A Baby Milky Way

I thought this was pretty interesting. With the help of the Keck Telescope in Hawaii, astronomers were able to obtain spatially resolved images of young galaxies, such as DLA2222-0946, shown above. Young galaxies such as this one will one day grow to become common spiral galaxies, much like our Milky Way. Although they tend to be common, they are important in that they provide insight into the evolution process by which the bulk of galaxies form.

Detecting these young galaxies, and resolving them, seems to be the difficult part. This is because they mainly contain neutral gas, which does not emit any light. So how do astronomers find them? With the help of quasars! As the light from a quasar passes through the gas of these galaxies, absorption spectra can be acquired to determine the presence and contents of the gas.

Because of this, the young galaxies are also termed DLAs, or damp Lyman-alpha absorption systems. From the Rydberg formula we discussed in lecture, this corresponds to m=1 and n=2 absorptions of hydrogen. A simple but useful application of what we have learned thus far.

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