Nicole Vogt » Satellite Galaxy Populations
We have combined HST V, I and H-band data below to form a color image of a distant galaxy survey field. The central object is a large, edge-on galaxy at a redshift z ~ 0.8, with six small, blue neighbors surrounding it. By comparison with adjoining fields, we can see that the density of the blue objects is far too high around the primary galaxy to be explained as a random superposition of foreground and background objects. Because of this we are confident that they lie at the redshift of the main galaxy, even though they are too faint to be confirmed spectroscopically without a great deal of time and effort on a large telescope (a full night on a 10-meter). They are all about 4 magnitudes fainter than L*, and appear to be within a radius of 50 kpc of the main galaxy.
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We are modeling the formation and evolution of the system through numerical
simulations, to better understand the likelihood and significance of such
early-forming, well-developed companions.