arXiv subjects

Douglas Fregolente

Publications and source records attributed to Douglas Fregolente.

6 recordsLinked to original sources

arXiv2011

Searching for curvature pion radiation from protons in strongly magnetized pulsars

By using rather conservative estimates based on the simplest polar cap model, we search the ATNF Pulsar Catalogue for strongly magnetized stars that could accelerate relativistic protons up to the curvature pion production threshold. The best candidate turns out to be the 16 ms pulsar J0537-6910, but the corresponding characteristic parameter $χ=a/m_p$ is yet too small to give origin to observable signals. We show that, for pulsars with period $P\approx 1\,$ms, a surface polar magnetic field $B \approx 10^{12}$G is required in order to induce detectable curvature pion radiation from accelerated protons in the magnetosphere. Some other emission processes are also considered.

astro-ph.HE↗

arXiv2011

Massive particle production from accelerated sources in high magnetic fields

Non-electromagnetic emissions from high energy particles in extreme environments has been studied in the literature by using several variations of the semi-classical formalism. The detailed mechanisms behind such emissions are of great astrophysical interest since they can alter appreciably the associated energy loss rates. Here, we review the role played by the source proper acceleration $a$ in the particle production process. The acceleration $a$ determines the typical scale characterizing the particle production and, moreover, if the massive particle production is inertially forbidden, it will be strongly suppressed for $a$ below a certain threshold. In particular, we show that, for the case of accelerated protons in typical pulsar magnetospheres, the corresponding accelerations $a$ are far below the pion production threshold.

astro-ph.HE↗

arXiv2011

On the particle production threshold for ultra-relativistic accelerated protons

Non-electromagnetic emission from cosmic ray particles accelerated in extreme environments has been studied using different variations of semi-classical formalisms. As the energy loss mechanisms of such particles is of great interest, one must improve in some sense the previously intuitive description of classical sources in the presence of fields. In this brief note we evaluate the role played by the classical and dimensional proper acceleration of a particle in radiation processes. One intends to show that the introduction of the acceleration as a measure parameter gives an adequate scale for considering the processes of massive particle emission. If the acceleration threshold is not attained one is considering a regime where the processes of massive particle production are suppressed. The analysis is performed in a semiclassical formalism once applied in different contexts and already checked for consistency in a serie of papers. As a further application of the results we evaluate the possibility of a non negligible meson production by protons accelerated in the framework of polar cap models operating in electromagnetic fields of pulsars. It is shown that inside a systems endowed with magnetic fields B\geq 10^{12} G the meson emission by protons must not be disregarded.

hep-ph↗

arXiv2008

Lifetime and decay of unstable particles in strong gravitational fields

We consider here the decay of unstable particles in geodesic circular motion around compact objects. For the neutron, in particular, strong and weak decay are calculated by means of a semiclassical approach. Noticeable effects are expected to occur as one approaches the photonic circular orbit of realistic black-holes. We argue that, in such a limit,the quasi-thermal spectrum inherent to extremely relativistic observers in circular motion plays a role similar to the Unruh radiation for uniformly accelerated observers.

gr-qc↗

arXiv2006

Semiclassical approach to the decay of protons in circular motion under the influence of gravitational fields

We investigate the possible decay of protons in geodesic circular motion around neutral compact objects. Weak and strong decay rates and the associated emitted powers are calculated using a semi-classical approach. Our results are discussed with respect to distinct ones in the literature, which consider the decay of accelerated protons in electromagnetic fields. A number of consistency checks are presented along the paper.

gr-qc↗

arXiv2003

Self-interacting dark matter from an SU(3)_L \otimes U(1)_N electroweak model

Recently has been showed that models which consider self-interacting particles as dark matter candidates can be able to account all the discrepancies between N-body simulations and astronomical observations of the galactic structure. In the present work we show that the 3-3-1-electroweak model can provide a realistic candidate to this kind of dark matter. This dark matter particle is not arbitrarily imposed and no new symmetry is need for to stabilize it.

hep-ph↗