A novel approach in the WIMP quest: Cross-Correlation of Gamma-Ray Anisotropies and Cosmic Shear

Both cosmic shear and cosmological gamma-ray emission stem from the presence of Dark Matter (DM) in the Universe: DM structures are responsible for the bending of light in the weak lensing regime and those same objects can emit gamma-rays, either because they host astrophysical sources (active galactic nuclei or star-forming galaxies) or directly by DM annihilations (or decays, depending on the properties of the DM particle). Such gamma-rays should therefore exhibit strong correlation with the cosmic shear signal. In this Letter, we compute the cross-correlation angular power spectrum of cosmic shear and gamma-rays produced by the annihilation/decay of Weakly Interacting Massive Particle (WIMP) DM, as well as from astrophysical sources. We show that this observable provides novel information on the composition of the Extra-galactic Gamma-ray Background (EGB), since the amplitude and shape of the cross-correlation signal strongly depends on which class of source is responsible for the gamma-ray emission. If the DM contribution to the EGB is significant (at least in a definite energy range), although compatible with current observational bounds, its strong correlation with the cosmic shear makes such signal potentially detectable by combining Fermi-LAT data with forthcoming galaxy surveys, like Dark Energy Survey and Euclid. At the same time, the same signal would demonstrate that the weak lensing observables are indeed due to particle DM matter and not to possible modifications of General Relativity.Comment: 6 pages, 12 figures. v2: Matches version published in ApJ Lett. Text reorganized, appendix removed (part of the discussion is now in the main text), no major change

How bright can the brightest neutrino source be?

After the discovery of extraterrestrial high-energy neutrinos, the next major goal of neutrino telescopes will be identifying astrophysical objects that produce them. The flux of the brightest source $F_{\rm max}$, however, cannot be probed by studying the diffuse neutrino intensity. We aim at constraining $F_{\rm max}$ by adopting a broken power-law flux distribution, a hypothesis supported by observed properties of any generic astrophysical sources. The first estimate of $F_{\rm max}$ comes from the fact that we can only observe one universe, and hence, the expected number of sources above $F_{\rm max}$ cannot be too small compared with one. For abundant source classes such as starburst galaxies, this one-source constraint yields a value of $F_{\rm max}$ that is an order of magnitude lower than the current upper limits from point-source searches. Then we derive upper limits on $F_{\rm max}$ assuming that the angular power spectrum is consistent with neutrino shot noise yet. We find that the limits obtained with upgoing muon neutrinos in IceCube can already be quite competitive, especially for rare but bright source populations such as blazars. The limits will improve nearly quadratically with exposure, and therefore be even more powerful for the next generation of neutrino telescopes.Comment: 13 pages, 10 figures, accepted by Phys.Rev.

Soft-Tissue Localization of Hepatoid Adenocarcinoma: First Case Report

Hepatoid adenocarcinoma (HAC) is a rare type of extrahepatic cancer, whose pathologic features are indistinguishable from those of hepatocellular carcinoma. About thirty cases, nearly half of which occurring in the lung, have been described in patients with a normal liver. No imaging features are typical enough to allow a correct diagnosis. A localization of HAC in the soft tissues of the shoulder with invasion of the scapula in a woman without other symptoms is reported in this paper; soft-tissue HACs have never been described to date. An associate pulmonary HAC was eventually found in this patient

Gamma-Rays from Dark Matter Mini-Spikes in M31

The existence of a population of wandering Intermediate Mass Black Holes (IMBHs) is a generic prediction of scenarios that seek to explain the formation of Supermassive Black Holes in terms of growth from massive seeds. The growth of IMBHs may lead to the formation of DM overdensities called "mini-spikes", recently proposed as ideal targets for indirect DM searches. Current ground-based gamma-ray experiments, however, cannot search for these objects due to their limited field of view, and it might be challenging to discriminate mini-spikes in the Milky Way from the many astrophysical sources that GLAST is expected to observe. We show here that gamma-ray experiments can effectively search for IMBHs in the nearby Andromeda galaxy (also known as M31), where mini-spikes would appear as a distribution of point-sources, isotropically distributed in a \thickapprox 3^{\circ} circle around the galactic center. For a neutralino-like DM candidate with a mass m_{\chi}=150 GeV, up to 20 sources would be detected with GLAST (at 5\sigma, in 2 months). With Air Cherenkov Telescopes such as MAGIC and VERITAS, up to 10 sources might be detected, provided that the mass of neutralino is in the TeV range or above.Comment: 9 pages, 5 figure

Anisotropy probe of galactic and extra-galactic Dark Matter annihilations

We study the flux and the angular power spectrum of gamma-rays produced by Dark Matter (DM) annihilations in the Milky Way (MW) and in extra-galactic halos. The annihilation signal receives contributions from: a) the smooth MW halo, b) resolved and unresolved substructures in the MW, c) external DM halos at all redshifts, including d) their substructures. Adopting a self-consistent description of local and extra-galactic substructures, we show that the annihilation flux from substructures in the MW dominates over all the other components for angles larger than O(1) degrees from the Galactic Center, unless an extreme prescription is adopted for the substructures concentration. We also compute the angular power spectrum of gamma-ray anisotropies and find that, for an optimistic choice of the particle physics parameters, an interesting signature of DM annihilations could soon be discovered by the Fermi LAT satellite at low multipoles, l<100, where the dominant contribution comes from MW substructures with mass M>10^4 solar masses. For the substructures models we have adopted, we find that the contribution of extra-galactic annihilations is instead negligible at all scales.Comment: 14 pages, 7 figure

Utilização de concreto reciclado para a produção de geopolímero

TCC (graduação) - Universidade Federal de Santa Catarina. Campus Joinville. Engenharia de Infraestrutura.Um dos mais importantes setores da economia, a indústria da construção civil, se caracteriza como um dos que mais consomem recursos naturais, desde a produção até a execução da obra, o que altera significativamente a qualidade de vida da sociedade e do meio ambiente. Desde a metade do século XX a comunidade científica vem desenvolvendo tecnologias verdes ou ambientalmente corretas para tentar diminuir os impactos causados. Um material que apresenta potencial ecológico e que já existe no mercado mundial há algumas décadas é o geopolímero. Visando isto, este trabalho tem como objetivo a produção de uma argamassa geopolimérica. Os geopolímeros são produzidos a partir da polimerização de matérias primas ricas em aluminossilicatos na forma amorfa ou semi cristalina, ativadas quimicamente por uma solução alcalina. Nesta pesquisa utilizou-se como fonte de aluminossilicatos o metacaulim, quanto à solução ativadora, o hidróxido de sódio e o silicato, bem como o concreto reciclado, que tem como objetivo principal a reutilização do concreto que seriam descartados no meio ambiente e a diminuição da quantidade de areia na mistura. Para a produção das argamassas geopoliméricas foram realizados vários testes, até obter a formulação correta das frações de concreto reciclado, metacaulim e hidróxido de sódio. Encontrada a formulação correta foram feitos ensaios no estado fresco e endurecido. A formulação que obteve melhores resultados foi a que não utilizou resíduo, a resistência à flexão e a compressão desta foi maior que as demais formulações. Em contrapartida, formulação que utilizou o resíduo obteve o pior desempenho, registrou os valores mais baixos, porém aceitável em termos de resistência mecânica, de resistência à flexão e a compressão. Com isso concluiu-se, partir dos resultados que a argamassa geopolímerica possui 4,40 MPa de resistência à flexão e 20,16 MPa de resistência à compressão e, que esta pode ser utilizada para a fabricação de argamassas mais ecologicamente corretas