6 research outputs found

    The Race Between Stars and Quasars in Reionizing Cosmic Hydrogen

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    The cosmological background of ionizing radiation has been dominated by quasars once the Universe aged by ~2 billion years. At earlier times (redshifts z>3), the observed abundance of bright quasars declined sharply, implying that cosmic hydrogen was reionized by stars instead. Here, we explain the physical origin of the transition between the dominance of stars and quasars as a generic feature of structure formation in the concordance LCDM cosmology. At early times, the fraction of baryons in galaxies grows faster than the maximum (Eddington-limited) growth rate possible for quasars. As a result, quasars were not able to catch up with the rapid early growth of stellar mass in their host galaxies.Comment: 5 pages, 1 figure, Accepted for publication in JCA

    Molecular Targets, Anti-cancer Properties and Potency of Synthetic Indole-3-carbinol Derivatives

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    Recent Investigations on Rheumatism and Arthritis in the United States

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    Neurochemistry of Drug Abuse

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