scholarly journals Systematic parameter space study for the UHECR origin from GRBs in models with multiple internal shocks

2020 ◽  
Vol 498 (4) ◽  
pp. 5990-6004 ◽  
Author(s):  
J Heinze ◽  
D Biehl ◽  
A Fedynitch ◽  
D Boncioli ◽  
A Rudolph ◽  
...  
Keyword(s):  
Parameter Space ◽  
Gamma Ray ◽  
Ultrahigh Energy ◽  
Long Duration ◽  
Internal Shock ◽  
Wide Range ◽  
Multiple Collisions ◽  
To Come ◽  
Neutrino Fluxes ◽  
Comparable Quality

ABSTRACT We scrutinize the paradigm that conventional long-duration gamma-ray bursts (GRBs) are the dominant source of the ultrahigh energy cosmic rays (UHECRs) within the internal shock scenario by describing UHECR spectrum and composition and by studying the predicted (source and cosmogenic) neutrino fluxes. Since it has been demonstrated that the stacking searches for astrophysical GRB neutrinos strongly constrain the parameter space in single-zone models, we focus on the dynamics of multiple collisions for which different messengers are expected to come from different regions of the same object. We propose a model that can describe both stochastic and deterministic engines, which we study in a systematic way. We find that GRBs can indeed describe the UHECRs for a wide range of different model assumptions with comparable quality albeit with the previously known problematic energy requirements; the heavy mass fraction at injection is found to be larger than 70 per cent ($95 {{\ \rm per\ cent}}$ CL). We demonstrate that the post-dicted (from UHECR data) neutrino fluxes from sources and UHECR propagation are indeed below the current sensitivities but will be reached by the next generation of experiments. We finally critically review the required source energetics with the specific examples found in this study.

Gamma-ray bursts prompt emission spectrum: an analysis of a photosphere model

2007 ◽  
Vol 365 (1854) ◽  
pp. 1171-1175 ◽  
Author(s):  
Asaf Pe'er ◽  
Peter Mészáros ◽  
Martin J Rees
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Dissipation Process ◽  
Internal Shock ◽  
Peak Energy ◽  
Wide Range ◽  
Low Energies ◽  
Steep Slopes ◽  
The Magnetic Field ◽  
Prompt Emission

A thermal radiative component is likely to accompany the first stages of the prompt emission of gamma-ray bursts (GRBs) and X-ray flashes. We analyse the effect of such a component on the observable spectrum, assuming that the observable effects are due to a dissipation process occurring below or near the thermal photosphere. For comparable energy densities in the thermal and leptonic components, the dominant emission mechanism is Compton scattering. This leads to a nearly flat energy spectrum ( νF ν ∝ ν 0 ) above the thermal peak at approximately 10–100 keV and below 10–100 MeV, for a wide range of optical depths 0.03≲ τ ≲100, regardless of the details of the dissipation mechanism or the strength of the magnetic field. For higher values of the optical depth, a Wien peak is formed at 100 keV to 1 MeV. In particular, these results are applicable to the internal shock model of GRBs, as well as to slow dissipation models, e.g. as might be expected from reconnection, if the dissipation occurs at a sub-photospheric radii. We conclude that dissipation near the thermal photosphere can naturally explain (i) clustering of the peak energy at sub-MeV energies at early times, (ii) steep slopes observed at low energies, and (iii) a flat spectrum above 10 keV at late times. Our model thus provides an alternative scenario to the optically thin synchrotron–synchrotron self-Compton model.

scholarly journals A roadmap to hadronic supercriticalities: a comprehensive study of the parameter space for high-energy astrophysical sources

2020 ◽  
Vol 495 (2) ◽  
pp. 2458-2474
Author(s):  
Apostolos Mastichiadis ◽  
Ioulia Florou ◽  
Elina Kefala ◽  
Stella S Boula ◽  
Maria Petropoulou
Keyword(s):  
Parameter Space ◽  
Proton Energy ◽  
Gamma Ray ◽  
Source Parameters ◽  
High Energy ◽  
Linear Dynamical Systems ◽  
Relativistic Plasmas ◽  
Electron Positron ◽  
Wide Range ◽  
Comprehensive Study

ABSTRACT Hadronic supercriticalities are radiative instabilities that appear when large amounts of energy are stored in relativistic protons. When the proton energy density exceeds some critical value, a runaway process is initiated resulting in the explosive transfer of the proton energy into electron–positron pairs and radiation. The runaway also leads to an increase of the radiative efficiency, namely the ratio of the photon luminosity to the injected proton luminosity. We perform a comprehensive study of the parameter space by investigating the onset of hadronic supercriticalities for a wide range of source parameters (i.e. magnetic field strengths of 1 G−100 kG and radii of 1011−1016 cm) and maximum proton Lorentz factors (103−109). We show that supercriticalities are possible for the whole range of source parameters related to compact astrophysical sources, like gamma-ray bursts and cores and jets of active galactic nuclei. We also provide an in-depth look at the physical mechanisms of hadronic supercriticalities and show that magnetized relativistic plasmas are excellent examples of non-linear dynamical systems in high-energy astrophysics.

