High Redshift Emission-Line Galaxies

Imaging surveys from planetary nebula in other galaxies rely on detecting the extremely bright [O III] 5007 emission line. But not all strong emission-line objects are planetary nebulae. At redshifts near pi (i.e., z = 3.14), the Ly-alpha line of hydrogen is shifted into the bandpass of a typical 5007 A filter. The same techniques that can find PN throughout the Local Supercluster can therefore be used to identify and study large samples of high-redshift galaxies.

Ly-alpha Emitters (LAEs) are an incredibly useful probe of the high-redshift universe. To emit such large Ly-alpha fluxes, LAEs must be virtually dust free. This suggests that they may be galaxies in the act of formation. Moreover, their strong emission allows us to study not only the brightest galaxies, but faint objects as well. Finally, by measuring how the clustering properties of LAEs evolve with time, we can probe both galaxy formation the expansion history of the universe. In other words, the evolution of dark energy!

For further information check out our

Publications on the subject.

The Hobby-Eberly Telescope Dark Energy Experiment (HETDEX)

Web page by Robin Ciardullo ( rbc@astro.psu.edu )
Department of Astronomy and Astrophysics
Penn State University