Comparing different energy partitions at scission used in prompt emission model codes GEF and Point-by-Point

2015 ◽  
Vol 940 ◽  
pp. 242-263 ◽  
Author(s):  
A. Tudora ◽  
F.-J. Hambsch ◽  
I. Visan ◽  
G. Giubega
Keyword(s):  
Emission Model ◽  
Prompt Emission

scholarly journals Explaining GRB prompt emission with sub-photospheric dissipation and Comptonization

2019 ◽  
Author(s):  
Mukul Bhattacharya ◽  
Pawan Kumar
Keyword(s):  
Energy Content ◽  
Lorentz Factor ◽  
Photon Spectrum ◽  
Emission Model ◽  
Electron Number ◽  
Radiation Mechanism ◽  
Radiative Efficiency ◽  
Number Ratio ◽  
Sufficient Energy ◽  
Prompt Emission

Abstract Even though the observed spectra for GRB prompt emission is well constrained, no single radiation mechanism can robustly explain its distinct non-thermal nature. Here we explore the radiation mechanism with the photospheric emission model using our Monte Carlo Radiative Transfer (MCRaT) code. We study the sub-photospheric Comptonization of fast cooled synchrotron photons while the Maxwellian electrons and mono-energetic protons are accelerated to relativistic energies by repeated dissipation events. Unlike previous simulations, we implement a realistic photon to electron number ratio Nγ/Ne ∼ 105 consistent with the observed radiative efficiency of a few percent. We show that it is necessary to have a critical number of episodic energy injection events Nrh, cr ∼ few 10s − 100 in the jet in addition to the electron-proton Coulomb coupling in order to inject sufficient energy Einj, cr ∼ 2500 − 4000 mec2 per electron and produce an output photon spectrum consistent with observations. The observed GRB spectrum can be generated when the electrons are repeatedly accelerated to highly relativistic energies γe, in ∼ few 10s − 100 in a jet with bulk Lorentz factor Γ ∼ 30 − 100, starting out from moderate optical depths τin ∼ 20 − 40. The shape of the photon spectrum is independent of the initial photon energy distribution and baryonic energy content of the jet and hence independent of the emission mechanism, as expected for photospheric emission.

scholarly journals A Backscattering-dominated Prompt Emission Model for the Prompt Phase of Gamma-Ray Bursts

2021 ◽  
Vol 908 (1) ◽  
pp. 9
Author(s):  
Mukesh K. Vyas ◽  
Asaf Pe’er ◽  
David Eichler
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Emission Model ◽  
Prompt Emission

scholarly journals Systematic behaviours of different quantities related to sequential prompt emission in fission

2020 ◽  
Vol 239 ◽  
pp. 05016
Author(s):  
Anabella Tudora
Keyword(s):  
Emission Model ◽  
Los Alamos ◽  
Temperature Distributions ◽  
Residual Temperature ◽  
Deterministic Modelling ◽  
Recursive Equations ◽  
Prompt Emission ◽  
Residual Fragments

The deterministic modelling of sequential prompt emission in fission based on recursive equations of residual temperature was applied to numerous fission cases. This fact emphasized systematics and correlations between different quantities characterizing the residual fragments and the sequential emission. General forms of residual temperature distributions for each emission sequence are determined on the basis of these systematics, having as application the inclusion of sequential emission into the Los Alamos model. Also the systematics can serve to obtain indicative values of different average quantities in the absence of any prompt emission model.

Groundwater protection and diffuse nitrogen emissions to surface waters – which catchment areas have to be considered?

2007 ◽  
Vol 7 (3) ◽  
pp. 103-110
Author(s):  
C. Schilling ◽  
M. Zessner ◽  
A.P. Blaschke ◽  
D. Gutknecht ◽  
H. Kroiss
Keyword(s):  
Surface Water ◽  
Total Nitrogen ◽  
Surface Waters ◽  
Flow Path ◽  
Emission Model ◽  
Catchment Scale ◽  
Danube Basin ◽  
Nitrogen Emissions ◽  
Nitrogen Levels ◽  
Catchment Areas

Two Austrian case study regions within the Danube basin have been selected for detailed investigations of groundwater and surface water quality at the catchment scale. Water balance calculations have been performed using the conceptual continuous time SWAT 2000 model to characterise catchment hydrology and to identify individual runoff components contributing to river discharge. Nitrogen emission calculations have been performed using the empirical emission model MONERIS to relate individual runoff components to specific nitrogen emissions and for the quantification of total nitrogen emissions to surface waters. Calculated total nitrogen emissions to surface waters using the MONERIS model were significantly influenced by hydrological conditions. For both catchments the groundwater could be identified as major emission pathway of nitrogen emissions to the surface waters. Since most of the nitrogen is emitted by groundwater to the surface water, denitrification in groundwater is of considerable importance reducing nitrogen levels in groundwater along the flow path towards the surface water. An approach was adopted for the grid-oriented estimation of diffuse nitrogen emissions based on calculated groundwater residence time distributions. Denitrification in groundwater was considered using a half life time approach. It could be shown that more than 90% of the total diffuse nitrogen emissions were contributed by areas with low groundwater residence times and short distances to the surface water. Thus, managing diffuse nitrogen emissions the location of catchment areas has to be considered as well as hydrological and hydrogeological conditions, which significantly influence denitrification in the groundwater and reduce nitrogen levels in groundwater on the flow path towards the surface water.

