Search results for "COSMIC"
showing 10 items of 656 documents
The EUSO Data Simulation and Analysis Tree
2004
The "Extreme Universe Space Observatory - EUSO" is the first Space mission devoted to the exploration of the outermost bounds of the Universe through the investigation of the Extremely-High Energy Cosmic Rays, EECR, using the Earth atmosphere as a giant detector. The objective is to obtain a detailed description of the Cosmic Ray spectrum beyond 5×1019 eV together with a map of the arrival directions. EUSO will detect EECR looking at the streak of fluorescence light produced when such a particle interacts with the atmosphere. The signal will be detected after its propagation upward from the dark Earth atmosphere to the EUSO telescope accommodated, as external payload, on the International S…
The antares neutrino detector instrumentation
2012
ANTARES is actually the fully operational and the largest neutrino telescope in the Northern hemisphere. Located in the Mediterranean Sea, it consists of a 3D array of 885 photomultiplier tubes (PMTs) arranged in 12 detection lines (25 storeys each), able to detect the Cherenkov light induced by upgoing relativistic muons produced in the interaction of high energy cosmic neutrinos with the detector surroundings. Among its physics goals, the search for neutrino astrophysical sources and the indirect detection of dark matter particles coming from the sun are of particular interest. To reach these goals, good accuracy in track reconstruction is mandatory, so several calibration systems for tim…
Atmospheric Background Measurement in the 300–400 nm Band with a Balloon Borne Experiment during a Nocturnal Flight
2001
The balloon borne experiment, named BABY (BAckground BYpass) belongs to a wider program, AIRWATCH-OWL, intended for the observation of high energy Cosmic Rays from space, detecting the faint UV fluorescence light emitted by the atmospheric Nitrogen as final result of a complex hadronic cascade. In this framework, one of the fundamental information concern the knowledge of the background level. This is one of the main parameters that contribute to the sensitivity of any kind of instrument. The apparatus used for the BABY experiment was designed and completely built at the IFCAI-CNR in Palermo. The instrument is composed by two filtered and collimated photomultipliers (PMT) that detect the UV…
The evolution of the large-scale emission in Fanaroff-Riley type I jets
2011
Recent observations in X-rays and gamma-rays of nearby Fanaroff-Riley type I (FR I) radio galaxies have raised the question of the origin of the emission detected in the termination structures of their jets. The study of these structures can give information on the conditions for particle acceleration and radiation at the front shocks. In addition, an evolutionary scenario can help to disentangle the origin of the detected X-ray emission in young FR I sources, like some gigahertz peaked spectrum active galactic nuclei. This work focuses on the nature and detectability of the radiation seen from the termination regions of evolving FR I jets. We use the results of a relativistic, two-dimensio…
Ray-tracing through N-body simulations and CMB anisotropy estimations
2007
The fully nonlinear evolution of galaxy clusters and substructures –given by N-body simulations– is used to simulate maps of the Rees-Sciama (RS) effect. The universe is covered by simulation boxes and photons move across them. A recent technique for ray-tracing through N-body simulations is described in detail and implemented. It is based on the existence of preferred directions (to move photons through the boxes), and also on the use of an appropriate cutoff. By the moment, only small RS maps (around 2×2) have been obtained with this technique. We justify that our ray-tracing procedure is also appropriate in the case of large simulation cubes (∼ 1000 Mpc per edge), where high enough resol…
Gravitational Waves from an Axion-Dark Photon System: A Lattice Study
2021
In this work, we present a lattice study of an axion - dark photon system in the early Universe and show that the stochastic gravitational wave (GW) background produced by this system may be probed by future GW experiments across a vast range of frequencies. The numerical simulation on the lattice allows us to take into account non-linear backreaction effects and enables us to accurately predict the final relic abundance of the axion or axion-like particle (ALP) as well as its inhomogeneities, and gives a more precise prediction of the GW spectrum. Importantly, we find that the GW spectrum has more power at high momenta due to $2\rightarrow1$ processes. Furthermore, we find the degree of po…
Lens Effect and CMB Anisotropies: Simulations
2003
Cosmological structures deviate the photons of the Cosmic Microwave Background (CMB). The resulting deviations can be calculated moving photons in the gravitational field of realistic lens distributions obtained from numerical simulations. The main goal of this paper is answering the following question: Which types of numerical simulations are appropriate to study angular CMB deformations caused by lensing?
Angular resolution of an array of tracking-chamber detectors for use in high-energy gamma-ray astronomy
1992
We describe a method of analysis for the reconstruction of the arrival direction of a high-energy photon impacting on the top of the atmosphere by using the directions of the particles on the shower front as measured by a ground-based array of tracking chambers uniformly distributed on a square surface; as an example, an array with enclosed surface of (120×120) m2 has been considered. Estimates on the accuracy of reconstruction are given, after application of the method to computer-simulated shower directions as a function of the number of «smapling» detectors and of their accuracy in the measurement of the «local» shower direction.
Spectral energy distribution and generalized Wien's law for photons and cosmic string loops
2014
Physical objects with energy $u_w(l) \sim l^{-3w}$ with $l$ characteristic length and $w$ a dimensionless constant, lead to an equation of state $p=w\rho$, with $p$ the pressure and $\rho$ the energy density. Special entities with thisbproperty are, for instance, photons ($u = hc/l$, with $l$ the wavelength) with $w = 1/3$, and some models of cosmic string loops ($u =(c^4/aG)l$, with $l$ the length of the loop and $a$ a numerical constant), with $w = -1/3$. Here, we discuss some features of the spectral energy distribution of these systems and the corresponding generalization of Wien's law, which in terms of $l$ has the form $Tl_{mp}^{3w}=constant$, being $l_{mp}$ the most probable size of …
A dynamical dark energy model with a given luminosity distance
2011
It is assumed that the current cosmic acceleration is driven by a scalar field, the Lagrangian of which is a function of the kinetic term only, and that the luminosity distance is a given function of the red-shift. Upon comparison with Baryon Acoustic Oscillations (BAOs) and Cosmic Microwave Background (CMB) data the parameters of the models are determined, and then the time evolution of the scalar field is determined by the dynamics using the cosmological equations. We find that the solution is very different than the corresponding solution when the non-relativistic matter is ignored, and that the universe enters the acceleration era at larger red-shift compared to the standard $\Lambda CD…