Primordial Non-Gaussianity from the 21 cm Power Spectrum during the Epoch of Reionization

Primordial non-Gaussianity is a crucial test of inflationary cosmology. We consider the impact of non-Gaussianity on the ionization power spectrum from 21 cm emission at the epoch of reionization. We focus on the power spectrum on large scales at redshifts of 7 to 8 and explore the expected constraint on the local non-Gaussianity parameter f_(NL) for current and next-generation 21 cm experiments. We show that experiments such as SKA and MWA could measure f_(NL) values of order 10. This can be improved by an order of magnitude with a fast-Fourier transform telescope like Omniscope

Radio Galaxy populations and the multi-tracer technique: pushing the limits on primordial non-Gaussianity

We explore the use of different radio galaxy populations as tracers of different mass halos and therefore, with different bias properties, to constrain primordial non-Gaussianity of the local type. We perform a Fisher matrix analysis based on the predicted auto and cross angular power spectra of these populations, using simulated redshift distributions as a function of detection flux and the evolution of the bias for the different galaxy types (Star forming galaxies, Starburst galaxies, Radio-Quiet Quasars, FRI and FRII AGN galaxies). We show that such a multi-tracer analysis greatly improves the information on non-Gaussianity by drastically reducing the cosmic variance contribution to the overall error budget. By using this method applied to future surveys, we predict a constraint of sigma_fnl=3.6 on the local non-Gaussian parameter for a galaxy detection flux limit of 10 \muJy and sigma_fnl=2.2 for 1 \muJy. We show that this significantly improves on the constraints obtained when using the whole undifferentiated populations (sigma_fnl=48 for 10 \muJy and sigma_fnl=12 for 1 \muJy). We conclude that continuum radio surveys alone have the potential to constrain primordial non-Gaussianity to an accuracy at least a factor of two better than the present constraints obtained with Planck data on the CMB bispectrum, opening a window to obtain sigma_fnl~1 with the Square Kilometer Array.Comment: 9 pages, 5 figures, submitted to MNRA

O reflexo dos estilos parentais no jogo infantil

Dissertação de Mestrado apresentada ao Instituto Superior de Psicologia Aplicada para obtenção de grau de Mestre na especialidade de Psicologia Educacional.O presente trabalho, tem como principal objectivo compreender se existe alguma relação entre, os diferentes estilos parentais (Baumerind, 1971) e o tipo de jogo social. Sabese que, por um lado, a forma como a criança brinca, assume um papel importante na compreensão do seu desenvolvimento emocional, social e cognitivo, e por outro, que as práticas parentais às quais as crianças são expostas, influenciam os resultados das crianças. A amostra foi constituída pelos pais de 62 crianças com idades compreendidas entre o 4 e 5 anos, e seus respectivos educadores de infância. Para a análise dos estilos parentais utilizou-se o Parenting Practices Questionnaire, traduzido de C.C. Robinson, B. Mandleco, S.F. Olsen, & C.H. Hart (1995), e para a avaliação do tipo de jogo foi utilizado o Penn Interactive Peer Play Scale (Fantuzzo, Sutton-Smith, Atkins, Meyers, Stevenson & Coolahan, 1995). Os resultados encontrados permitem concluir que existem correlações entre as práticas parentais e o tipo de actividade social da criança, nomeadamente a que se reflecte no jogo. No entanto, os resultados que nos permitem inferir sobre a relação dos diferentes estilos parentais com o tipo de jogo não foram totalmente conclusivos. Contudo, algumas hipóteses foram confirmadas, como é o caso da associação do jogo disruptivo com o estilo parental permissivo.This work has as main objective to understand whether there is any relationship between the different parenting styles (Baumerind, 1971) and the type of social game. It is known that, firstly, how the child plays, plays an important role in understanding their emotional, social and cognitive development, and secondly, that parenting practices to which children are exposed to influence the outcome of children. The sample comprised parents of 62 children aged between 4-5, and their kindergarten teachers. For the analysis of parenting styles used the Parenting Practices Questionnaire, translated from Robinson, Mandleco, Olsen , & Hart (1995), and to assess the type of game we used the Penn Interactive Peer Play Scale (Fantuzzo, Sutton-Smith, Atkins, Meyers, Coolahan & Stevenson, 1995). The results indicated that there are correlations between parenting practices and the type of social activity of the child, including that reflected in the game. However, the results allow us to infer about the relationship of the different parenting styles with the type of game were not fully conclusive. However, some hypotheses were confirmed, as is the case of the association of disruptive game with permissive parenting style

