Studying the largest scales in the Universe with the kinetic Sunyaev-Zel'dovich effect

As we progress further into the era of precision cosmology, new avenues to test our fundamental models of the Universe are opening up. This Ph.D. thesis is concerned with the development and understanding of a technique known as kinetic Sunyaev-Zel'dovich (kSZ) velocity reconstruction, which aims to extract information about the Universe on the largest accessible scales using measurements of the Cosmic Microwave Background (CMB) anisotropies sourced by the kSZ effect and data from galaxy redshift surveys. kSZ velocity reconstruction estimates the remote CMB dipole, i.e. the l=1 multipole moment of the observed CMB sky as seen by observers on our past lightcone. This observable probes cosmological perturbations on scales of several Gpc, and thus has the potential to be a valuable source of information on the fundamental early Universe phenomena that leaves imprints on such scales. Preliminary forecasts from the foundational literature on kSZ velocity reconstruction indicate that high signal to noise reconstructions of the remote dipole will be possible in the context of next generation CMB experiments and galaxy surveys. The goal of this thesis is to further develop the technical details of the technique and provide motivation for its use as a tool to probe physics on ultra-large scales. Chapter 1 elaborates on the motivation behind this thesis and provides a review of the key material necessary to understand kSZ velocity reconstruction. Chapter 2 presents an extended formalism for kSZ velocity reconstruction, which describes new sources of noise and bias and incorporates more realistic experimental conditions. Forecasts for the reconstruction of the remote dipole are presented in the same chapter, and these show that high signal to noise is still achievable using the new estimators. Chapter 3 presents the first suite of N-body simulations of remote dipole reconstruction on our past lightcone, which implement a novel methodology to treat the wide range of scales involved in kSZ velocity reconstruction (tens of Mpc to tens of Gpc). These simulations were used to test the robustness of the reconstruction technique against the effects of gravitational non-linearities, redshift space distortions, and CMB lensing. Additionally, these simulations were used to demonstrate the relevance of large scale contributions to the remote dipole that are not captured by other approaches to kSZ velocity reconstruction. Chapter 4 presents an analysis of parameter constraints on CMB anomalies models, aimed to demonstrate that the reconstructed remote CMB dipole and the reconstructed remote CMB quadrupole (obtained using a similar technique to kSZ velocity reconstruction) can help us go beyond the constraints achievable with traditional probes of the anomalies like the primary CMB temperature, primary CMB polarization, and large-scale galaxy distribution

Estabilidad lineal de agujeros negros

Tesis (Lic. en Física)--Universidad Nacional de Córdoba, Facultad de Matemática, Astronomía, Física y Computación, 2016.Se estudia la existencia de energías conservadas para las perturbaciones lineales con simetría axial en la región exterior del agujero negro de Schwarzschild, para perturbaciones que no han alcanzado el horizonte. Con dichas cantidades, se construyen cotas para la perturbación en la región exterior del agujero negro mediante técnicas de análisis funcional y desigualdades geométricas.The existence of conserved energies for linear and axially symmetric perturbations of the exterior of the Schwarzschild black hole is studied, in particular for those perturbations which have not reached the event horizon. Using these conserved quantities, bounds for the linear perturbation are constructed with help of functional analysis and geometrical inequalities technics

The Simons Observatory: Astro2020 Decadal Project Whitepaper

The Simons Observatory (SO) is a ground-based cosmic microwave background (CMB) experiment sited on Cerro Toco in the Atacama Desert in Chile that promises to provide breakthrough discoveries in fundamental physics, cosmology, and astrophysics. Supported by the Simons Foundation, the Heising-Simons Foundation, and with contributions from collaborating institutions, SO will see first light in 2021 and start a five year survey in 2022. SO has 287 collaborators from 12 countries and 53 institutions, including 85 students and 90 postdocs. The SO experiment in its currently funded form ('SO-Nominal') consists of three 0.4 m Small Aperture Telescopes (SATs) and one 6 m Large Aperture Telescope (LAT). Optimized for minimizing systematic errors in polarization measurements at large angular scales, the SATs will perform a deep, degree-scale survey of 10% of the sky to search for the signature of primordial gravitational waves. The LAT will survey 40% of the sky with arc-minute resolution. These observations will measure (or limit) the sum of neutrino masses, search for light relics, measure the early behavior of Dark Energy, and refine our understanding of the intergalactic medium, clusters and the role of feedback in galaxy formation. With up to ten times the sensitivity and five times the angular resolution of the Planck satellite, and roughly an order of magnitude increase in mapping speed over currently operating ("Stage 3") experiments, SO will measure the CMB temperature and polarization fluctuations to exquisite precision in six frequency bands from 27 to 280 GHz. SO will rapidly advance CMB science while informing the design of future observatories such as CMB-S4

