Dark energy is responsible for the accelerated expansion of the Universe
but its nature is unknown. The precise mesurements will allow observational determination of the possible evolution with time which can open ways to interprete this phenomenon. The use of several independent astronomical probes is needed to get accurate and reliable results since every probe has its particular systematic problems/biases. Quasars do not seem to be obvious standard candles but they are numerous, cover a very broad range of distances from nearby active galaxies to distant high redshift quasars. There are several methods to use quasars. One of the
method is based on time delay of the line emission with respect to the continuum. We developed a theory which explains the measured delay-luminosity relation known for nearby sources and allows to extrapolate this type of relation towards higher black hole mass sources. Preliminary studies are being done using our data from the dedicated campaign with the 11-m SALT telescope. Later the method will be applied to expected spectroscopic surveys and photmetric surveys like LSST. The advantage of using quasars lies in their weak evolution of properties with redshift.
Prof. Bozena Czerny (波兰理论物理中心)
Prof.Bozena Czerny, works in Center for Theoretical Physics, Warsaw, Poland.In 1984,she got his Ph.D.in astrophysics, N. Copernicus Astronomical Center, Polish Academy of Sciences,Warsaw. In 1996, she was awarded the title of full professor by the President of Poland. Her main research interests focuses on observational aspects of disk accretion onto supermassive black holes, and currently concentrating on cosmological applications of quasars. She is the Scientific Editor of the Astrophysical Journal (since 2012), the Secretary of the Commission 19 “Astrophysics” of the International Union of Pure and Applied Physics (IUPAP) (till 2011), and the member of the Council of National Science Center (NCN: the financing agency for basic research in Poland). She was the President of the Polish Astronomical Society.