Pulsar Wind Nebulae in Egret Error Boxes     

Mallory S. E. Roberts  Crystal L. Brogan  Bryan M. Gaensler  Jason W. T. Hessels  C.-Y. Ng  Roger W. Romani 《Astrophysics and Space Science》2005,297(1-4):93-100

A remarkable number of pulsar wind nebulae (PWN) are coincident with EGRET γ-ray sources. X-ray and radio imaging studies of unidentified EGRET sources have resulted in the discovery of at least six new pulsar wind nebulae (PWN). Stationary PWN (SPWN) appear to be associated with steady EGRET sources with hard spectra, typical for γ-ray pulsars. Their toroidal morphologies can help determine the geometry of the pulsar which is useful for constraining models of pulsed γ-ray emission. Rapidly moving PWN (RPWN) with more cometary morphologies seem to be associated with variable EGRET sources in regions where the ambient medium is dense compared to what is typical for the ISM.  相似文献   

The cosmic microwave background power spectrum out to ℓ= 1400 measured by the Very Small Array     

《Monthly notices of the Royal Astronomical Society》2003,341(4):L23-L28

  相似文献   

Relativist ic Corrections to the Thermal Sunyaev-Zel''''dovich Power Spectrum     

Hai-Ning LiNational Astronomical Observatories  Chinese Academy of Sciences  Beijing  lhnDepartment of Astronomy  Beijing Normal University  Beijing 《中国天文和天体物理学报》2003,3(5)

We present a quantitative estimate of the relativistic corrections to the thermal SZ power spectrum produced by the energetic electrons in massive clusters. The corrections are well within 10% for current experiments with working frequencies below v < 100 GHz, but become non-negligible at high frequencies v > 350 GHz. Moreover, the corrections appear to be slightly smaller at higher l or smaller angular scales. We conclude that there is no need to include the relativistic corrections in the theoretical study of the SZ power spectrum especially at low frequencies unless the SZ power spectrum is used for precision cosmology.  相似文献   

Towards a free–free template for CMB foregrounds     

C. Dickinson  R. D. Davies  R. J. Davis 《Monthly notices of the Royal Astronomical Society》2003,341(2):369-384

A full-sky template map of the Galactic free–free foreground emission component is increasingly important for high-sensitivity cosmic microwave background (CMB) experiments. We use the recently published Hα data of both the northern and southern skies as the basis for such a template.
The first step is to correct the Hα maps for dust absorption using the 100-μm dust maps of Schlegel, Finkbeiner & Davis. We show that for a range of longitudes, the Galactic latitude distribution of absorption suggests that it is 33 per cent of the full extragalactic absorption. A reliable absorption-corrected Hα map can be produced for ∼95 per cent of the sky; the area for which a template cannot be recovered is the Galactic plane area  | b | < 5°, l = 260°–0°–160°  and some isolated dense dust clouds at intermediate latitudes.
The second step is to convert the dust-corrected Hα data into a predicted radio surface brightness. The free–free emission formula is revised to give an accurate expression (1 per cent) for the radio emission covering the frequency range 100 MHz–100 GHz and the electron temperature range 3000–20 000 K. The main uncertainty when applying this expression is the variation of electron temperature across the sky. The emission formula is verified in several extended H  ii regions using data in the range 408–2326 MHz.
A full-sky free–free template map is presented at 30 GHz; the scaling to other frequencies is given. The Haslam et al. all-sky 408-MHz map of the sky can be corrected for this free–free component, which amounts to a  ≈6  per cent correction at intermediate and high latitudes, to provide a pure synchrotron all-sky template. The implications for CMB experiments are discussed.  相似文献   

Parameters of the intense X-ray and gamma-ray radiation from the solar flare of May 20, 2002, as observed from the Coronas-F spacecraft     

A. V. Bogomolov  A. P. Ignat’ev  K. Kudela  S. N. Kuznetsov  Yu. I. Logachev  O. V. Morozov  I. N. Myagkova  S. N. Oparin  A. A. Pertsov  S. I. Svertilov  B. Yu. Yushkov 《Astronomy Letters》2003,29(3):199-204

We consider temporal, spectral, and polarization parameters of the hard X-ray and gamma-ray radiation observed during the solar flare of May 20, 2002, in the course of experiments with the SONG and SPR-N instruments onboard the Coronas-F spacecraft. This flare is one of the most intense gamma-ray events among all of the bursts of solar hard electromagnetic radiation detected since the beginning of the Coronas-F operation (since July 31, 2001) and one of the few gamma-ray events observed during solar cycle 23. A simultaneous analysis of the Coronas-F and GOES data on solar thermal X-ray radiation suggests that, apart from heating due to currents of matter in the the flare region, impulsive heating due to the injection of energetic electrons took place during the near-limb flare S21E65 of May 20, 2002. These electrons produced intense hard X-ray and gamma-ray radiation. The spectrum of this radiation extends up to energies ≥7 MeV. Intense gamma-ray lines are virtually unobservable against the background of the nonthermal continuum. The polarization of the hard X-ray (20–100 keV) radiation was estimated to be ≤15–20%. No significant increase in the flux of energetic protons from the flare under consideration was found. At the same time, according to ACE data, the fluxes of energetic electrons in interplanetary space increased shortly (～25 min) after the flare.  相似文献   

Search For Correlations Between Batse Gamma-Ray Bursts and Supernovae     

JiřÍ Polcar  Martin Topinka  Graziella Pizzichini  Eliana Palazzi  Nicola Masetti  RenÉ Hudec  Věra HudcovÁ 《Astrophysics and Space Science》2005,296(1-4):485-488

We report on our statistical research of space–time correlated supernovae and CGRO-BATSE gamma-ray bursts (GRBs). There exists a significantly higher abundance of core-collapse supernovae among the correlated supernovae, but the subset of all correlated objects does not seem to be physically different from the whole set.  相似文献   

Acceleration of anomalous cosmic rays at the heliospheric termination shock     

Berezhko  E. G.  Ksenofontov  L. T. 《Astronomy Letters》2005,31(12):836-843

Astronomy Letters - The acceleration of anomalous cosmic rays (ACRs) at the heliospheric termination shock and their influence on the shock structure and location are analyzed in terms of a...  相似文献   

Radio interferometers with wide bandwidths     

Ravi Subrahmanyan 《Monthly notices of the Royal Astronomical Society》2004,348(4):1208-1214

  相似文献   

A 59-second period in the very high energy gamma-ray emission from the Geminga pulsar     

Yu. I. Neshpor  A. A. Stepanyan 《Astronomy Letters》2001,27(12):794-798

An analysis of our observations of the Geminga object with the GT-48 ground-based gamma-ray telescope has shown that its very-high-energy gamma-ray flux is modulated with a 59-s period. The 59-s period and its time derivative previously inferred from satellite data have been confirmed. According to our data, the period was 61.94 s in 1997 at MSD=50573. The statistical significance of this result is (1?4.5)×10^?4.  相似文献   

Observational constraint on the fourth derivative of the inflaton potential     

Chiara Caprini  Steen H. Hansen  Martin Kunz 《Monthly notices of the Royal Astronomical Society》2003,339(1):212-214

  相似文献