Astronomer Alan Dressler
Hot on the trail of the first galaxies in the universe
What did the universe look like in its toddler years? To find out, astronomer Alan Dressler of the Carnegie Institution of Washington and his team are training some of the world’s largest telescopes on a small swath of sky in the constellation Sextans. Their aim is to detect “Lyman-alpha emitters,” distant gas clouds enclosing primordial stars. The blobs hail from a crucial moment when those first stars flooded the cosmos with energy, setting off a chain of events that led to the formation of modern galaxies. Last year Dressler’s colleague Masami Ouchi found the king of the blobs: Nicknamed Himiko, it is 55,000 light-years in diameter, making it the largest object ever seen so early in the universe. Dressler spoke with DISCOVER about what it all means.
Why are you interested in what happened 12 billion years ago?
Our research program started with galaxies: Why are there so many different types, what are their histories, and how did we get the structures we see today—spiral, elliptical, and so forth? Why are they so different? We have a very tentative grasp on that.
Our research program started with galaxies: Why are there so many different types, what are their histories, and how did we get the structures we see today—spiral, elliptical, and so forth? Why are they so different? We have a very tentative grasp on that.
How did your Carnegie colleague find Himiko?
The technique by which we’re seeing this is Lyman-alpha emission. The light comes out in the ultraviolet, then there’s this big redshift [as the light is stretched by the expansion of the universe], which puts it in the more detectable, far-red part of the spectrum. Himiko came out of a survey of Lyman-alpha objects. Out of all those things that Masami was doing, this rather extraordinary object stood out.
The technique by which we’re seeing this is Lyman-alpha emission. The light comes out in the ultraviolet, then there’s this big redshift [as the light is stretched by the expansion of the universe], which puts it in the more detectable, far-red part of the spectrum. Himiko came out of a survey of Lyman-alpha objects. Out of all those things that Masami was doing, this rather extraordinary object stood out.
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