搜索结果: 151-165 共查到“理学 X-ray”相关记录739条 . 查询时间(0.093 秒)
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
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...
A Model for the Origin of High Density in Loop-top X-ray Sources
Model Origin Density Loop-top X-ray Sources
2011/10/8
Super-hot looptop sources, detected in some large solar flares, are compact sources of HXR emission with spectra matching thermal electron populations exceeding 30 megakelvins. High observed emission ...
Short Gamma-ray Bursts: the mass of the accretion disk and the initial radius of the outflow
Short Gamma-ray Bursts:accretion disk initial radius outflow
2011/10/9
In this work we estimate the accretion-disk mass in the specific scenario of binary-neutron-star-merger with current observational data. Assuming that the outflows of short Gamma-ray Bursts (GRBs) are...
The effects of X-ray absorption variability in NGC 4395
galaxies: active – galaxies: individual: NGC 4395 – X-rays: galaxies
2011/10/8
We present a new X-ray analysis of the dwarf Seyfert galaxy NGC 4395, based on two archival XMM-Newton and Suzaku observations. This source is well known for a series of remarkable properties: one of ...
Search for Nuclei Sources in the Ultra-High Energy Cosmic Ray Data
Ultra-High Energy Cosmic Rays Galactic Magnetic Field
2011/10/8
We present a new method to search for heavy nuclei sources, on top of background, in the Ultra-High Energy Cosmic Ray data. We apply it to the 69 events with energies E>55 EeV published by the Pierre ...
Search for Individual Ultrahigh Energy Cosmic Ray Sources in the Future Data
ultra-high energy cosmic rays magnetic fi elds Galaxy
2011/10/8
We propose a new way to detect individual bright Ultra-High Energy Cosmic Ray (UHECR) sources above background if the Galactic Magnetic Field (GMF) gives the main contribution to UHECR deflections. Th...
Discovery and identification of infrared counterpart candidates of four Galactic centre low mass X-ray binaries
X-rays: binaries – infrared: stars – X-rays: individuals: XTE J1637− 498, IGRJ17379− 3747, IGR J17585− 3057, GX9+1
2011/9/30
The near infrared (nIR)/optical counterparts of low mass X-ray binaries (LMXBs) are often observationally dim and reside in high source density fields which make their identification problematic; howe...
AGN Unification at z ~ 1: u - R Colors and Gradients in X-ray AGN Hosts
Unification Colors Gradients Hosts
2011/10/8
We present uncontaminated rest-frame u - R colors of 78 X-ray-selected AGN hosts at 0.5 < z < 1.5 in the Chandra Deep Fields measured with HST/ACS/NICMOS and VLT/ISAAC imaging. We also present spatial...
The Evolution of Radio Galaxies and X-ray Point Sources in Coma Cluster Progenitors Since z~1.2
Evolution Radio Galaxies Point Sources Cluster Progenitors Since
2011/9/30
Using Chandra imaging spectroscopy and Very Large Array (VLA) L-band radio maps, we have identified radio sources at P_{1.4GHz} >=5x10^{23} W Hz^{-1} and X-ray point sources (XPSs) at L_{0.3-8keV}>=5x...
IceCube as a three-dimensional air-shower array covers an energy range of the cosmic-ray spectrum from below 1 PeV to approximately 1 EeV. This talk is a brief review of the function and goals of IceT...
Gamma-Ray Constraints on Maximum Cosmogenic Neutrino Fluxes and UHECR Source Evolution Models
Gamma-Ray Constraints Cosmogenic Neutrino Fluxes Source Evolution Models
2011/9/29
The dip model assumes that the ultra-high energy cosmic rays (UHECRs) above 10$^{18}$ eV consist exclusively of protons and is consistent with the spectrum and composition measure by HiRes. Here we pr...
Gamma Ray Burst origin and their afterglow: story of a discovery and more
Burst origin afterglow: story discovery more
2011/9/29
In this paper we review the story of the BeppoSAX discovery of the Gamma Ray Burst afterglow and their cosmological distance, starting from their first detection with Vela satellites and from the effo...
Highly absorbed X-ray binaries in the Small Magellanic Cloud
galaxies: Small Magellanic Cloud – stars: emission–line, Be – X-rays: binaries
2011/9/29
Many of the high mass X-ray binaries (HMXRBs) discovered in recent years in our Galaxy are characterized by a high absorption, most likely intrinsic to the system, which hampers their detection at the...
X-ray flare candidates in short gamma-ray bursts
gamma-ray: bursts – radiation mechanism: non-thermal –X-rays
2011/9/30
We present the first systematic study of X-ray flare candidates in short gamma-ray bursts (SGRBs) exploiting the large 6-year Swift database with the aim to constrain the physical nature of such fluct...
Fermi Large Area Telescope Observations of the Active Galaxy 4C +55.17: Steady, Hard Gamma-Ray Emission and its Implications
Steady Hard Gamma-Ray Emission Implications
2011/9/29
We report Fermi/LAT observations and broad-band spectral modeling of the radio-loud active galaxy 4C +55.17 (z=0.896), formally classified as a flat-spectrum radio quasar. Using 19 months of all-sky s...