Constraints on CDM cosmology from galaxy power spectrum, CMB and SNIa evolution

We examine the constraints that can be obtained on standard cold dark matter models from the most currently used data set: CMB anisotropies, type Ia supernovae and the SDSS luminous red galaxies. We also examine how these constraints are widened when the equation of state parameter $w$ and the curvature parameter $\Omega_k$ are left as free parameters. For the $\Lambda$CDM model, our 'vanilla' model, cosmological parameters are tightly constrained and consistent with current estimates from various methods. When the dark energy parameter $w$ is free we find that the constraints remain mostly unchanged, i.e. changes are smaller than the 1 sigma uncertainties. Similarly, relaxing the assumption of a flat universe leads to nearly identical constraints on the dark energy density parameter of the universe $\Omega_\Lambda$, baryon density of the universe $\Omega_b$, the optical depth $\tau$, the index of the power spectrum of primordial fluctuations $n_S$, with most one sigma uncertainties better than 5%. More significant changes appear on other parameters: while preferred values are almost unchanged, uncertainties for the physical dark matter density $\Omega_ch^2$, Hubble constant $H_0$ and $\sigma_8$ are typically twice as large. We found that different methodological approaches on large scale structure estimates lead to appreciable differences in preferred values and uncertainty widths. We also found that possible evolution in SNIa intrinsic luminosity does not alter these constraints by much, except for $w$, for which the uncertainty is twice as large. At the same time, this possible evolution is severely constrained. We conclude that systematic uncertainties for some estimated quantities are similar or larger than statistical ones.Comment: Revised version, 9 pages, 8 figures, accepted for publication in A&

IRS : from constitutional model to the legal (in)concretization : a retrospective and prospective vision

Dissertação de mestrado em Direito (Ciências Jurídico-Políticas / Direito Fiscal) apresentada à Faculdade de Direito da Universidade de CoimbraO n.º 1 do artigo 104.º da Constituição determina o recorte específico que o imposto sobre o rendimento pessoal deve assumir, atribuindo-lhe a finalidade de diminuição das desigualdades e consagrando as características de unicidade, progressividade e pessoalidade, ao estabelecer que o imposto sobre o rendimento pessoal “será único e progressivo, tendo em conta as necessidades e os rendimentos do agregado familiar”. Impõe-se a seguinte pergunta: terá sido este modelo efetivamente concretizado? Foram várias as específicas concretizações que este modelo tem vindo a revestir, desde o seu nascimento com a Reforma de 1988/89 até à sua conformação atual, nomeadamente com as Reformas que marcaram os anos de 2000, 2015, e bem assim, as recentes alterações introduzidas pela LOE para 2016. Estas várias alterações têm vindo a desconfigurar paulatinamente o nosso modelo de IRS. Houve momentos de maior proximidade ao modelo constitucional, mas também momentos de claro afastamento, sendo que na verdade, nunca houve ad initio uma articulação total entre estes dois planos. A tributação do rendimento pessoal apresenta-se atualmente como uma tributação dual; o princípio do rendimento líquido apresenta debilidades no que toca às deduções específicas; vigora entre nós um princípio de incomunicabilidade das perdas, e a consideração dos rendimentos e das necessidades do agregado familiar é insuficiente. Dado este quadro, aliado à tendência internacional de progressiva concorrência fiscal, é preciso repensar a estrutura do nosso sistema de imposto sobre o rendimento pessoal. Uma das alternativas poderá ser o modelo flat tax. Abstract The article 104, paragraph 1, of the Constitution determines the specific cut the tax on personal income should take. Determines that should reducing inequalities and consecrating the uniqueness characteristics, progressiveness and personhood, to establish the tax on personal income " will be unique and progressive, taking into account the needs and household income ." It must be the following question: was this actually implemented model? There were several specific embodiments of this model has been put, from the birth with the Reformation 1988/89 to its current conformation, in particular with the reforms that marked the years 2000, 2015 and as well as the recent changes introduced by the LOE for 2016. These various changes have been gradually unset our IRS model. There were moments of greater proximity to the constitutional model, but also moments of clear departure, and in fact, there has never been ad initio total articulation between these two planes. Taxation of personal income is presented today as a dual taxation; the principle of net income presents weaknesses in relation to specific deductions; exist a uncommunicate of losses principle and the consideration of income and household needs is insufficient. Given this framework, with the international trend of progressive tax competition, we need to rethink the structure of our tax system on personal income. A alternative may be the flat tax mode

