X iv : a st ro - p h / 03 04 41 3 v 2 2 4 A pr 2 00 3 On particle acceleration around shocks . II : on the diffuse scattering by moving media Mario

A pr 2 00 3 On particle acceleration around shocks . II : on the diffuse scattering by moving media Mario

The probability that a particle, crossing the shock along a given direction, be reflected backwards along another direction, was shown to be the key element in determining the spectrum of non–thermal particles accelerated via Fermi mechanism around a shock. Here an explicit equation for this probability distribution is given, for both the upstream and downstream sections. Though analytically in...

ar X iv : a st ro - p h / 02 04 03 6 v 1 2 A pr 2 00 2 Investigating the Flame Microstructure in Type

ar X iv : a st ro - p h / 04 10 41 3 v 1 1 8 O ct 2 00 4 Quantum - Gravity phenomenology and high energy particle propagation

Quantum-gravity effects may introduce relevant consequences for the propagation and interaction of high energy cosmic rays particles. Assuming the space-time foamy structure results in an intrinsic uncertainty of energy and momentum of particles, we show how low energy (under GZK) observations can provide strong constraints on the role of the fluctuating space-time structure.

ar X iv : a st ro - p h / 01 04 11 3 v 1 6 A pr 2 00 1 1 / 2 Law for Non - Radiative Accretion Flow

At low densities, when radiation of an accreting gas is dynamically unimportant, quasi-spherical non-radiative accretion flow is formed around a compact object. We show that the density of the flow is n ∝ r −1/2. The gas compression is much weaker than the standard Bondi's, n ∝ r −3/2 , because most of the gas does not reach the compact object. It can either circulate indefinitely long or it ca...

ar X iv : a st ro - p h / 04 03 54 8 v 1 2 3 M ar 2 00 4 1 2 - 100 KEV SPECTRUM OF AN ACTIVELY STAR FORMING GALAXY

We compute the synthetic 2-100 keV spectrum of an actively star forming galaxy. To this aim we use a luminosity function of point sources appropriate for starbursts (based on Chandra data), as well as the types of stellar sources and their corresponding spectra. Our estimates indicate that a Compton spectral component resulting from scattering of SN-accelerated electrons by ambient FIR and CMB ...