搜索结果: 1-15 共查到“天文学 Background”相关记录26条 . 查询时间(0.105 秒)
Hydrodynamic simulation of the cosmological X-ray background
observations large scale structure of Universe
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2014/12/26
We use a hydrodynamic simulation of an inflationary cold dark matter model with a cosmological constant to predict properties of the extragalactic X-ray background (XRB). We focus on emission from the...
The AGN fraction of submm-selected galaxies and contributions to the submm/mm-wave extragalactic background light
galaxies contributions
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2014/12/22
We present a comparison of the SCUBA half degree extragalactic survey (SHADES) at 450 μm, 850 μm and 1100 μm with deep guaranteed time 15 μm AKARI FU-HYU survey data and Spitzer guaranteed time data a...
The contribution from blazar cascade emission to the extragalactic gamma-ray background: What a role does the extragalactic magnetic field play?
diffuse radiation galaxies active gamma rays general
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2012/2/21
We estimate the contribution to the extragalactic gamma-ray background (EGRB) from both intrinsic and cascade emissions produced by blazars using a simple semi- analysis method for two models of the b...
Compensated Isocurvature Perturbations and the Cosmic Microwave Background
Compensated Isocurvature Perturbations Microwave Background
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2011/10/19
Measurements of cosmic microwave background (CMB) anisotropies constrain isocurvature fluctuations between photons and non-relativistic particles to be sub-dominant to adiabatic fluctuations. Perturba...
Ultra High Energy Comic Rays in the Cosmic Microwave Background
Ultra High Energy Comic Rays Cosmic Microwave Background
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2011/10/13
We consider the propagation of ultra high energy cosmic rays (UHECR), for energies greater than E > 10^{14} eV but less than E < 10^{26} eV, in the cosmic medium of the Cosmic Microwave Background (CM...
The impact of a stochastic gravitational-wave background on pulsar timing parameters
impact stochastic gravitational-wave background timing parameters
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2011/10/12
Gravitational waves are predicted by Einstein's theory of general relativity as well as other theories of gravity. The rotational stability of the fastest pulsars means that timing of an array of thes...
Random matrix approach in search for weak signals immersed in background noise
Random matrix approach search signals immersed background noise
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2011/10/17
We present new, original and alternative method for searching signals coded in noisy data. The method is based on the properties of random matrix eigenvalue spectra. First, we describe general ideas a...
Extragalactic Background Light and Gamma-Ray Attenuation
Luminosity density, galaxy spectral energy evolution, extragalactic background light, semi-analytic models of the evolving galaxy population, gamma ray attenuation
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2011/10/8
Data from (non-) attenuation of gamma rays from active galactic nuclei (AGN) and gamma ray bursts (GRBs) give upper limits on the extragalactic background light (EBL) from the UV to the mid-IR that ar...
Impacts of Dark Stars on Reionization and Signatures in the Cosmic Microwave Background
Impacts Dark Stars Reionization Signatures Cosmic
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2011/9/30
We perform a detailed and systematic investigation of the possible impacts of dark stars upon the reionization history of the Universe, and its signatures in the cosmic microwave background (CMB). We ...
M-band Imaging of the HR 8799 Planetary System Using an Innovative LOCI-based Background Subtraction Technique
Planetary Using Innovative Background Subtraction Technique
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2011/9/28
Multi-wavelength observations/spectroscopy of exoplanetary atmospheres are the basis of the emerging exciting field of comparative exoplanetology. The HR 8799 planetary system is an ideal laboratory t...
Cosmological Perturbation Theory With Background Anisotropic Curvature
Cosmological Perturbation Theory Background Anisotropic Curvature
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2011/10/18
The theory of cosmological perturbations is extended to spacetimes displaying isotropic expansion but anisotropic curvature. The perturbed Einstein equation and Boltzmann equations for massless and ma...
Observing the Big Bounce with Tensor Modes in the Cosmic Microwave Background: Phenomenology and Fundamental LQC Parameters
Quantum gravity quantum cosmology
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2010/11/12
Cosmological models where the standard Big Bang is replaced by a bounce have been studied for
decades. The situation has however dramatically changed in the last years for two reasons. First,because ...
The Gamma-Ray Background Constrains the Origins of the Radio and X-Ray Backgrounds
cosmic rays gamma rays diffuse background radio continuum galaxies X-rays
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2010/11/9
Cosmic ray protons generate γ-rays, neutrinos, and secondary electrons and positrons (e±) through pionproducing collisions with gas atoms. Any synchrotron or Inverse Compton (IC) radiation from second...
Instruments of RT-2 Experiment onboard CORONASPHOTON and their test and evaluation IV: Background Simulations using GEANT-4 Toolkit
Radiation detectors X- and gamma-ray telescopes and instrumentation
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2010/11/16
Hard X-ray detectors in space are prone to background signals due to the ubiquitous cosmic rays and cosmic diffuse background radiation that continuously bom-bards the satellites which carry the detec...
The impact of spatial fluctuations in the ultra-violet background on intergalactic carbon and silicon
methods: numerical intergalactic medium quasars absorption lines
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2010/11/12
Spatial inhomogeneities in the spectral shape of the ultra-violet background (UVB) at the tail-end of He II reionisation are thought to be the primary cause of the large fluctuations observed in the H...