This paper presents a methodology that employs the electrostatic field variations caused by thundercloud formation or displacement to generate lightning warnings over a region of interest in Southeastern Brazil. These warnings can be used to prevent accidents during hazardous operations, such as the manufacturing, loading, and test of motor-rockets. In these cases, certain equipment may be moved into covered facilities and personnel are required to take shelter. It is also possible to avoid the threat of natural and triggered lightning to launches. The atmospheric electric field database, including the summer seasons of 2007/2008 and 2008/2009 (from November to February), and, for the same period and region, the cloud-to-ground lightning data provided by the Brazilian lightning detection network-BrasilDAT-were used in order to perform a comparative analysis between the lightning warnings and the cloud-toground lightning strikes that effectively occurred inside the area of concern. The analysis was done for three areas surrounding the sensor installation defined as circles with 5, 10 and 15 km of radius to determine the most effective detection range.

Investiga-se a equação de Schrödinger unidimensional com o oscilador harmônico singular. A hermiticidade dos operadores associados com quantidades físicas observáveis é usada como critério para mostrar que o oscilador singular atrativo ou repulsivo exibe um número infinito de soluções aceitáveis, contanto que o parâmetro responsável pela singularidade seja maior que um certo valor crítico, em discordância com a literatura. O problema definido em todo o eixo exibe dupla degenerescência no caso do oscilador singular e intrusão de adicionais níveis de energia no caso do oscilador não-singular. Outrossim, mostra-se que a solução do oscilador singular não pode ser obtida a partir da solução do oscilador não-singular via teoria da perturbação.

In this work, we investigate the role of emission by dust at infrared wavelengths in the absorption of gamma radiation from distant extragalactic sources, especially blazars. We use an existing EBL model based on direct starlight emission at UV/visible and secondary radiation due to dust (PAHs (polycyclic aromatic hydrocarbons), small and large grains) at IR due to partial absorption of the stellar component. The relative contribution of each grain type to the total EBL energy density was determined from a combined fit to the Markarian 501 (z∼ 0.034) SED in flare state, where both the parameters of the intrinsic source spectrum (with or without curvature) and the dust fractions were allowed to vary. By separating the attenuation due to each EBL component, the importance of individual grain types to the opacity of the extragalactic medium for the TeV emission of a blazar like Markarian 501 could be better understood. Using a nested log-likelihood ratio test, we compared null hypotheses represented by effective 1- and 2-grain models against a 3-grain alternative scenario. When the temperatures of the grains are fixed a priori, the 1-grain scenario with only PAHs can be excluded at more than 5σ (p=2.9× 10−8), irrespective of the curvature in the intrinsic spectrum. The effective 3-grain EBL model with the tuned fractions was finally used to fit the SEDs of a sample of extragalactic gamma-ray sources (dominated by blazars). Such a sample is still dominated by starlight attenuation, therefore, no statistically significant improvement in the quality of fits was observed when the tuned fractions are used to account for the EBL attenuation and the intrinsic spectrum parameters are allowed to vary during the fit. The potential of this kind of analysis when the next generation of IACTs, represented by the Cherenkov Telescope Array (CTA), starts observations is enormous. The newly discovered AGNs at a broad range of redshifts should break many of the degeneracies currently observed.

Very-High Energy (VHE) gamma-ray astroparticle physics is a relatively young field, and observations over the past decade have surprisingly revealed almost two hundred VHE emitters which appear to act as cosmic particle accelerators. These sources are an important component of the Universe, influencing the evolution of stars and galaxies. At the same time, they also act as a probe of physics in the most extreme environments known -such as in supernova explosions, and around or after the merging of black holes and neutron stars. However, the existing experiments have provided exciting glimpses, but often falling short of supplying the full answer. A deeper understanding of the TeV sky requires a significant improvement in sensitivity at TeV energies, a wider energy coverage from tens of GeV to hundreds of TeV and a much better angular and energy resolution with respect to the currently running facilities. The next generation gamma-ray observatory, the Cherenkov Telescope Array Observatory (CTAO), is the answer to this need. In this talk I will present this upcoming observatory from its design to the construction, and its potential science exploitation. CTAO will allow the entire astronomical community to explore a new discovery space that will likely lead to paradigm-changing breakthroughs. In particular, CTA has an unprecedented sensitivity to short (sub-minute) timescale phenomena, placing it as a key instrument in the future of multi-messenger and multi-wavelength time domain astronomy. I will conclude the talk presenting the first scientific results obtained by the LST-1, the prototype of one CTA telescope type -the Large Sized Telescope, that is currently under commission.

Investiga-se a equação de Schrödinger unidimensional com uma classe de potenciais V(|x|) que se anulam no infinito e apresentam singularidade dominante na origem na forma α/|x|β(0 < β < 2). A hermiticidade dos operadores associados com quantidades físicas observáveis é usada para determinar as condições de contorno apropriadas. Dupla degenerescência e exclusão de soluções simétricas, consoante o valor de β, são discutidas. Soluções explícitas para o átomo de hidrogênio e o potencial de Kratzer são apresentadas.