Douglas Fregolente | UFCG - Universidade Federal de Campina Grande (original) (raw)

Papers by Douglas Fregolente

Research paper thumbnail of Meson synchrotron radiation threshold for ultra-high energy cosmic ray protons: Work in progress

Research paper thumbnail of Meson synchrotron radiation threshold for ultra-high energy cosmic ray protons

Research paper thumbnail of On the particle production threshold for ultra-relativistic accelerated protons

Research paper thumbnail of Gauge model for self interacting dark matter

We show that the called 3-3-1 electroweak model can provide a candidate for self interacting dark... more We show that the called 3-3-1 electroweak model can provide a candidate for self interacting dark matter. This dark matter particle is not arbitrarily imposed in the model and no new symmetry is needed to stabilize it.

Research paper thumbnail of Massive particle production from accelerated sources in high magnetic fields

Non-electromagnetic emissions from high energy particles in extreme environments has been studied... more 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 aaa in the particle production process. The acceleration aaa determines the typical scale characterizing the particle production and, moreover, if the massive particle production is inertially forbidden, it will be strongly suppressed for aaa below a certain threshold. In particular, we show that, for the case of accelerated protons in typical pulsar magnetospheres, the corresponding accelerations aaa are far below the pion production threshold.

Research paper thumbnail of Decay of Accelerated Protons and High Energy Astrophysics

The possible relevance of the decay of accelerated protons in the context of high energy astrophy... more The possible relevance of the decay of accelerated protons in the context of high energy astrophysics is discussed.

Research paper thumbnail of Self-interacting dark matter from a SU(3) L ⊗U(1) N electroweak model

Physics Letters B, 2003

Recently it has been shown that models which consider self-interacting particles as dark matter c... more Recently it has been shown that models which consider self-interacting particles as dark matter candidates can be able to account with practically all the discrepancies between N-body simulations and astronomical observations of the galactic structure. In the present Letter 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 needed to stabilize it.

Research paper thumbnail of Lifetime and decay of unstable particles in strong gravitational fields

Physical Review D, 2008

We consider here the decay of unstable particles in geodesic circular motion around compact objec... more 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.

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

Physical Review D, 2006

We investigate the possible decay of protons in geodesic circular motion around neutral compact o... more 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.

Research paper thumbnail of Searching for curvature pion radiation from protons in strongly magnetized pulsars

Astrophysics and Space Science, 2011

By using rather conservative estimates based on the simplest polar cap model, we search the ATNF ... more 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 chi=a/mp\chi=a/m_pchi=a/mp is yet too small to give origin to observable signals. We show that, for pulsars with period Papprox1,P\approx 1\,Papprox1,ms, a surface polar magnetic field Bapprox1012B \approx 10^{12}Bapprox1012G is required in order to induce detectable curvature pion radiation from accelerated protons in the magnetosphere. Some other emission processes are also considered.

Research paper thumbnail of Meson synchrotron radiation threshold for ultra-high energy cosmic ray protons: Work in progress

Research paper thumbnail of Meson synchrotron radiation threshold for ultra-high energy cosmic ray protons

Research paper thumbnail of On the particle production threshold for ultra-relativistic accelerated protons

Research paper thumbnail of Gauge model for self interacting dark matter

We show that the called 3-3-1 electroweak model can provide a candidate for self interacting dark... more We show that the called 3-3-1 electroweak model can provide a candidate for self interacting dark matter. This dark matter particle is not arbitrarily imposed in the model and no new symmetry is needed to stabilize it.

Research paper thumbnail of Massive particle production from accelerated sources in high magnetic fields

Non-electromagnetic emissions from high energy particles in extreme environments has been studied... more 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 aaa in the particle production process. The acceleration aaa determines the typical scale characterizing the particle production and, moreover, if the massive particle production is inertially forbidden, it will be strongly suppressed for aaa below a certain threshold. In particular, we show that, for the case of accelerated protons in typical pulsar magnetospheres, the corresponding accelerations aaa are far below the pion production threshold.

Research paper thumbnail of Decay of Accelerated Protons and High Energy Astrophysics

The possible relevance of the decay of accelerated protons in the context of high energy astrophy... more The possible relevance of the decay of accelerated protons in the context of high energy astrophysics is discussed.

Research paper thumbnail of Self-interacting dark matter from a SU(3) L ⊗U(1) N electroweak model

Physics Letters B, 2003

Recently it has been shown that models which consider self-interacting particles as dark matter c... more Recently it has been shown that models which consider self-interacting particles as dark matter candidates can be able to account with practically all the discrepancies between N-body simulations and astronomical observations of the galactic structure. In the present Letter 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 needed to stabilize it.

Research paper thumbnail of Lifetime and decay of unstable particles in strong gravitational fields

Physical Review D, 2008

We consider here the decay of unstable particles in geodesic circular motion around compact objec... more 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.

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

Physical Review D, 2006

We investigate the possible decay of protons in geodesic circular motion around neutral compact o... more 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.

Research paper thumbnail of Searching for curvature pion radiation from protons in strongly magnetized pulsars

Astrophysics and Space Science, 2011

By using rather conservative estimates based on the simplest polar cap model, we search the ATNF ... more 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 chi=a/mp\chi=a/m_pchi=a/mp is yet too small to give origin to observable signals. We show that, for pulsars with period Papprox1,P\approx 1\,Papprox1,ms, a surface polar magnetic field Bapprox1012B \approx 10^{12}Bapprox1012G is required in order to induce detectable curvature pion radiation from accelerated protons in the magnetosphere. Some other emission processes are also considered.