32 research outputs found
The Ultraviolet flash accompanying GRBs from neutron-rich internal shocks
In the neutron-rich internal shocks model for Gamma-ray Burts (GRBs), the
Lorentz factors (LFs) of ions shells are variable, so are the LFs of
accompanying neutron shells. For slow neutron shells with a typical LF tens,
the typical beta-decay radius reads R_{\beta,s} several 10^{14} cm, which is
much larger than the typical internal shocks radius 10^{13} cm, so their impact
on the internal shocks may be unimportant. However, as GRBs last long enough
(T_{90}>20(1+z) s), one earlier but slower ejected neutron shell will be swept
successively by later ejected ion shells in the range 10^{13}-10^{15} cm, where
slow neutrons have decayed significantly. We show in this work that ion shells
interacting with the beta-decay products of slow neutron shells can power a
ultraviolet (UV) flash bright to 12th magnitude during the prompt gamma-ray
emission phase or slightly delayed, which can be detected by the upcoming
Satellite SWIFT in the near future.Comment: 6 pages (2 eps figures), accepted for publication in ApJ
Problematic Issues of Qualifying Crimes and Determining the Jurisdiction of Criminal Cases in Relation to Special Subjects: From Practice to Theory
Attention to the effectiveness of modern lawmaking, its prognostic assessments and optimization of law enforcement has not weakened. The consideration of these problems from the point of view of system analysis requires creative interaction of various structures interested in improving state-building, balanced development of the legal system, ensuring the effectiveness of its impact on society, strengthening the rule of law and orderin the country.One of the most effective forms of such coordination is the Scientific and Methodological Council created under the Prosecutor of the Omsk region, a special task among the many of which the development and discussion, together with legal scholars, of scientifically based recommendations on problematic issues of prosecutor’s supervision, legislation and law enforcement practice, legal advisory opinions on issues arising in the practice of prosecutor's supervision.The article proposes to discuss some actual problems of law enforcement raised at one of the meetings of the Scientific and Methodological Council under the Prosecutor of the Omsk region. In particular, the problematic issues of the qualification of actions of persons under Article 165 of the Criminal Code of the Russian Federation (causing property damage by deception or abuse of trust) related to the misuse of funds of resourcesupplying organizations are considered. In this regard, the position is expressed, according to which the process of qualifying a person's actions according to the examined norm requires an analysis of civil law relations.In the second part of the material, the problematic issues of determining the jurisdiction in the proceedings based on the materials of inspections and criminal cases against persons specified in Article 447 of the Code of Criminal Procedure of the Russian Federation, but who have lost their status, are considered. In solving this problem, the actions of Chapter 52 of the Code of Criminal Procedure of the Russian Federation are proposed to be fully extended to the special person specified in it, who at the time of initiating a criminal case lost their official position, but on the condition that the subject of criminal prosecution is a crime committed by one of these persons during the period of their special status. In addition, consideration of other features of criminal proceedings of this type should depend on the specific investigative and judicial situation, and the jurisdiction of criminal cases against “special persons” who have lost their status should be determined according to the general rule of Chapter 52 of the Code of Criminal Procedure of the Russian Federation
Early optical afterglow lightcurves of neutron-fed Gamma-ray bursts
In this paper, within the popular internal shock scenario of GRBs, we
calculate the early optical afterglow lightcurves of a neutron-fed GRB fireball
for different assumed neutron fractions in the fireball and for both ISM- and
wind-interaction models. The cases for both long and short GRBs are considered.