scholarly journals Ultrahigh energy neutrino afterglows of nearby long duration gamma-ray bursts

2017 ◽  
Vol 96 (10) ◽  
Author(s):  
Jessymol K. Thomas ◽  
Reetanjali Moharana ◽  
Soebur Razzaque
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Ultrahigh Energy ◽  
Energy Neutrino ◽  
Long Duration

scholarly journals Modeling the ISM Properties of Metal-Poor Galaxies and Gamma-Ray Burst Hosts

2008 ◽  
Vol 4 (S255) ◽  
pp. 162-166 ◽  
Author(s):  
Emily M. Levesque ◽  
Lisa J. Kewley ◽  
Kirsten Larson ◽  
Leonie Snijders
Keyword(s):  
Gamma Ray ◽  
Optical Emission ◽  
Physical Parameters ◽  
Exact Nature ◽  
Population Synthesis ◽  
Host Galaxies ◽  
Long Duration ◽  
Wide Range ◽  
Low Metallicity ◽  
Galaxy Populations

AbstractRecent research has suggested that long-duration gamma-ray bursts (LGRBs) occur preferentially in low-metallicity environments, but the exact nature of this correlation is currently a matter of intense debate. We use the newest generation of the Starburst99/Mappings code to generate an extensive suite of cutting-edge stellar population synthesis models, covering a wide range of physical parameters specifically tailored for modeling the ISM environments of metal-poor galaxies and LGRB host galaxies. With our models, we generate optical emission line diagnostics, which will allow us to examine the ISM properties and stellar populations of a variety of galaxy populations in unprecedented detail. While accurately modeling low-metallicity galaxies still poses a challenge to these models, future improvements to these grids will have profound consequences for our understanding of metal-poor galaxies, their ISM environments, and the nature of their role as the hosts of LGRBs.

Knowledge assessment and barriers to cancer screening among Ghanaian community pharmacists

2021 ◽  
pp. 107815522098341
Author(s):  
Kofi B Mensah ◽  
Adwoa Bemah Boamah Mensah ◽  
Peter Yamoah ◽  
Joseph Attakorah ◽  
Varsha Bangalee ◽  
...  
Keyword(s):  
Cancer Screening ◽  
Reliability And Validity ◽  
Community Pharmacists ◽  
Online Questionnaire ◽  
Screening Guidelines ◽  
Validity Assessment ◽  
Wide Range ◽  
Chi Squared ◽  
Primary Healthcare Provider ◽  
To Come

Introduction Though there are controversies, cancer screening has been suggested to decrease mortality. Over the years, the most accessible primary healthcare provider; the community pharmacist, has developed an interest in being part of cancer screening activities and prevention of a wide range of other non-communicable diseases. To achieve this, community pharmacists need a working knowledge of the basic screening test and recommendations. Also, it’s important to acknowledge the barriers that may prevent the implementation of cancer-screening efforts at the community pharmacy. This study aims to determine the knowledge and barriers to cancer screening among Ghanaian community pharmacists. Methodology Knowledge and barriers to cancer screening was assessed using an online questionnaire in 435 community pharmacists. Descriptive statistics and Pearson's chi-squared tests were used to analyze the data. Results The reliability and validity assessment of the questionnaire after data collection revealed a Cronbach’s alpha value of 0.82 for knowledge on cancer screening. The SD and mean age of study participants were 2.48 ± 20.08. Only 25.7% of the participants had good knowledge. The most identified barrier was the lack of established guidelines (60.9%). There was no association between participants' demographics and their knowledge scores. Conclusions Community pharmacists can potentially have a large impact on early detection of cancer through screening. However, they have to improve their knowledge on general screening guidelines and be aware of available educational resources to increase their knowledge. It is also important for all stakeholders to come together to establish local screening modalities and recommendations for the country.

