But by developing better model spectra and comparing the results with the Keck spectra of Hubble Deep Field galaxies
, astronomers significantly increased the precision.
The authors compare their results for cluster spirals to a small sample of field galaxies
from Zaritsky et al.
"This is the first direct determination of the fraction of field galaxies
in the local Universe that contain active supermassive black holes," said co-author Paul Green of the Harvard-Smithsonian Center for Astrophysics in Cambridge, MA.
The aim of the project is to study age and metallicity gradients and dust extinction in spiral galaxies in clusters and compare the results with what has been found for field galaxies
. They did their first observing run in 2006 for this project.
Color information may also indicate whether many of the Deep Field galaxies
are as compact as they appear or are merely the brightest parts of large, diffuse galaxies, Dickinson adds.
Two additional field galaxies
share a medium-power view with M106.
Meanwhile, Michael Merrifield (University of Nottingham, England) says that analysis of Hubble Deep Field galaxies
indicates that barred spirals were virtually absent until the universe was about half its present age.