ASTROPHYSICS: Galaxy Evolution: A Dim Future

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Science  17 Jan 2003:
Vol. 299, Issue 5605, pp. 311d-313d
DOI: 10.1126/science.299.5605.311d

Galaxies, the major building blocks of the luminous universe, have evolved with time. However, it has been difficult to follow this evolution by characterizing faraway galaxies, because the morphologies of these distant objects are obscured.

Using the 10-m Keck telescope and adaptive optics, Glassman et al. have succeeding in resolving the disk and the bulge of 10 galaxies at a redshift of 0.5 at infrared wavelengths. The disks are larger and have a higher surface brightness than today's more evolved galaxies (at a redshift of 0). Thus, these less evolved, higher-redshift galaxies (immature galaxies) possess a younger stellar population with more active star formation, and these disks will probably fade and come to resemble today's more evolved galaxies. The bulges show no differences compared to today's galaxies, which is consistent with the model of bulges forming from a uniformly older stellar population and not changing over time. More observations of more galaxies, with improvements such as large telescopes and adaptive optics, will help confirm whether young and active galaxies can look forward to a dim future of fading disks and static halos, or if alternative scenarios such as starbursts or exotic galaxies might liven up the luminous cosmos. — LR

Acknowledgments

Astrophys. J. 581, 865 (2002).

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