Presentazione del documento

The Simons Observatory (SO) is a new cosmic microwave background experiment being built on Cerro Toco in Chile, due to begin observations in the early 2020s. We describe the scientific goals of the experiment, motivate the design, and forecast its performance. SO will measure the temperature and polarization anisotropy of the cosmic microwave background in six frequency bands centered at: 27, 39, 93, 145, 225 and 280 GHz. The initial configuration of SO will have three small-aperture 0.5-m telescopes and one large-aperture 6-m telescope, with a total of 60,000 cryogenic bolometers. Our key science goals are to characterize the primordial perturbations, measure the number of relativistic species and the mass of neutrinos, test for deviations from a cosmological constant, improve our understanding of galaxy evolution, and constrain the duration of reionization. The small aperture telescopes will target the largest angular scales observable from Chile, mapping ≈ 10% of the sky to a white noise level of 2 μK-arcmin in combined 93 and 145 GHz bands, to measure the primordial tensor-to-scalar ratio, r, at a target level of σ(r)=0.003. The large aperture telescope will map ≈ 40% of the sky at arcminute angular resolution to an expected white noise level of 6 μK-arcmin in combined 93 and 145 GHz bands, overlapping with the majority of the Large Synoptic Survey Telescope sky region and partially with the Dark Energy Spectroscopic Instrument. With up to an order of magnitude lower polarization noise than maps from the Planck satellite, the high-resolution sky maps will constrain cosmological parameters derived from the damping tail, gravitational lensing of the microwave background, the primordial bispectrum, and the thermal and kinematic Sunyaev-Zel'dovich effects, and will aid in delensing the large-angle polarization signal to measure the tensor-to-scalar ratio. The survey will also provide a legacy catalog of 16,000 galaxy clusters and more than 20,000 extragalactic sources

The Simons Observatory: Astro2020 Decadal Project Whitepaper

International audienceThe Simons Observatory (SO) is a ground-based cosmic microwave background (CMB) experiment sited on Cerro Toco in the Atacama Desert in Chile that promises to provide breakthrough discoveries in fundamental physics, cosmology, and astrophysics. Supported by the Simons Foundation, the Heising-Simons Foundation, and with contributions from collaborating institutions, SO will see first light in 2021 and start a five year survey in 2022. SO has 287 collaborators from 12 countries and 53 institutions, including 85 students and 90 postdocs. The SO experiment in its currently funded form ('SO-Nominal') consists of three 0.4 m Small Aperture Telescopes (SATs) and one 6 m Large Aperture Telescope (LAT). Optimized for minimizing systematic errors in polarization measurements at large angular scales, the SATs will perform a deep, degree-scale survey of 10% of the sky to search for the signature of primordial gravitational waves. The LAT will survey 40% of the sky with arc-minute resolution. These observations will measure (or limit) the sum of neutrino masses, search for light relics, measure the early behavior of Dark Energy, and refine our understanding of the intergalactic medium, clusters and the role of feedback in galaxy formation. With up to ten times the sensitivity and five times the angular resolution of the Planck satellite, and roughly an order of magnitude increase in mapping speed over currently operating ("Stage 3") experiments, SO will measure the CMB temperature and polarization fluctuations to exquisite precision in six frequency bands from 27 to 280 GHz. SO will rapidly advance CMB science while informing the design of future observatories such as CMB-S4