ELECTROMAGNETIC CASCADES IN MAGNETIZED MEDIA

2010 ◽  
Vol 19 (06) ◽  
pp. 671-676 ◽  
Author(s):  
LEONARDO J. PELLIZZA ◽  
MARIANA ORELLANA ◽  
GUSTAVO E. ROMERO
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Weak Magnetic Field ◽  
Numerical Scheme ◽  
Gamma Ray ◽  
Broad Band ◽  
Broad Band Emission ◽  
Band Emission ◽  
Self Consistent ◽  
Open Issue

The investigation of the astrophysical nature of gamma-ray sources and the processes responsible for their broad-band emission requires a detailed modeling of their observable spectrum, in which electromagnetic cascades can play an important role. An open issue in this modeling is the effect of magnetic fields in the development of cascades. In this paper we present a novel numerical scheme to compute this effect in a self-consistent way. Applied to a toy model, our scheme reproduces the features expected for cascades in the strong and weak magnetic field regimes.

scholarly journals Multiwavelength observations of PSR J2032+4127 during the 2017 periastron passage

2020 ◽  
Vol 495 (1) ◽  
pp. 365-374 ◽  
Author(s):  
M Chernyakova ◽  
D Malyshev ◽  
P Blay ◽  
B van Soelen ◽  
S Tsygankov
Keyword(s):  
Gamma Ray ◽  
Broad Band ◽  
Joint Analysis ◽  
Spectral Evolution ◽  
Optical Telescope ◽  
X Ray ◽  
Broad Band Emission ◽  
Band Emission ◽  
Mass Outflow ◽  
Be Star

ABSTRACT PSR J2032+4127 is only the second known gamma-ray binary where it is confirmed that a young radio pulsar is in orbit around a Be-star. The interaction of the pulsar wind with the mass outflow from the companion leads to broad-band emission from radio up to TeV energies. In this paper we present results of optical monitoring of the 2017 periastron passage with the Nordic Optical Telescope. These observations are complemented by X-ray (Swift/XRT, NuSTAR) and GeV (Fermi/LAT) monitoring. Joint analysis of the evolution of the parameters of the H α line and the broad-band (X-ray to TeV) spectral shape allows us to propose a model linking the observed emission to the interaction of the pulsar and Be-star winds under the assumption of the inclined disc geometry. Our model allows the observed flux and spectral evolution of the system to be explained in a self-consistent way.

scholarly journals Late X-ray flares from the interaction of a reverse shock with a stratified ejecta in GRB afterglows: simulations on a moving mesh

2020 ◽  
Vol 495 (3) ◽  
pp. 2979-2993 ◽  
Author(s):  
Eliot H Ayache ◽  
Hendrik J van Eerten ◽  
Frédéric Daigne
Keyword(s):  
Gamma Ray ◽  
Mass Density ◽  
Broad Band ◽  
Moving Mesh ◽  
Late Time ◽  
Causal Connection ◽  
Reverse Shock ◽  
X Ray ◽  
Broad Band Emission ◽  
Band Emission

ABSTRACT Late activity of the central engine is often invoked in order to explain the flares observed in the early X-ray afterglow of gamma-ray bursts, either in the form of an active neutron star remnant or (fall-back) accretion on to a black hole. However, these scenarios are not always plausible, in particular when flares are delayed to very late times after the burst. Recently, a new scenario was proposed that suggests X-ray flares can be the result of the passing of a long-lived reverse shock through a stratified ejecta, with the advantage that it does not require late-time engine activity. In this work, we numerically demonstrate this scenario to be physically plausible, by performing one-dimensional simulations of ejecta dynamics and emission using our novel moving-mesh relativistic hydrodynamics code. Improved efficiency and precision over previous work enables the exploration of a broader range of set-ups. We can introduce a more physically realistic description of the circumburst medium mass density. We can also locally trace the cooling of electrons when computing the broad-band emission from these set-ups. We show that the synchrotron cooling time-scale can dominate the flare decay time if the stratification in the ejecta is constrained to a localized angular region inside the jet, with size corresponding to the relativistic causal connection angle, and that it corresponds to values reported in observations. We demonstrate that this scenario can produce a large range of observed flare times, suggesting a connection between flares and initial ejection dynamics rather than with late-time remnant activity.

scholarly journals Broad-band Emission from Gamma-ray Binaries

2018 ◽  
Author(s):  
Josep M Paredes ◽  
Pol Bordas
Keyword(s):  
Gamma Ray ◽  
Broad Band ◽  
Broad Band Emission ◽  
Band Emission

scholarly journals The challenging SED of AP Librae

2011 ◽  
Vol 7 (S284) ◽  
pp. 411-413 ◽  
Author(s):  
David Sanchez ◽  
Berrie Giebels ◽  
Pascal Fortin ◽  
Keyword(s):  
Spectral Energy Distribution ◽  
Broad Band ◽  
Low Frequency ◽  
Theoretical Models ◽  
Intermediate Frequency ◽  
High Energy ◽  
Spectral Energy ◽  
Broad Band Emission ◽  
Band Emission ◽  
Bl Lac

AbstractMatching the broad-band emission of active galaxies with the predictions of theoretical models can be used to derive constraints on the properties of the emitting region and to probe the physical processes involved. AP Librae is the third low frequency peaked BL Lac (LBL) detected at very high energy (VHE, E>100GeV) by an Atmospheric Cherenkov Telescope; most VHE BL Lacs (34 out of 39) belong to the high-frequency and intermediate-frequency BL Lac classes (HBL and IBL). LBL objects tend to have a higher luminosity with lower peak frequencies than HBLs or IBLs. The characterization of their time-averaged spectral energy distribution is challenging for emission models such as synchrotron self-Compton (SSC) models.

