(Not fully alliterative, but it’s the best I can do after driving 6 hours today.)

The halos of galaxies are best known for harboring dark matter, but they also contain stars. Only a tiny fraction of the total stars in a galaxy are in the halo, so usually they’re hard to spot, but astronomers are realizing they can contribute a significant amount to the total light profile. In particular, a group of researchers using the Spitzer infrared space telescope has determined that much of the infrared haze in the sky is due to galaxies that formed in the early Universe—including their halo stars.

However, the earliest stars and galaxies should contribute to the total infrared glow of the Universe, known as the cosmic near-infrared background (CNIB). (“Near-infrared” refers to wavelengths closest to visible light in the electromagnetic spectrum; in this case, the study was in the 1 to 5 micron range.) Much of the haze in the CNIB is from the Milky Way and known galaxies, but a significant portion is not associated with any obvious sources. Astronomers have postulated it must originate in either to dwarf galaxies (which are too small to be seen at significant distances) or faint galaxies from the early Universe. [Read more….]