Some aspects of high-energy particles emission from binary driven hypernovae

We study the creation and propagation of different particles in a BdHN event. We first study the propagation of high-energy protons in the electric and magnetic field near the BH. The electromagnetic field around the BH is described via the solution by R. Wald in 1974. The protons, depending on the relative angle with the fields, lose energy by mean of sychrotron emission and we study the trasparency of the synchrotron photons, considering some processes of particle creation and annihilation. In addition, we study the neutrino emission by proton-proton interaction in three different physical situations occuring in a BdHN event: interactions by low energy, high energy and ultra-high-energy protons with protons, at rest, with different number densities are considered.

On the high energy radiation and its possible origin in GRBs

Semi-analytical models of gravitational wave radiation: binary black holes and chirping stars

Opening remarks

The Transit of Mercury and General Relativity: some technical aspects for the next event

The data used by Le Verrier (Tisserand, 1880) to find the anomalous precession of the perihelion of the orbit of Mercury were the transits of the planet on the Sun available since 1631 (about 13 per century) and the maximum elongations. The Sun is indeed the main reference point for all ground-based measurements, being the sky always bright at 28 of maximum elongation. The knowledge on the solar position was better than 20 already at the time of Tycho Brahe (before 1601) and therefore this is the upper limit of the accuracy of the data calculations on the orbit of Mercury. Here we present a didactic model for the evaluation of the error bars in the calculation of the apsides of Mercury, based on the least square method: 13 data points per century with an errorbar of 20 in ecliptic longitude, per 2.5 centuries yield an accuracy for the apsides 20/sqrt(N) with N=32, enough to detect at 5 sigma the signal of the anomalous precession of the perihelion. From these calculations, Le Verrier found the famous excess of 43 per century out of a total 5500/cy perihelion advance. Such excess was finally explained by Einstein through General Relativity, see Nobili and Will (1986). Not all researchers agreed on such explanation, for instance Dicke and Goldenberg in 1967 made an attempt to measure the quadrupole moment of the Sun; they also provide a database of alternative explanations. After the claim by Eddy and Boornazian (1978) of a larger diameter of the Sun in 1567 during the annular-total eclipse observed by Clavius in Rome (1580), Shapiro (1980) proposed to utilize The observations of the transits of Mercury to monitor the solar diameter variations along the centuries. In this paper, we reconsider the visual observations made before the advent of the photography and electronic devices to identify possible sources of error, starting from the black drop effect. In addition, we discuss other models for the error bars associated to the observations of the transits from the data of Gambart (1832), Sigismondi and Altafi (2016) and Kattendit (2017). The consequences on the solar diameter variations are reconsidered, as above for the apsides. The method that nowadays we use for recovering the variations of the Solar diameter from ground-based observations of Mercury transits is based upon the most recent ephemerides of the Sun and of Mercury (DE406, JPL ; Horizon, NASA and Chapront-Touz, IMCCE), using a standard solar diameter of 1919.26 (Auwers, 1891). The phenomenon of the black drop (Schneider, Pasachoff, Golub, 2004) is considered for the data reduction: the timing of the external and internal contacts is defined as the extrapolation to zero of the length of the chord drawn by the solar limb and the planet's disk. Another problem to be solved is the accuracy of the timing, to approach the 0.01 s absolute accuracy, by using commercial cameras and the ntp web protocol (Anderson, 2018) after the abandon of the radio timing signals by the INRIM. Grouping together instants provided by iphones, smartphones, radio-controlled watches and websites can easily be verified a spread of 1s. Finally the resolution of the instruments needed to observe the transient sodium exosphere of Mercury (Barbieri, 1999; Mangano, et al., 2005; Leblanc, et al. 2009) during the solar transit is discussed, in view of the application to the detection of extrasolar planets atmospheres (Tinetti, 2019).

The Sun of Angelo Secchi in Italian

On Bose-Einstein condensation in relativistic plasma

The phenomenon of Bose-Einstein condensation is traditionally associated with and experimentally verified for low temperatures. We demonstrate out of first principles that for certain initial conditions non-equilibrium plasma at relativistic temperatures of billions of Kelvin undergoes condensation, predicted by Zeldovich and Levich in their seminal work. We determine the necessary conditions for the onset of condensation and discuss the possibilities to observe such a phenomenon in laboratory and astrophysical conditions.

GRB 190114C: most comprehensive portrait of gamma-ray burst

GRB 190114C possesses the most complete features of a GRB ever. For the GRB components, it forms a complete structure from the prompt emission, afterglow to the emergence of supernova. For the energy range, it presents multi-wavelength emissions from radio, millimeter, optical, X-ray, gamma-ray till TeV, more than $30$ satellites and telescopes participate the observation. For the radiation, it has significant thermal and non-thermal photons, its spectrum exhibits wide-range variation. Moreover, it infers a standard evolutional template since it is topologically identical to GRB 130427A on X-ray, gamma-ray and GeV light-curves. And it gives a clear evidence supporting the same origin of MeV and GeV emissions.

Warm Dark Matter and the role of Self-Interactions in halo formation and cosmology

When describing the dark matter haloes surrounding galaxies, models of self gravitating fermions in thermal equilibrium with masses O(10) keV have gained traction in previous years. These particles fall into the category of Warm Dark Matter (WDM), and reconciling halo models in these mass ranges with particle physics models necessitates certain extensions to the DM models. In this talk, I explore the role of self-interacting extensions to WDM and its effects on haloes and cosmology.