Astronomy and Astrophysics – Astrophysics
Scientific paper
2004-08-25
Astrophys.J. 617 (2004) 867-878
Astronomy and Astrophysics
Astrophysics
30 pages, 8 figures. Accepted for publication in ApJ (20 November 2004, vol 616 issue)
Scientific paper
10.1086/424890
We have formed ``composite spectra'' by combining the integrated-light spectra of individual galaxies in 8 intermediate-redshift and 12 low-redshift clusters of galaxies. Because these composite spectra have much higher signal-to-noise ratios than individual galaxy spectra, they are particularly useful in quantifying general trends in star formation for galaxy populations in distant clusters, z > 0.3. By measuring diagnostic features that represent stellar populations of very different ages, a grand-composite spectrum can reflect the fractions of those populations as accurately as if excellent spectral measurements were available for each galaxy. Measuring the equivalent widths of spectral features in composite spectra is especially well-suited for comparing cosmic variance of star formation in clusters at a given redshift, or comparing clusters over a range of redshifts. When we do this we find that [O II] emission and especially Balmer absorption is strong in each of our intermediate-redshift clusters, and completely separable from a sample of 12 present-epoch clusters, where these features are weak. Specifically, we show by comparing to the H-delta strengths of present-epoch populations of continuously star-forming galaxies that the higher-redshift samples must contain a much higher fraction of starburst galaxies than are found today in any environment.
Jr.
Couch Warrick
Dressler Alan
Ellis Richard
Oemler Augustus
No associations
LandOfFree
Studying The Star Formation Histories of Galaxies in Clusters from Composite Spectra does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Studying The Star Formation Histories of Galaxies in Clusters from Composite Spectra, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Studying The Star Formation Histories of Galaxies in Clusters from Composite Spectra will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-475771