A Wide Range Ge Gamma-Ray Spectrometer for on-Line Measurements of Reactor Cooling Water Activity

1977 ◽  
Vol 24 (1) ◽  
pp. 673-677 ◽  
Author(s):  
J. J. Lipsett ◽  
I. L. Fowler ◽  
R. J. Dinger ◽  
H. L. Malm
Keyword(s):  
Water Activity ◽  
Gamma Ray ◽  
Cooling Water ◽  
Gamma Ray Spectrometer ◽  
Wide Range ◽  
On Line

Measurement of pulmonary edema in intact dogs by transthoracic gamma-ray attenuation

1979 ◽  
Vol 47 (6) ◽  
pp. 1228-1233 ◽  
Author(s):  
D. S. Simon ◽  
J. F. Murray ◽  
N. C. Staub
Keyword(s):  
Pulmonary Edema ◽  
Time Course ◽  
Gamma Ray ◽  
High Sensitivity ◽  
Lung Edema ◽  
Lung Water ◽  
Vascular Congestion ◽  
Isolated Lung ◽  
Wide Range ◽  
Gamma Ray Attenuation

We evaluated the attenuation of the 122 keV gamma ray of cobalt-57 across the thorax of anesthetized dogs as a method for following the time course of lung water changes in acute pulmonary edema induced by either increased microvascular permeability or increased microvascular hydrostatic pressure. The gamma rays traversed the thorax centered on the seventh rib laterally where the lung mass in the beam path was greatest. Calibration measurements in isolated lung lobes demonstrated the high sensitivity and inherent accuracy of the method over a wide range of lung water contents. In control dogs reproducibility averaged +/-3%. Increased permeability edema led to large rapid increases in the transthoracic gamma ray attenuation (TGA), while increased pressure caused an immediate, modest increase in TGA (vascular congestion) followed by a slow further increase over 2 h. There was a fairly good correlation between the increase in extravascular lung water and the change in TGA. The method is simple, safe, and noninvasive and appears to be useful for following the time course of lung water accumulation in generalized lung edema in anesthetized animals.

The 1972 Elections

1973 ◽  
Vol 7 (1) ◽  
pp. 1-15
Author(s):  
H. G. Nicholas
Keyword(s):  
Political Parties ◽  
Data Gathering ◽  
The United States ◽  
United States Constitution ◽  
The Public ◽  
Pressure Groups ◽  
Wide Range ◽  
Political Forces ◽  
American Elections ◽  
To Come

Elections satisfy both the practical and the theoretical requirements of classical democratic theory if they answer one question only: Who shall rule? Judged by this test the American elections of 7 November 1972 returned as clear and unequivocal an answer as the United States Constitution permits – crystal-clear as to individuals, equivocal as to parties and political forces. But the student of politics and society cannot resist treating elections as data-gathering devices on a wide range of other questions, on the state of the public mind, on the relative potency of pressure groups, on the internal health of the political parties, and, of course, on the shape of things to come. In this ancillary role American elections, despite the generous wealth of statistical material which they throw up – so much more detailed and categorized (though often less precise) than our own – Suffer in most years from one severe limitation, a limitation which in 1972 was particularly conspicuous; they do not engage the interest of more than a moderate percentage of the American citizenry. In 1972 that percentage was as low as 55 per cent, i.e. out of an estimated eligible population of 139,642,000 only 77,000,000 went to the polls. Since this circumscribes the conclusions which can be drawn from the results themselves, as well as constituting a phenomenon of considerable intrinsic interest, it seems worthwhile to begin any examination of the 1972 elections by an analysis not of the votes counted but of those which were never cast.

scholarly journals CAN STELLAR MIXING EXPLAIN THE LACK OF TYPE Ib SUPERNOVAE IN LONG-DURATION GAMMA-RAY BURSTS?

2013 ◽  
Vol 773 (1) ◽  
pp. L7 ◽  
Author(s):  
Lucille H. Frey ◽  
Chris L. Fryer ◽  
Patrick A. Young
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Long Duration

ECCENTRIC, GIFTED, AND BLACK: THELONIOUS MONK REVEALED

2010 ◽  
Vol 7 (2) ◽  
pp. 381-402
Author(s):  
Ingrid Monson ◽  
John Gennari ◽  
Travis A. Jackson
Keyword(s):  
Primary Research ◽  
Thelonious Monk ◽  
Wide Range ◽  
American Composer ◽  
Personal Archives ◽  
To Come ◽  
The Right ◽  
First Time

Do not miss Robin D. G. Kelley's Thelonious Monk: The Life and Times of an American Original, for it will stand as the definitive biography of the great American composer and pianist for many years to come. What distinguishes Kelley's treatment of Monk's complicated and enigmatic life is the sheer depth and breadth of primary research, including, for the first time, the active cooperation and involvement of Thelonious Monk's family. In his acknowledgments, Kelley describes a long process of convincing Thelonious Monk, III to grant permission culminating in a six-hour meeting in which his knowledge, credentials, and commitment were thoroughly tested and challenged. Once he had secured “Toot's” blessings, as well as that of his wife Gale and brother-in-law Peter Grain, Kelley was introduced to Nellie Monk, Thelonious Monk's wife, and a wide range of family and friends who shared their memories and personal archives of photos, recordings, and papers. This is not an authorized biography, however, since Thelonious Monk, Jr. never demanded the right to see drafts or dictate the content. Rather Kelley was admonished to “dig deep and tell the truth.”

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