Modern astronomy is now taking the many individual observational tools and combining them. In the past, astronomers worked at a particular wavelength, such as radio, optical or X-ray. Observing primarily at one wavelength naturally led these separate communities to have a skewed view of the universe.
The physics that drives the evolution of galaxies and finally bakes our own Milky Way is complicated. By combining observations from many wavelengths of the same galaxy into a coherent picture, we can better understand what’s happening and which processes are important. For example, a galaxy might look ordinary in optical light, but high energy X-rays betray the fact that its central black hole is feeding and injecting energy back into the galaxy.
The COSMOS field now has amazing multiwavelength coverage (“panchromatic” is the fashionable term these days) as almost all of the major observatories on earth and in space have observed it. Now, the COSMOS team are able to view galaxies in their entirety and puzzle out just how they form and evolve.