236 research outputs found
On the physical processes which lie at the bases of time variability of GRBs
The relative-space-time-transformation (RSTT) paradigm and the interpretation
of the burst-structure (IBS) paradigm are applied to probe the origin of the
time variability of GRBs. Again GRB 991216 is used as a prototypical case,
thanks to the precise data from the CGRO, RXTE and Chandra satellites. It is
found that with the exception of the relatively inconspicuous but
scientifically very important signal originating from the initial ``proper
gamma ray burst'' (P-GRB), all the other spikes and time variabilities can be
explained by the interaction of the accelerated-baryonic-matter pulse with
inhomogeneities in the interstellar matter. This can be demonstrated by using
the RSTT paradigm as well as the IBS paradigm, to trace a typical spike
observed in arrival time back to the corresponding one in the laboratory time.
Using these paradigms, the identification of the physical nature of the time
variablity of the GRBs can be made most convincingly. It is made explicit the
dependence of a) the intensities of the afterglow, b) the spikes amplitude and
c) the actual time structure on the Lorentz gamma factor of the
accelerated-baryonic-matter pulse. In principle it is possible to read off from
the spike structure the detailed density contrast of the interstellar medium in
the host galaxy, even at very high redshift.Comment: 11 pages, 5 figure
The EMBH model in GRB 991216 and GRB 980425
This is a summary of the two talks presented at the Rome GRB meeting by C.L.
Bianco and R. Ruffini. It is shown that by respecting the Relative Space-Time
Transformation (RSTT) paradigm and the Interpretation of the Burst Structure
(IBS) paradigm, important inferences are possible: a) in the new physics
occurring in the energy sources of GRBs, b) on the structure of the bursts and
c) on the composition of the interstellar matter surrounding the source.Comment: 8 pages, 3 figures, in the Proceedings of the "Third Rome Workshop on
Gamma-Ray Bursts in the Afterglow Era", 17-20 September 2002, M. Feroci, F.
Frontera, N. Masetti, L. Piro (editors
The Space Environment and Atmospheric Joule Heating of the Habitable Zone Exoplanet TOI700-d
We investigate the space environment conditions near the Earth-size planet
TOI~700~d using a set of numerical models for the stellar corona and wind, the
planetary magnetosphere, and the planetary ionosphere. We drive our simulations
using a scaled-down stellar input and a scaled-up solar input in order to
obtain two independent solutions. We find that for the particular parameters
used in our study, the stellar wind conditions near the planet are not very
extreme -- slightly stronger than that near the Earth in terms of the stellar
wind ram pressure and the intensity of the interplanetary magnetic field. Thus,
the space environment near TOI700-d may not be extremely harmful to the
planetary atmosphere, assuming the planet resembles the Earth. Nevertheless, we
stress that the stellar input parameters and the actual planetary parameters
are unconstrained, and different parameters may result in a much greater effect
on the atmosphere of TOI700-d. Finally, we compare our results to solar wind
measurements in the solar system and stress that modest stellar wind conditions
may not guarantee atmospheric retention of exoplanets.Comment: accepted to Ap
GRB 970228 Within the EMBH Model
We consider the gamma-ray burst of 1997 February 28 (GRB 970228) within the
ElectroMagnetic Black Hole (EMBH) model. We first determine the value of the
two free parameters that characterize energetically the GRB phenomenon in the
EMBH model, that is to say the dyadosphere energy,
ergs, and the baryonic remnant mass in units of ,
. Having in this way estimated the
energy emitted during the beam-target phase, we evaluate the role of the
InterStellar Medium (ISM) number density (n) and of the ratio between the effective emitting area and the total surface area of the GRB
source, in reproducing the observed profiles of the GRB 970228 prompt emission
and X-ray (2-10 keV energy band) afterglow. The importance of the ISM
distribution three-dimensional treatment around the central black hole is also
stressed in this analysis.Comment: 4 pages, 1 figure, to appear in the Proceedings of the Los Alamos
"Gamma Ray Burst Symposium" in Santa Fe, New Mexico, September 8-12 2003 (AIP
Conf. Ser.), CHAPTER: GRB Connection to Supernova
