Caught in the Act?

نویسنده

  • Zoltán Haiman
چکیده

Galaxies are thought to be surrounded by massive halos of dark matter, each outweighing its galaxy by a factor of about eight. The visible part of a galaxy, occupying the inner 10% of the halo, consists of a mixture of stars and gas. Galaxies harbour a giant black hole at their centres, which in some cases is actively fuelled as it sucks in surrounding gas. In especially active galaxies, called quasars, the fuelling rate is so high that the radiation generated close to the black hole outshines the cumulative star–light from the entire galaxy. The sequence of cosmic events that leads to this configuration is still largely mysterious. How does gas condense into the central regions of the dark–matter halo? At what stage of the gas condensation process do the stars and the giant black hole light up? The unique observation of a distant quasar by Weidinger et al., reported in this issue, offers fresh insight.

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تاریخ انتشار 2004