Production of cosmic-ray antinuclei in the Galaxy and background for dark matter searches

Antimatter nuclei in cosmic rays (CR) represent a promising discovery channel for the indirect search of dark matter. We present astrophysical background calculations of CR antideuteron ($\overline{d}$) and antihelium ($\overline{He}$). These particles are produced by high-energy collisions of CR protons and nuclei with the gas nuclei of the interstellar medium. In our calculations, we also consider production and shock acceleration of antinuclei in the shells of supernova remnants (SNRs). The total flux of $\overline{d}$ and $\overline{He}$ particles is constrained using new AMS measurements on the boron/carbon (B/C) and antiproton/proton ($\bar{p}/p$) ratios. The two ratios leads to different antiparticle fluxes in the high-energy regime $E\gtrsim$ 10 GeV/n where, in particular, $\bar{p}/p$-driven calculations leads to a significantly larger antiparticle flux in comparison to predictions from conventional B/C-driven constraints. On the other hand, both approaches provide consistent results in the sub-GeV/n energy window, which is where dark matter induced signal may exceed the astrophysical background. In this region, the total antinuclei flux, from interaction in the insterstellar gas and inside SNRs, is tightly bounded by the data. Shock-acceleration of antiparticles in SNRs has a minor influence in the astrophysical background for dark matter searches.Comment: Proceedings of the EPS Conference on High Energy Physics EPS-HEP 2017, Venic

Secondary antinuclei from supernova remnants and background for dark matter searches

We compute the spectra of cosmic-ray (CR) nuclei and antinuclei under a scenario where hadronic interaction processes inside supernova remnants (SNRs) can produce a diffusively-shock-accelerated "source component" of secondary particles. This scenario is able to explain the recent measurements reported by AMS on the antiproton/proton ratio, that is found to be remarkably constant at ~60-450 GeV of kinetic energy. However, as we will show, this explanation is ruled out by the new AMS data on the B/C ratio, which is found to decrease steadily up to TeV/n energies. With the constraints provided by the two ratios, we calculate conservative (B/C driven) and speculative (pbar/p driven) SNR-induced flux contribution for the spectra of antideuteron and antihelium in CRs, along with their standard secondary component expected from CR collisions in the interstellar gas. We found that the SNR component of anti-nuclei can be significantly large at high-energy, above a few ~10 GeV/n, but it is always sub-dominant at sub-GeV/n energies, that is, the energy region where dark-matter induced signals may exceed the standard astrophysical background. Furthermore, the total antinuclei flux from insterstellar spallation plus SNR-component is tightly bounded by the data, so that hadronic production in SNRs has a minor impact on the astrophysical background for dark matter searches.Comment: 35th International Cosmic Ray Conference - ICRC2017, 10-20 July 2017 - Bexco, Busan, Kore

Creencias de los estudiantes en torno a los Espacios Virtuales de Aprendizaje en el desarrollo de la competencia comunicativa oral. Un estudio de caso

Oral communicative competence is traditionally neglected in the development of competence of students in compulsory education. In a highly demanding social and professional context, we must contribute to communication skills in general and to oral skills in particular. Together with this, given the digital and changing context in which we find ourselves, we need to know and master new means of production and reception of messages mediated by technology. Virtual Learning Environments open up an updated field of work that allows for feedback and the extension of the spatial-temporal limits of the classroom for the development of orality

