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Supernovae seen through gravitational telescopes

Supernovae seen through gravitational telescopes

Tanja Petrushevska

Department of Physics, Faculty of Science, Stockholm
The Oskar Klein Centre for Cosmo Particle Physics, Sweden

v sredo, 26. aprila 2017, ob 12. uri v predavalnici F4 (Jadranska 19, Ljubljana)

Galaxies, and clusters of galaxies, can act as gravitational lenses and magnify the light of objects behind them. The effect enables observations of very distant supernovae, that otherwise would be too faint to be detected by existing telescopes, and allows studies of the frequency and properties of these rare phenomena when the universe was young. Under the right circumstances, multiple images of the lensed supernovae can be observed, and due to the variable nature of the objects, the difference between the arrival times of the images can be measured. Since the images have taken different paths through space before reaching us, the time-differences are sensitive to the expansion rate of the universe. One class of supernovae, Type Ia, are of particular interest to detect. Their well known brightness can be used to determine the magnification, which can be used to understand the lensing systems. I will also report our discovery of the first resolved multiply-imaged gravitationally lensed supernova Type Ia.

Na zgornji sliki je shema učinka, ki ga ima gravitacijsko lečenje zaradi bližnje galaksije na svetlobo, ki prihaja iz oddaljene galaksije. Bližnja galaksija deluje kot leča, ki popači sliko oddaljenih objektov ter jih naredi svetlejše, v primeru na sliki je prisoten prstan svetlobe, ki mu pravimo Einsteinov prstan. Analiza popačitve je pokazala, da nekatere izmed oddaljenih galaksij, v katerih nastajajo nove zvezde, svetijo kot 40 tisoč milijard Sonc ter da je povečava zaradi lečenja kar 22-kratna.

 

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