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Colloquium by Bozena Czerny (Nicolaus Copernicus Astronomical Center)

Quasars as dark energy probes


Why quasars are important in cosmology? They are essential ingredients of the Universe, affecting its evolution but they can serve at the same time as tools for studying the Universe structure. I will concentrate on the second aspect. The dark energy, responsible for the accelerated expansion of the Universe is the largest puzzle of the present day cosmology, and quasars can be used as tracers of the expansion rate. Quasars are bright, and easily observed up to large distances, so they can be used as cosmological probes in a similar way as Supernovae Ia. Their advantage is that quasars are numerous, they are persistent sources, and they do not seem to show significant evolution with redshift. The disadvantage is that they are not simple standard candles. I will discuss the proposed methods to go around the last problem, including the project being now done by our group. I will conclude showing the expected progress due to on-going or planned sky surveys.

Time: Oct. 21,  2015, 2:30 pm

Venue: A601, NAOC