Cosmological parameter extraction and biases from type Ia supernova magnitude evolution

We study different one-parametric models of type Ia Supernova magnitude evolution on cosmic time scales. Constraints on cosmological and Supernova evolution parameters are obtained by combined fits on the actual data coming from Supernovae, the cosmic microwave background, and baryonic acoustic oscillations. We find that data prefer a magnitude evolution such that high-redshift Supernova are brighter than would be expected in a standard cosmos with a dark energy component. Data however are consistent with non-evolving magnitudes at the one-sigma level, except special cases. We simulate a future data scenario where SN magnitude evolution is allowed for, and neglect the possibility of such an evolution in the fit. We find the fiducial models for which the wrong model assumption of non-evolving SN magnitude is not detectable, and for which at the same time biases on the fitted cosmological parameters are introduced. Of the cosmological parameters the overall mass density has the strongest chances to be biased due to the wrong model assumption. Whereas early-epoch models with a magnitude offset ~z^2 show up to be not too dangerous when neglected in the fitting procedure, late epoch models with magnitude offset ~sqrt(z) have high chances to bias the fit results.Comment: 12 pages, 5 figures, 3 tables. Accepted for publication by A&A. Revised version: Corrected Typos, reference added to section

Cosmology with X-ray Cluster Baryons

X-ray cluster measurements interpreted with a universal baryon/gas mass fraction can theoretically serve as a cosmological distance probe. We examine issues of cosmological sensitivity for current (e.g. Chandra X-ray Observatory, XMM-Newton) and next generation (e.g. Con-X, XEUS) observations, along with systematic uncertainties and biases. To give competitive next generation constraints on dark energy, we find that systematics will need to be controlled to better than 1% and any evolution in f_gas (and other cluster gas properties) must be calibrated so the residual uncertainty is weaker than (1+z)^{0.03}.Comment: 6 pages, 5 figures; v2: 13 pages, substantial elaboration and reordering, matches JCAP versio

Fast Large Volume Simulations of the 21 cm Signal from the Reionization and pre-Reionization Epochs

While limited to low spatial resolution, the next generation low-frequency radio interferometers that target 21 cm observations during the era of reionization and prior will have instantaneous fields-of-view that are many tens of square degrees on the sky. Predictions related to various statistical measurements of the 21 cm brightness temperature must then be pursued with numerical simulations of reionization with correspondingly large volume box sizes, of order 1000 Mpc on one side. We pursue a semi-numerical scheme to simulate the 21 cm signal during and prior to Reionization by extending a hybrid approach where simulations are performed by first laying down the linear dark matter density field, accounting for the non-linear evolution of the density field based on second-order linear perturbation theory as specified by the Zel'dovich approximation, and then specifying the location and mass of collapsed dark matter halos using the excursion-set formalism. The location of ionizing sources and the time evolving distribution of ionization field is also specified using an excursion-set algorithm. We account for the brightness temperature evolution through the coupling between spin and gas temperature due to collisions, radiative coupling in the presence of Lyman-alpha photons and heating of the intergalactic medium, such as due to a background of X-ray photons. The hybrid simulation method we present is capable of producing the required large volume simulations with adequate resolution in a reasonable time so a large number of realizations can be obtained with variations in assumptions related to astrophysics and background cosmology that govern the 21 cm signal.Comment: 14 pages and 15 figures. New version to match accepted version for MNRAS. Code available in: http://www.SimFast21.or