuri progetti di polarizzazione del CMB. Nel Capitolo 5, discuto gli effetti di boosting su CMB, fondo cosmico infrarosso (CIB) ed effetto SZ termico, generati dal moto peculiare dell’osservatore rispetto al sistema di riferimento in quiete con il CMB, e indago il ruolo delle future missioni spaziali. I dati da missioni quali CORE, produrranno una stima più accurata del dipolo di CMB. Viene discussa l’estensione degli effetti di boosting a polarizzazione e cross-correlazioni per la misura degli effetti puramente di velocità. Calibrazioni inter-frequenza accurate offriranno l’opportunità di vincolare (o scoprire) le distorsioni del CMB senza l’uso di calibrazioni assolute. Viene discusso il miglioramento atteso rispetto a COBE-FIRAS per processi primordiali e recenti e per lo spettro del CIB, legato alle fasi primordiali della formazione stellare.

Astrophysical and cosmological background signals from the radio to the microwaves

TROMBETTI, Tiziana
2018

Abstract

The microwave band is a powerful observational tool to study the primordial Universe, in particular analysing the cosmic microwave background (CMB). Maps from cm to sub-mm derived with COBE, WMAP and Planck, complemented by other data, allow to greatly improve our comprehension of the Universe. These surveys contain also information on Galactic foregrounds, thermal and kinetic Sunyaev-Zeldovich effects from galaxy clusters and extragalactic point sources. Recent and forthcoming radio facilities, such as ATCA, ALMA, SKA and its precursors and pathfinders, are and will be useful to study many topics relevant for astrophysics and cosmology. In Chapter 1, I present an overview of recent Planck cosmological and astrophysical results. I study the impact of the large-angle WMAP and Planck CMB polarization datasets publicly released on the estimation of cosmological parameters of the LambdaCDM model. To complement large-angle polarization, I consider high resolution datasets from WMAP and Planck. The relevance for several parameters is investigated, focussing on cosmological reionization optical depth, amplitude of primordial fluctuations, Hubble constant, and discussing the so-called “tension” problem. In Chapter 2, I present our recent polarimetric observations of a sample of 104 compact extragalactic radio sources at 20 and 2 GHz, combined with our previous observations in six bands between 5.5 and 38 GHz, and extended in total intensity to 70 MHz with GLEAM data. They are used to investigate polarization degree frequency dependence for different spectrally-selected populations and source counts in polarization down to 1 mJy. Total intensity data from 5.5 to 38 GHz could be interpreted in terms of single component emission, while extending the analysis in frequency and polarization reveals at least two emission components, interpreted as an evidence of recurrent activity, for 90% of our sources. In Chapter 3, I derive the median polarization degree of extragalactic sources originally analyzing Planck products with the intensity distribution analysis, to characterize how unresolved sources can bias primordial CMB B-modes measurements depending to tensor-to-scalar ratio. The median polarization fraction of extragalactic radio sources is found to be of 2.75%. No polarization signal is detected for dusty galaxies, with (90% c.l.) upper limits of 2.2% at 353 GHz and 3.8% at 217 GHz. In Chapter 4, I briefly describe the SKA, its scientific goals, precursors and pathfinders. I characterize the CMB free-free spectral distortion accounting for the clumping amplification effect, increasing at decreasing redshift and depending on dark matter (DM) properties. The signal, predicted for selected reionization histories, is studied in the view of future observational perspectives. Considering also extragalactic radio source confusion noise, the free-free signal shows a favourite window at few GHz (while the predicted HI 21-cm background is mostly important at 0.1-0.2 GHz). Thus, following a deep comprehension of reionization, free-free could be used to test DM properties. Finally, I address the SKA contribution to foreground analyses for future CMB polarization projects. In Chapter 5, I discuss the boosting effects on CMB, cosmic infrared background (CIB) and thermal SZ effect due to the observer peculiar motion with respect to CMB rest frame, and investige the perspectives of future space missions. The improvements offered by e.g. CORE will provide a more accurate CMB dipole estimate. The extension of boosting effects to polarization and cross-correlations in the determination of purely velocity-driven effects is discussed. Precise inter-frequency calibration will offer the opportunity to constrain or even detect CMB spectral distortions without precise absolute calibration. The expected improvement with respect to COBE-FIRAS is discussed for early and late processes and CIB spectrum, probing early star formation history phases.
BURIGANA, Carlo
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11392/2488022
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