We show that as long as the neutron fraction is significant (e.g. the number of
neutrons is comparable to that of protons), rich afterglow signatures would
show up. For a constant density (ISM) model, a neutron-rich early afterglow is
characterized by a slowly rising lightcurve followed by a sharp re-brightening
bump caused by collision between the leading neutron decay trail ejecta and the
trailing ion ejecta. For a massive star stellar-wind model, the neutron-rich
early afterglow shows an extended plateau lasting for about 100 seconds before
the lightcurve starts to decay. The plateau is mainly attributed to the
emission from the unshocked neutron decay trail. When the overlapping of the
initial prompt rays with the shocks and the trail is important, as is
common for the wind model and is also possible in the ISM model under some
conditions, the IC cooling effect suppresses the very early optical afterglow
significantly, making the neutron-fed signature dimmer. For short GRBs powered
by compact star mergers, a neutron-decay-induced step-like re-brightening is
predicted, although the amplitude is not large. All these neutron-fed
signatures are likely detectable by the Ultraviolet Optical Telescope (UVOT) on
board the {\em Swift} observatory if GRB fireballs are indeed baryonic and
neutron-rich. Close monitoring of early afterglows from 10s to 1000s of
seconds, when combined with detailed theoretical modeling, could be used to
potentially diagnose the existence of the neutron component in GRB fireballs.Comment: 17 pages (6 figures), accepted for publication in ApJ. Several
figures are revised, the IC cooling due to the prompt gamma-rays overlap with
the shocked regions (stellar wind model) has been taken into account. The
possible evidence for the neutron-rich internal shocks (i.e., the prompt
optical and near IR flash accompanying GRB 041219a) has been mentioned
briefl
Some Issues of Terminating a Criminal Case
This publication continues the experience of covering the work of the Scientific and Methodological Council under the Prosecutor of the Omsk Region, among the main tasks of which remains the development and discussion, together with representatives of legal science, of sound recommendations on problematic issues of prosecutorial supervision, legislation and law enforcement practice, legal advisory opinions on issues arising in prosecutorial practice. In this regard, the article proposes to discuss certain topical problems of law enforcement practice raised at one of the last meetings of the Scientific and Methodological Council under the Prosecutor of the Omsk Region. Thus, based on a systematic analysis of errors in the implementation of the institution of a judicial fine, it is proposed to provide prosecutors with systematic supervision over compliance with the requirements of the law when it is applied, which requires a more thorough study of criminal cases, as well as a proper initiative to establish the circumstances associated with the application of a judicial fine, and timely challenging unfounded court decisions. In addition, the practice of law enforcement highlights the fundamental problem of a unified interpretation of the grounds for terminating a criminal case (criminal prosecution) against a person who has committed an act prohibited by criminal law in a state of insanity. Based on the analysis of legal situations and various approaches to their resolution, the article argues for the need to make a decision on the studied criminal cases on the grounds of paragraph 4 of part 1 of Art. 24 of the Criminal Procedure Code of the Russian Federation in connection with the death of a person involved in criminal proceedings. In other similar situations, but related to the criminal prosecution of these persons, the decision must be made taking into account the specific circumstances of the criminal case
Astrophysical implications of hypothetical stable TeV-scale black holes
We analyze macroscopic effects of TeV-scale black holes, such as could
possibly be produced at the LHC, in what is regarded as an extremely
hypothetical scenario in which they are stable and, if trapped inside Earth,
begin to accrete matter. We examine a wide variety of TeV-scale gravity
scenarios, basing the resulting accretion models on first-principles, basic,
and well-tested physical laws. These scenarios fall into two classes, depending
on whether accretion could have any macroscopic effect on the Earth at times
shorter than the Sun's natural lifetime. We argue that cases with such effect
at shorter times than the solar lifetime are ruled out, since in these
scenarios black holes produced by cosmic rays impinging on much denser white
dwarfs and neutron stars would then catalyze their decay on timescales
incompatible with their known lifetimes. We also comment on relevant lifetimes
for astronomical objects that capture primordial black holes. In short, this
study finds no basis for concerns that TeV-scale black holes from the LHC could
pose a risk to Earth on time scales shorter than the Earth's natural lifetime.
Indeed, conservative arguments based on detailed calculations and the
best-available scientific knowledge, including solid astronomical data,
conclude, from multiple perspectives, that there is no risk of any significance
whatsoever from such black holes.Comment: Version2: Minor corrections/fixed typos; updated reference
Beta decay radiation signature from neutron-rich gamma-ray bursts?
Core collapse of massive stars and binary neutron stars or black hole-neutron
star binary mergers are likely progenitors of long and short duration gamma-ray
bursts respectively. Neutronized material in the former and neutron star
material in the latter are ejected by the central engine implying a
neutron-rich jet outflow. A free neutron, however, beta decays to a proton, an
electron (beta) and an anti-neutrino in about fifteen minutes in its rest
frame. Sudden creation of a relativistic electron is accompanied by radiation
with unique temporal and spectral signature. We calculate here this radiation
signature collectively emitted by all beta decay electrons from neutron-rich
outflow. Detection of this signature may thus provide strong evidence for not
only neutron but also for proton content in the relativistic gamma-ray burst
jets.Comment: 11 pages, 2 figures, reference added, published versio
Supernova pointing with low- and high-energy neutrino detectors
A future galactic SN can be located several hours before the optical
explosion through the MeV-neutrino burst, exploiting the directionality of
--scattering in a water Cherenkov detector such as Super-Kamiokande. We
study the statistical efficiency of different methods for extracting the SN
direction and identify a simple approach that is nearly optimal, yet
independent of the exact SN neutrino spectra. We use this method to quantify
the increase in the pointing accuracy by the addition of gadolinium to water,
which tags neutrons from the inverse beta decay background. We also study the
dependence of the pointing accuracy on neutrino mixing scenarios and initial
spectra. We find that in the ``worst case'' scenario the pointing accuracy is
at 95% C.L. in the absence of tagging, which improves to
with a tagging efficiency of 95%. At a megaton detector, this accuracy can be
as good as . A TeV-neutrino burst is also expected to be emitted
contemporaneously with the SN optical explosion, which may locate the SN to
within a few tenths of a degree at a future km high-energy neutrino
telescope. If the SN is not seen in the electromagnetic spectrum, locating it
in the sky through neutrinos is crucial for identifying the Earth matter
effects on SN neutrino oscillations.Comment: 13 pages, 7 figures, Revtex4 format. The final version to be
published in Phys. Rev. D. A few points in the original text are clarifie
Can a Large Neutron Excess Help Solve the Baryon Loading Problem in Gamma-Ray Burst Fireballs?