Stellar Energetic Particle Transport in the Turbulent and CME-disrupted Stellar Wind of AU~Microscopii
Energetic particles emitted by active stars are likely to propagate in
astrospheric magnetized plasma turbulent and disrupted by the prior passage of
energetic Coronal Mass Ejections (CMEs). We carried out test-particle
simulations of GeV protons produced at a variety of distances from the
M1Ve star AU~Microscopii by coronal flares or travelling shocks. Particles are
propagated within the large-scale quiescent three-dimensional magnetic field
and stellar wind reconstructed from measured magnetograms, and { within the
same stellar environment following passage of a ~erg kinetic energy
CME}. In both cases, magnetic fluctuations with an isotropic power spectrum are
overlayed onto the large scale stellar magnetic field and particle propagation
out to the two innnermost confirmed planets is examined. In the quiescent case,
the magnetic field concentrates the particles onto two regions near the
ecliptic plane. After the passage of the CME, the closed field lines remain
inflated and the re-shuffled magnetic field remains highly compressed,
shrinking the scattering mean free path of the particles. In the direction of
propagation of the CME-lobes the subsequent EP flux is suppressed. Even for a
CME front propagating out of the ecliptic plane, the EP flux along the
planetary orbits highly fluctuates and peaks at orders of magnitude
higher than the average solar value at Earth, both in the quiescent and the
post-CME cases.Comment: 19 pages, 14 figures, submitte
On the structures in the afterglow peak emission of gamma ray bursts
Using GRB 991216 as a prototype, it is shown that the intensity substructures observed in what is generally called the "prompt emission" in gamma ray bursts (GRBs) do originate in the collision between the accelerated baryonic matter (ABM) pulse with inhomogeneities in the interstellar medium (ISM). The initial phase of such process occurs at a Lorentz factor . The crossing of ISM inhomogeneities of sizes cm occurs in a detector arrival time interval of s implying an apparent superluminal behavior of . The long lasting debate between the validity of the external shock model vs. the internal shock model for GRBs is solved in favor of the first
New perspectives in physics and astrophysics from the theoretical understanding of Gamma-Ray Bursts
If due attention is given in formulating the basic equations for the
Gamma-Ray Burst (GRB) phenomenon and in performing the corresponding
quantitative analysis, GRBs open a main avenue of inquiring on totally new
physical and astrophysical regimes. This program is one of the greatest
computational efforts in physics and astrophysics and cannot be actuated using
shortcuts. A systematic approach has been highlighted in three paradigms: the
relative space-time transformation (RSTT) paradigm, the interpretation of the
burst structure (IBS) paradigm, the GRB-supernova time sequence (GSTS)
paradigm. In fundamental physics new regimes are explored: (1) the process of
energy extraction from black holes; (2) the quantum and general relativistic
effects of matter-antimatter creation near the black hole horizon; (3) the
physics of ultrarelativisitc shock waves with Lorentz gamma factor . In astronomy and astrophysics also new regimes are explored: (i) the
occurrence of gravitational collapse to a black hole from a critical mass core
of mass M\agt 10M_\odot, which clearly differs from the values of the
critical mass encountered in the study of stars ``catalyzed at the endpoint of
thermonuclear evolution" (white dwarfs and neutron stars); (ii) the extremely
high efficiency of the spherical collapse to a black hole, where almost 99.99%
of the core mass collapses leaving negligible remnant; (iii) the necessity of
developing a fine tuning in the final phases of thermonuclear evolution of the
stars, both for the star collapsing to the black hole and the surrounding ones,
in order to explain the possible occurrence of the "induced gravitational
collapse". A new class of space missions to acquire information on such extreme
new regimes are urgently needed.Comment: RevTeX4, 93 pages, 50 figures, to appear in the "Proceedings of the
Xth Brazilian School of Cosmology and Gravitation", M. Novello, editor, AIP,
in pres
Chirality effects on the IRMPD spectra of basket resorcinarene/nucleoside complexes
The IRMPD spectra of the
ESI-formed proton-bound complexes
of the R,R,R,R- and S,S,S,S-enantiomers