scholarly journals Interpreting the X-ray afterglows of gamma-ray bursts with radiative losses and millisecond magnetars

2020 ◽  
Vol 499 (4) ◽  
pp. 5986-5992
Author(s):  
Nikhil Sarin ◽  
Paul D Lasky ◽  
Gregory Ashton
Keyword(s):  
Gravitational Wave ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Dipole Radiation ◽  
X Ray ◽  
Radiative Efficiency ◽  
Central Engine ◽  
Radiative Losses ◽  
Wave Emission ◽  
Prompt Emission

ABSTRACT The spin-down energy of millisecond magnetars has been invoked to explain X-ray afterglow observations of a significant fraction of short and long gamma-ray bursts. Here, we extend models previously introduced in the literature, incorporating radiative losses with the spin-down of a magnetar central engine through an arbitrary braking index. Combining this with a model for the tail of the prompt emission, we show that our model can better explain the data than millisecond-magnetar models without radiative losses or those that invoke spin-down solely through vacuum dipole radiation. We find that our model predicts a subset of X-ray flares seen in some gamma-ray bursts. We can further explain the diversity of X-ray plateaus by altering the radiative efficiency and measure the braking index of newly born millisecond magnetars. We measure the braking index of GRB061121 as $n=4.85^{+0.11}_{-0.15}$ suggesting the millisecond-magnetar born in this gamma-ray burst spins down predominantly through gravitational-wave emission.

Effect of Bottom Electrodes on Structural and Electrical Properties of Laser Ablated SrBi2Ta2O9 Thin Films

2001 ◽  
Vol 688 ◽  
Author(s):  
Rasmi R. Das ◽  
W. Pérez ◽  
P. Bhattacharya ◽  
Ram. S. Katiyar
Keyword(s):  
Thin Films ◽  
Barrier Height ◽  
Ferroelectric Properties ◽  
High Resistivity ◽  
Emission Model ◽  
X Ray Diffraction ◽  
Oxide Electrodes ◽  
Maximum Value ◽  
Structural And Electrical Properties ◽  
Raman Modes

AbstractWe have grown SrBi2Ta2O9 (SBT) thin films on various bottom electrodes such as Pt/TiO2/SiO2/Si (Pt) and LaNiO3/Pt/TiO2/SiO2/Si (LNO) substrates. The substrate temperature and oxygen pressure for the SBT film was maintained at 500 °C and 200 mTorr. As-grown films were post-annealed at a temperature of 800 °C. X-ray diffraction studies revealed that as-grown films were amorphous and crystallized to single phase after annealing. The difficulty of obtaining lowest Raman modes of SBT on platinized silicon substrate was overcome by using conducting oxide electrodes. Films grown on platinized silicon showed maximum value of remanent polarization (2Pr ∼ 21.5 μC/cm2) with coercive field (Ec) of ∼ 67 kV/cm. The degradation of ferroelectric properties of the films was observed with the introduction of 50 nm conducting LaNiO3 electrode at the interface of Pt and SBT film, which was attributed to high resistivity of the oxide electrode layers. Leakage current density was studied with the consideration of the Schottky emission model. The barrier height of the films grown on Pt and LNO were estimated to be 1.27 eV and 1.12 eV, respectively. The reduction of barrier height was attributed to the lower work function of the LNO electrode.

Application of a Phenomenological Model for the Engine-Out Emissions of Unburned Hydrocarbons in Driving Cycles

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Manuel Dorsch ◽  
Jens Neumann ◽  
Christian Hasse
Keyword(s):  
Phenomenological Model ◽  
Combustion Engine ◽  
Combustion Process ◽  
Formation Mechanisms ◽  
Emission Model ◽  
Engine Operation ◽  
Driving Cycles ◽  
Hc Emissions ◽  
Piston Crevice ◽  
Engine Map

In this work, the application of a phenomenological model to determine engine-out hydrocarbon (HC) emissions in driving cycles is presented. The calculation is coupled to a physical-based simulation environment consisting of interacting submodels of engine, vehicle, and engine control. As a novelty, this virtual calibration methodology can be applied to optimize the energy conversion inside a spark-ignited (SI) internal combustion engine at transient operation. Using detailed information about the combustion process, the main origins and formation mechanisms of unburned HCs like piston crevice, oil layer, and wall quenching are considered in the prediction, as well as the in-cylinder postoxidation. Several parameterization approaches, especially, of the oil layer mechanism are discussed. After calibrating the emission model to a steady-state engine map, the transient results are validated successfully against measurements of various driving cycles based on different calibration strategies of engine operation.

Sign in / Sign up

Export Citation Format

Share Document