We point out that the baryon-loading problem in Gamma-Ray Burst (GRB) models
can be amelioriated if a significant fraction of the baryons which inertially
confine the fireball are converted to neutrons. A high neutron fraction in some
circumstances can result in a reduced transfer of energy from relativistic
light particles in the fireball to baryons. The energy needed to produce the
required relativistic flow in the GRB is consequently reduced, in some cases by
orders of magnitude. This could be relevant to GRB models because a high
neutron-to-proton ratio has been calculated in neutron star-merger fireball
environments. Significant neutron excess also could occur near compact objects
with high neutrino fluxes.Comment: 5 pages, 2 figures, to appear in Phys. Rev. Let
Neutron-Rich Freeze-Out in Viscously Spreading Accretion Disks Formed from Compact Object Mergers
Accretion disks with masses ~0.001-0.1 Msun form during the merger of neutron
star (NS)-NS and black hole-NS binaries. Initially, such hyper-accreting disks
cool efficiently by neutrino emission and their composition is driven
neutron-rich by pair captures under degenerate conditions. However, as the disk
viscously spreads and its temperature drops, cooling becomes inefficient and
the disk becomes advective. Analytic arguments and numerical simulations
suggest that once this occurs, powerful winds likely drive away most of the
disk's remaining mass. We calculate the thermal evolution and nuclear
composition of viscously spreading accretion disks formed from compact object
mergers using one-dimensional height-integrated simulations. We show that
freeze-out from weak equilibrium necessarily accompanies the disk's late-time
transition to an advective state. As a result, hyper-accreting disks
generically freeze out neutron-rich (with electron fraction Ye ~ 0.2-0.4), and
their late-time outflows robustly synthesize rare neutron-rich isotopes. Using
the measured abundances of these isotopes in our solar system, we constrain the
compact object merger rate in the Milky Way to be < 1e-5 (M_d,0/0.1 Msun)^(-1)
per year, where M_d,0 is the average initial mass of the accretion disk. Thus,
either the NS-NS merger rate is at the low end of current estimates or the
average disk mass produced during a typical merger is << 0.1 Msun. We also show
that if most short duration gamma-ray bursts (GRBs) are produced by compact
object mergers, their beaming fraction must exceed f_b ~ 0.13(M_d,0/0.1 Msun),
corresponding to a jet half-opening angle > 30(M_d,0/0.1 Msun)^(1/2) degrees.
This is consistent with other evidence that short duration GRB outflows are
less collimated than those produced in long duration GRBs.Comment: 12 pages, 9 figures, 1 table; accepted to MNRAS; minor changes to
text and figure
Gamma-Ray Bursts: The Underlying Model
A pedagogical derivation is presented of the ``fireball'' model of gamma-ray
bursts, according to which the observable effects are due to the dissipation of
the kinetic energy of a relativistically expanding wind, a ``fireball.'' The
main open questions are emphasized, and key afterglow observations, that
provide support for this model, are briefly discussed. The relativistic outflow
is, most likely, driven by the accretion of a fraction of a solar mass onto a
newly born (few) solar mass black hole. The observed radiation is produced once
the plasma has expanded to a scale much larger than that of the underlying
``engine,'' and is therefore largely independent of the details of the
progenitor, whose gravitational collapse leads to fireball formation. Several
progenitor scenarios, and the prospects for discrimination among them using
future observations, are discussed. The production in gamma- ray burst
fireballs of high energy protons and neutrinos, and the implications of burst
neutrino detection by kilometer-scale telescopes under construction, are
briefly discussed.Comment: In "Supernovae and Gamma Ray Bursters", ed. K. W. Weiler, Lecture
Notes in Physics, Springer-Verlag (in press); 26 pages, 2 figure