CIBER-2 will now make measurements in six wavelengths, giving an even more precise understanding of the diffuse infrared glow in our skies. CIBER-2 can distinguish between light that comes from the very first stars and black holes and light from stray stars outside of galaxies. Light from the first stars and black holes that formed in the universe should have a characteristic spectrum of colors that is caused by the absorption of ultraviolet light by the fog of intergalactic hydrogen in the early universe. That hydrogen fog has since lifted, and therefore it does not affect the spectrum of stray stars that formed more recently.
The CIBER-2 mission is led by Michael Zemcov, assistant professor of physics and astronomy at Rochester Institute of Technology (RIT) in New York. Zemcov was a senior postdoctoral scholar at Caltech with Bock before joining the faculty of RIT.
“We know that stars outside of galaxies often occur due to tidal stripping from interactions with other galaxies, but the question is how much?” says Zemcov.
“This background glow is the total light produced over cosmic history,” says Bock, who is also a senior research scientist at Jet Propulsion Laboratory (JPL), which is managed by Caltech for NASA. Much of the cosmic infrared background is thought to come from so-called M and K stars, the most common star types in the universe, though there must also be a component from the first stars and black holes to form. “Our method measures the total light emitted over cosmic history, including any sources astronomers might have missed,” says Bock.
The CIBER-2 instrument, like the earlier CIBER instrument it is based on, observes from a sounding rocket—a small suborbital rocket that carries scientific instruments on brief trips into space. Once above Earth’s atmosphere, CIBER-2 surveys a patch of sky about 4 square degrees; for reference, the full moon takes up about half a degree. The sounding rocket takes CIBER-2 up to space altitudes of about 300 kilometers for a 10-minute flight, then returns the instrument back to Earth. This will be done four times over the next five years; the first launch on a NASA Black Brant IX sounding rocket took place late Sunday, June 6 Pacific Time, from the White Sands Missile Range in New Mexico.
The CIBER missions are important precursors to the Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer (SPHEREx) mission; the telescope, targeted to launch in 2024, will survey the sky over two years in 102 wavelengths, allowing more powerful studies of the background. SPHEREx will also help astronomers understand how our universe began and how common the ingredients for life are in young star and planetary systems. Bock who leads the JPL-managed mission, says, “We cut our teeth developing these new techniques on CIBER, but the SPHEREx data to come will take this this science into a new regime.”