Engineering topics
Publications and source records attributed to Ridgway, S. E..
We discuss the results in light of the cooling flow and the merger/interaction scenarios for triggering and fuelling AGN in clusters, but find that the data do not point unambiguously to neither of the two.
During the course of the Hawaii K-band (2.1 micrometer) survey we have detected a compact object, Hawaii 167, lying at a redshift of 2.33, in which are seen both low- and high-ionization absorption lines. In the near-infrared we see broad H alpha emission at a redshift of 2.35 but do not detect the other Balmer lines, (O II) lambda 3727, or (O III) lambda 5007. The absence of strong Mg II or C IV emission in the rest ultraviolet suggests that, at these wavelengths, we may be seeing a poststarburst galaxy rather than a quasar. Indeed, this class of object may be common enough to represent a major episode of galaxy formation, possibly the formation of the spheroids. However, Q0059-2735, the most extreme member of the class of Mg II absorbing broad absorption line quasars, is very similar to the present object, and there may be an evolutionary sequence or some other close connection between Hawaii 167 and the broad absorption line quasars.
We report the discovery of two galaxies with (I-K) approximately 6.5 lying near the line of sight to the z = 3.790 quasar PC 1643+4631 A. Based on the spectral energy distributions and angular extents of the objects we suggest that the most likely interpretation is that they are elliptical galaxies lying at z approximately 2.4. The existence of such evolved objects at this redshift would imply a current age of the universe substantially in excess of 1.0 x 10(exp 10) yr for q(sub 0) = 0.02, and 1.9 x 10(exp 10) yr for q(sub 0) = 0.5. It would also imply that at least some large luminous galaxies were already fully formed at z greater than 6.