The very limited role of evolution for redshifts below unity was to some extent contravened by stron

The very limited role of evolution for redshifts below unity was to some extent contravened by stron

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
The very limited role of evolution for redshifts below unity was to some extent contravened by strong claims of color evolution of radio galaxies at redshifts z =1 and larger, and interpretation of counts in both color and magnitude for faint galaxies. If the most powerful radio galaxies, seen to large redshift, are to be identified with normal elliptical galaxies seen at more recent epochs, and if their colors are generally dominated by starlight and not scattered nonthermal radiation, their properties are barely consistent with Hamilton's results. Many of these objects show spectacular levels of star formation, both in emission lines and in the detailed shape of their continua (Chambers and McCarthy 1990 ApJLett 354, L9). A first comparison of the emitted-UV spectra of low-redshift radio galaxies (from IUE) with those at high redshift has been done by Keel and Windhorst (1991 ApJ 383, 135). The UV upturn below about 1400 Å is ubiquitous in low-redshift objects, so much so as to suggest a connection between radio sources and Gyr-old starbursts, and lacking in high-redshift objects. This is consistent with the idea that it requires a few Gyr to produce evolved hot stars, so high-redshift galaxies are seen while too young to have any such stars. The composite spectrum shown by Chambers and McCarthy (190 ApJL 354, L9) indeed shows absorption features from a very
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 2

The very limited role of evolution for redshifts below unity was to some extent contravened by stron

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online