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121.
The discovery of the microlensing effect has found out the new population — dark bodies having mass of the order of 0.1M
which form the halo of our Galaxy. There are two main criteria which identify a light curve as the reveal of the microlensing effect. They are symmetry of the light curve and equal amplification in different colors. We consider polarization of the light beam arising in microlensing effect and find that additional test is possible — polarization of light in the case of a finite star disk. Consequences of polarization are also considered. 相似文献
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Matthias Beilicke 《Astrophysics and Space Science》2007,309(1-4):139-145
The HESS experiment (High Energy Stereoscopic System), consisting of four imaging atmospheric Cherenkov telescopes (IACTs)
in Namibia, has observed many extragalactic objects in the search for very high energy (VHE) γ-ray emission. These objects include active galactic nuclei (AGN), notably Blazars, Seyferts, radio galaxies, starburst galaxies
and others. Beyond the established sources, γ-ray emission has been detected for the first time from several of these objects by HESS, and their energy spectra and variability
characteristics have been measured. Multi-wavelength campaigns, including X-ray satellites, radio telescopes, and optical
observations, have been carried out for AGNs, in particular for PKS 2155-304, H 2356-309 and 1ES 1101-232, for which the implications
concerning emission models are presented. Also results from the investigations of VHE flux variability from the giant radio
galaxy M 87 are shown.
For the HESS Collaboration. 相似文献
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Huib Jan Van Langevelde Ylva PihlstrÖm Anthony Beasley 《Astrophysics and Space Science》2005,295(1-2):249-255
Centaurus A, the nearest AGN shows molecular absorption in the millimeter and radio regime. By observing the absorption with VLBI, we try to constrain the distribution of the gas, in particular whether it resides in the circumnuclear region. Analysis of VLBA observations in four OH and two H2CO transitions is presented here, as well as molecular excitation models parameterized with distance from the AGN. We conclude that the gas is most likely associated with the tilted molecular ring structure observed before in molecular emission and IR continuum. The formaldehyde absorption shows small-scale absorption which requires a different distribution than the hydroxyl. 相似文献
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The relations between star formation rates along the spiral arms and the velocities of gas inflow into the arms in the grand‐design galaxy NGC 628 were studied. We found that the radial distribution of the average star formation rate in individual star formation regions in regular spiral arms correlates with the velocity of gas inflow into the spiral arms. Both distributions have maxima at a galactocentric distance of 4.5–5 kpc. There are no correlations between the radial distributions of the average star formation rate in star formation regions in spiral arms and outside spiral arms in the main disc. We also did not find a correlation between the radial distribution of the average star formation rate in star formation regions in spiral arms and the H I column density. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献