Grad Appreciation Week Poster Session Winner, Seth Cohen

On April 30, 2014 by Grad Forum

Congratulations to Seth Cohen, graduate student in the Department of Physics and Astronomy, who was one of four winners of the Graduate Poster Session held recently in Alumni Hall! (Below is a summary of Cohen’s poster.)

Poster Title: Star Formation and Substructure in Galaxy Clusters


Professor in the Department of Computer Science, David Kotz (left), who served as a judge during the Graduate Poster Session, presents the award to Seth Cohen.

When we astronomers look at the entire Universe, we find that galaxies are not scattered randomly. Instead, there are large clumps of galaxies in some areas, long filaments of galaxies connecting these clumps, and gigantic voids where no galaxies exist. I study the largest of these clumps of galaxies, which are called “galaxy clusters.” These clusters can contain anywhere from twenty or thirty galaxies to upwards of a thousand. The galaxies in any particular cluster are all gravitationally bound together and orbit each other in a phenomenally large and energetic environment.

When two or more of these individual clusters (not galaxies!) merge and interact, the galaxies themselves are affected. In particular, the merging process affects how stars form in the galaxies inside these clusters. The question I seek to answer is whether the cluster merging process increases or decreases the formation of stars in galaxies.

To do this, I have used pictures and spectra of tens of thousands of galaxies in hundreds of clusters. Instead of performing my own observations, I use data from ground- and space-based telescopes that, over the last decade, have observed the entire sky and gathered data on millions of galaxies. This data is available for anyone interested to use.

The simplest question I ask is: Do clusters with more merging activity have more star formation than clusters with less merging activity? The simplest answer is: Yes! After studying hundreds of clusters, we find that, on average, more merging is correlated with more star formation. This is exciting, as it lends insight into how stars everywhere form. It also provides another window into learning more about galaxy clusters, which are useful in studying mysterious dark matter and dark energy.

poster summary by Seth Cohen

Cohen, along with the other poster winners, explains his research in this video:

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