of a bis(diamido)-bridged basket
resorcin[4]arene (R and S) with cytosine
(1), cytidine (2), and cytarabine
(3) were measured in the region 2800–
3600 cm1. Comparison of the IRMPD
spectra with the corresponding
ONIOM (B3LYP/6-31(d):UFF)-calculated
absorption frequencies allowed
the assessment of the vibrational
modes that are responsible for the observed
spectroscopic features. All of
the complexes investigated, apart from
[R·H·3]+, showed similar IRMPD spectra,
which points to similar structural
and conformational landscapes. Their
IRMPD spectra agree with the formation
of several isomeric structures in
the ESI source, wherein the N(3)-protonated
guest establishes noncovalent
interactions with the host amidocarbonyl
groups that are either oriented
inside the host cavity or outside it between
one of the bridged side-chains
and the upper aromatic nucleus. The
IRMPD spectrum of the [R·H·3]+ complex
was clearly different from the
others. This difference is attributed to the effect of intramolecular hydrogen bonding interactions between the
C(2’)-OH group and the aglycone oxygen atom of the nucleosidic guest upon repulsive interactions between
the same oxygen atom and the aromatic rings of the host
A New Astrophysical "Triptych": GRB030329/SN2003dh/URCA-2
We analyze the data of the Gamma-Ray Burst/Supernova GRB030329/SN2003dh
system obtained by HETE-2 (GCN [1]), R-XTE (GCN [2]), XMM (Tiengo et al. [3])
and VLT (Hjorth et al. [4]) within our theory (Ruffini et al. [5] and
references therein) for GRB030329. By fitting the only three free parameters of
the EMBH theory, we obtain the luminosity in fixed energy bands for the prompt
emission and the afterglow (see Fig.1). Since the Gamma-Ray Burst (GRB)
analysis is consistent with a spherically symmetric expansion, the energy of
GRB030329 is E = 2.1 * 10^{52} erg, namely ~ 2 * 10^3 times larger than the
Supernova energy. We conclude that either the GRB is triggering an
induced-supernova event or both the GRB and the Supernova are triggered by the
same relativistic process. In no way the GRB can be originated from the
supernova. We also evidence that the XMM observations (Tiengo et al. [3]), much
like in the system GRB980425/SN1998bw (Ruffini et al. [6], Pian et al. [7]),
are not part of the GRB afterglow, as interpreted in the literature (Tiengo et
al. [3]), but are associated to the Supernova phenomenon. A dedicated campaign
of observations is needed to confirm the nature of this XMM source as a newly
born neutron star cooling by generalized URCA processes.Comment: 4 pages, 1 figure, to appear in the Proceedings of the Los Alamos
"Gamma Ray Burst Symposium" in Santa Fe, New Mexico, September 8-12 2003 (AIP
Conf. Ser.), CHAPTER: GRB03032
Stellar energetic particles in the magnetically turbulent habitable zones of TRAPPIST-1-like planetary systems
Planets in close proximity to their parent star, such as those in the
habitable zones around M dwarfs, could be subject to particularly high doses of
particle radiation. We have carried out test-particle simulations of ~GeV
protons to investigate the propagation of energetic particles accelerated by
flares or travelling shock waves within the stellar wind and magnetic field of
a TRAPPIST-1-like system. Turbulence was simulated with small-scale
magnetostatic perturbations with an isotropic power spectrum. We find that only
a few percent of particles injected within half a stellar radius from the
stellar surface escape, and that the escaping fraction increases strongly with
increasing injection radius. Escaping particles are increasingly deflected and
focused by the ambient spiralling magnetic field as the superimposed turbulence
amplitude is increased. In our TRAPPIST-1-like simulations, regardless of the
angular region of injection, particles are strongly focused onto two caps
within the fast wind regions and centered on the equatorial planetary orbital
plane. Based on a scaling relation between far-UV emission and energetic
protons for solar flares applied to M dwarfs, the innermost putative habitable
planet, TRAPPIST-1e, is bombarded by a proton flux up to 6 orders of magnitude
larger than experienced by the present-day Earth. We note two mechanisms that
could strongly limit EP fluxes from active stars: EPs from flares are contained
by the stellar magnetic field; and potential CMEs that might generate EPs at
larger distances also fail to escape.Comment: 17 pages, 12 figures, ApJ in pres
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