Microscintillator of Ce Doped β-NaLuF4 in Uniform Hexagonal Prism Morphology by a Facile Hydrothermal Method

2014 ◽  
Vol 541-542 ◽  
pp. 220-224
Author(s):  
Li Sha Liu ◽  
Hao Hong Chen ◽  
Bi Qiu Liu ◽  
Bin Tang ◽  
Zhi Jia Sun ◽  
...  
Keyword(s):  
Hydrothermal Method ◽  
Hexagonal Phase ◽  
Broad Band ◽  
High Energy ◽  
Hexagonal Prism ◽  
Facile Hydrothermal Method ◽  
X Ray ◽  
Strong Broad Band ◽  
Broad Band Emission ◽  
Band Emission

To explore micro-or nanoscintillator with a controllable architecture, a novel facile hydrothermal method easy for commercial run was used to synthesize pure and Ce doped β-NaLuF4 microcrystals at 453K. The morphology of uniform hexagonal prism with 3.3μm in diameter and 1.4 μm in thickness, respectively, is presented by the results of scanning electron microscopy (SEM). Powder X-ray diffraction (PXRD) patterns show the products are both pure hexagonal phase. Different from the undoped product without any irradiation, the Ce doped product has given strong broad band emission attributed to 5d4f transition of Ce3+, which can be potentially used as scintillator for biomedical imaging and detectors for high energy such as X-ray and γray. This synthetical strategy extends the understanding about nanomaterial chemistry and can be also useful for other systems such as fluorides, oxides and sulfides.

Preparation and Luminescence Property of LaMgAl11O19

2012 ◽  
Vol 519 ◽  
pp. 224-227 ◽  
Author(s):  
Xin Min ◽  
Ming Hao Fang ◽  
Yan Gai Liu ◽  
Zhao Hui Huang
Keyword(s):  
Solid State ◽  
Luminescence Property ◽  
Broad Band ◽  
Emission Spectra ◽  
Synthesis Temperature ◽  
Solid State Lasers ◽  
Broad Band Emission ◽  
Band Emission ◽  
Air Atmosphere ◽  
Fluorescent Lamps

Lanthanum magnesium hexaaluminate (LaMgAl11O19, LMA) has attracted much interest as its widely used in solid state lasers, TV phosphors and fluorescent lamps. In this paper, LaMgAl11O19 ceramic was pressureless sintered at 1650 °C for 10 h in air atmosphere using LaMgAl11O19 powders prepared by solid-state reaction at 1500 °C for 4 h. The result indicated that the synthesis temperature of LaMgAl11O19 powders was about 1500 °C. The LMA ceramic sample was dense and had a microstructure of platelet-like gains. The excitation spectrum shows two wide bands with the peaks at about 254 nm and 265 nm by monitoring the strongest 362 nm emission, and the emission spectra is consisted of a broad band emission with their peaks near 362 nm with a half-width about 5 nm exciting with 265 nm wavelength.

Synthesis, Characterization and Photophysical Properties of Rhenium(I) Complexe with 2-(naphthalen-2-yl)-1-phenyl-1H-imidazo[4,5-f][1,10]phenanthroline

2014 ◽  
Vol 988 ◽  
pp. 66-69
Author(s):  
Qiang Li ◽  
Le Li ◽  
Rong Feng Zhong ◽  
Hai Di Cai ◽  
Feng Zhao
Keyword(s):  
Experimental Data ◽  
Solid State ◽  
Photophysical Properties ◽  
Broad Band ◽  
High Energy ◽  
H Nmr ◽  
Emission Maximum ◽  
Broad Band Emission ◽  
Band Emission

In this paper, a Re(I) complex [Re(CO)3(E2)Cl], where E2 = 2-(naphthalen-2-yl)-1-phenyl-1H-imidazo[4,5-f][1,10]phenanthroline(E2), was synthesized and characterized by 1H NMR successfully. Experimental data confirm that Re(I) complex [Re(CO)3(E2)Cl] is high-energy-emitting one. The broad band emission upon excitation at λ = 400 nm with the emission maximum locates at λ = 581 nm in solid state and 614nm in CH2Cl2 solution were observed.

scholarly journals Orientation effects on the near-infrared broad-band emission of quasars

2019 ◽  
Vol 485 (1) ◽  
pp. 1405-1411 ◽  
Author(s):  
Susanna Bisogni ◽  
Elisabeta Lusso ◽  
Alessandro Marconi ◽  
Guido Risaliti
Keyword(s):  
Near Infrared ◽  
Broad Band ◽  
Broad Band Emission ◽  
Band Emission ◽  
Orientation Effects
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