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Hot winds stay in the plane

Article Abstract:

Questions concerning quasars were the focus of discussions at a meeting at the Carnegie Observatories in Pasadena, CA, in Feb 1997. According to current theory, quasars are huge black holes fueled by gaseous accretion disks, the latter containing material that becomes very hot and gleams brightly as it goes down the funnel into the black hole. Measurements of the polarization of quasar light showed that the light they emit becomes polarized if it scatters off surrounding material. The measured spectrum can be divided into polarized and unpolarized parts to offer several views of the same quasar, thus providing an indirect probe of the geometry of quasar outflows.

Radio sources (Astronomy), Radio sources (Astronomical bodies)

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Peering between the clouds

Article Abstract:

The results from a long spectroscopic investigation of the high-redshift quasar Q0302-003 provide further evidence for the existence of a tenuous plasma in intergalactic space at high redshift. Radiation from quasars makes this plasma highly ionized. Q0302-003 shows a clearing, or 'void,' in the Lyman forest of narrow Lyman-alpha absorption lines from hydrogen along its line of sight. This void is not replicated in the He+ absorption, indicating that the He+ opacity is dominated by gas which is more diffuse than the Lyman-forest systems.

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Large size of Lyman-alpha gas clouds at intermediate redshifts

Article Abstract:

The ultraviolet spectra of the quasar pair Q0107-025A and B reveal the presence of four Lyman-alpha lines, which originate from both the objects. The lines are in the redshift range from 0.5 to 0.9 and reveal that the radius of the clouds is not less than 160 per Hubble constant kilo parsecs. The clouds have feeble internal motions consistent with the explanations provided by the conventional models of motion.

Measurement, Red shift, Redshift, Interstellar hydrogen

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