Search results for "Radiative efficiency"

showing 3 items of 3 documents

Optical properties and microstructure of 2.02-3.30 eV ZnCdO nanowires: effect of thermal annealing

2013

International audience; ZnCdO nanowires with up to 45% Cd are demonstrated showing room temperature photoluminescence (PL) down to 2.02 eV and a radiative efficiency similar to that of ZnO nanowires. Analysis of the microstructure in individual nanowires confirms the presence of a single wurtzite phase even at the highest Cd contents, with a homogeneous distribution of Cd both in the longitudinal and transverse directions. Thermal annealing at 550 C yields an overall improvement of the PL, which is blue-shifted as a result of the homogeneous decrease of Cd throughout the nanowire, but the single wurtzite structure is fully maintained.

010302 applied physicsTelecomunicacionesPhotoluminescenceMaterials sciencePhysics and Astronomy (miscellaneous)Annealing (metallurgy)business.industryWide-bandgap semiconductorNanowire02 engineering and technology021001 nanoscience & nanotechnologyMicrostructure01 natural sciencesHomogeneous distributionRadiative efficiency0103 physical sciences[PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci]Optoelectronics0210 nano-technologybusinessWurtzite crystal structure
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A model of M87 nuclear emission without ADAF

2007

We present a simple physical model of the central source emission in the M87 galaxy. It is well known that the observed X‐ray luminosity from this galactic nucleus is much lower than the predicted one, if a standard radiative efficiency is assumed. Up to now the main model invoked to explain such a luminosity is the ADAF (Advection‐Dominated‐Accretion‐Flow) model. Our approach supposes only a simple axis‐symmetric adiabatic accretion with a low angular momentum together with the bremsstrahlung emission process in the accreting gas. With no other special hypothesis on the dynamics of the system, this model agrees well enough with the luminosity value measured by Chandra.

PhysicsAngular momentumActive galactic nucleusAstrophysics::High Energy Astrophysical PhenomenaBremsstrahlungAstrophysics::Cosmology and Extragalactic AstrophysicsAstrophysicsGalactic nucleiGalaxyAccretion (astrophysics)Radiative efficiencyAstrophysics::Solar and Stellar AstrophysicsAdiabatic processAstrophysics::Galaxy Astrophysics
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A Simple Model of Radiative Emission in M87

2005

We present a simple physical model of the central source emission in the M87 galaxy. It is well known that the observed X-ray luminosity from this galactic nucleus is much lower than the predicted one, if a standard radiative efficiency is assumed. Up to now the main model invoked to explain such a luminosity is the ADAF (Advection-Dominated-Accretion-Flow) model. Our approach supposes only a simple axis-symmetric adiabatic accretion with a low angular momentum together with the bremsstrahlung emission process in the accreting gas. With no other special hypothesis on the dynamics of the system, this model agrees well enough with the luminosity value measured by Chandra.

PhysicsAngular momentumAstrophysics::High Energy Astrophysical PhenomenaAstrophysics (astro-ph)BremsstrahlungFOS: Physical sciencesAstronomy and AstrophysicsAstrophysics::Cosmology and Extragalactic AstrophysicsAstrophysicsAstrophysicsaccretion accretion disks black hole physics hydrodynamicsGalaxyAccretion (astrophysics)Space and Planetary ScienceRadiative efficiencyRadiative transferAstrophysics::Solar and Stellar AstrophysicsAdiabatic processAstrophysics::Galaxy AstrophysicsThe Astrophysical Journal
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