Understanding and Improving the Cavity Absorptance for Space TSI Radiometers

Total Solar Irradiance (TSI) is the measure of the solar power per unit area, the electromagnetic radiation integrated over the whole electromagnetic spectrum at the top of the atmosphere, normalized to a distance from the Sun of 1 AU (astronomical unit). In order to measure TSI, solar radiometers are utilized. In this work a study of the degradation process that solar radiometers suffer is presented. Among all sources that may produce damage on the receivers, this work is focused on UV radiation. Experimental data was obtained and compared against instruments who suffered degradation during their operative lifetime in space. On the other hand, a next generation of receiver for solar radiometers was designed, studying changes on the coating (by application of the latest discoveries in ultra-black materials), the geometry of the detector (to improve the optical and mechanical properties of the new coatings), and the substitution of components of the instruments (by more recent technologies). The aim of this new generation of absolute radiometers is to obtain more accurate measurements avoiding degradation effects on their coatings. A prototype of this new receiver for solar radiometer was produced and optically characterized. The new coating provides a higher absorptance coefficient than the previous cavity design with glossy paints and no degradation due to UV radiation was found. The Physikalisch- Meteorologisches Observatorium Davos and World Radiation Center (PMOD/WRC) has a record of more than 100 years measuring the sun and a long history of developing radiometers. In 2015, an international team of experts placed the PMOD as one of two world-wide leading institutions in the field of Total Solar Irradiance (TSI) metrology. PMOD/WRC provides very high-quality services to international and national organizations such as the World Meteorological Organization (WMO) and space agencies, in particular the European Space Agency (ESA)

Modeling the gravitational clustering in hierarchical scenarios of structure formation

[spa] En la tesis se presenta un método semianalítico para describir el crecimiento de objetos virializados en el escenario de inestabilidad gravitatoria. Se ha desarrollado el formalismo del sistema confluente de trayectorias, que permite seguir la evolución por filtrado de picos en un campo aleatorio gaussiano de perturbaciones de densidad. Este formalismo es aplicado para deducir la función de masas en el modelo de picos. Después de determinar el filtro (gaussiano) y las relaciones M(R) y SC(T) consistentes con la dinamica de colapso real, se ha encontrado una función de masas, corregida del efecto de nubes encajadas, muy próxima a la de Press y Schechter que ajusta bien los resultados de simulaciones a N-cuerpos. El formalismo del sistema confluente también permite calcular otras cantidades importantes relacionadas con la evolución de objetos virializados, con la ventaja de proporcionar una distinción práctica entre procesos de acreción y fusión. Esto conduce a una definición natural de los sucesos que indican la formación y destrucción de un objeto dado y, por lo tanto, a mejores estimaciones de los ritmos y tiempos típicos de crecimiento. En particular, se han deducido expresiones para los ritmos instantáneos de fusión, captura y formación, el ritmo de acreción de masa, la edad típica y el tiempo de supervivencia

Culminating the Peak Cusp to Descry the Dark Side of Halos

The ConflUent System of Peak trajectories (CUSP) is a rigorous formalism in the framework of the peak theory that allows one to derive from first principles andno free parameters the typical halo properties from the statistics of peaks in the filtered Gaussian random field of density perturbations. The predicted halo mass function, spherically averaged density, velocity dispersion, velocity anisotropy, ellipticity, prolateness and potential profiles, as well as the abundance and number density profiles of accreted and stripped subhalos and diffuse dark matter accurately recover the results of cosmological $N$-body simulations. CUSP is thus a powerful tool for the calculation, in any desired hierarchical cosmology with Gaussian perturbations, of halo properties beyond the mass, redshift and radial ranges covered by simulations. More importantly, CUSP unravels the origin of the characteristic features of those properties. In the present Paper we culminate its construction. We show that all halo properties but those related with subhalo stripping are independent of the assembly history of those objects, and that the Gaussian is the only smoothing window able to find the finite collapsing patches while properly accounting for the entropy increase produced in major mergers

An improved treatment of cosmological intergalactic medium evolution

The modeling of galaxy formation and reionization, two central issues of modern cosmology, relies on the accurate follow-up of the intergalactic medium (IGM). Unfortunately, owing to the complex nature of this medium, the differential equations governing its ionization state and temperature are only approximate. In this paper, we improve these master equations. We derive new expressions for the distinct composite inhomogeneous IGM phases, including all relevant ionizing/recombining and cooling/heating mechanisms, taking into account inflows/outflows into/from halos, and using more accurate recombination coefficients. Furthermore, to better compute the source functions in the equations we provide an analytic procedure for calculating the halo mass function in ionized environments, accounting for the bias due to the ionization state of their environment. Such an improved treatment of IGM evolution is part of a complete realistic model of galaxy formation presented elsewhere