The CIBER experiment or the story of how scientists discovered the second half of the universe

The amazing results of the CIBER suborbital rocket experiment revealed a surplus of radiation in the Universe, which in its intensity is comparable to that of all the galaxies combined. It is assumed that the source of this radiation are single stars, traveling in intergalactic space.

^{Time lapse photo of CIBER rocket launch, launched in 2013 from the launch site of Vallops, Virginia. It was the last of 4 flights CIBER. Suborbital rockets are ideal for fast astronomical observations of the Earth’s atmosphere. The photo shows the work of the first three stages of the Black Brant XII class rocket. Image rights: T. Arai / University of Tokyo.}

The discovery changes the scientists' idea of ​​galaxies - instead of the concept of limited separated star seas, it may be worth considering them as a single ocean in which galaxies stretch for many great distances, connecting with each other and forming one whole.
')
The CIBER (Cosmic Infrared Background Experiment) experiment can solve the problem of the origin of the background infrared radiation that was detected by the Spitzer space telescope. It is still unclear whether the source is individual stars in intergalactic space that are too far away to be seen directly, or the first galaxies of the universe.

In 2007, researchers using the BLAST experiment (Balloon-Borne Large Aperture Submillimeter Telescope) and the Spitzer orbiting telescope, suggested that gas-dust clouds surrounding young galaxies are responsible for the cosmic background infrared radiation. Moreover, 70% of all radiation accounted for galaxies located no closer than 9 billion light years from Earth. The active process of star formation going into them heats the intergalactic gas and dust to a temperature of about 30 K, which is the cause of radiation.

The latest work of scientists on this topic, based on CIBER data, suggests that separate, alone wandering stars are responsible for a substantial part of this radiation. Lead author of the study, published on November 7 in the journal Science, Michael Zemcov (Michael Zemcov) notes:

We think that stars fly into intergalactic space during the collision of galaxies. Recent data confirm that similar emissions caused by tidal forces occur everywhere.

^{Optical instruments CIBER. Two infrared cameras are located in the upper part of the image, two spectrometers are located in the bottom, and the Fraunhofer spectrometer is located in the lower right corner. Photo: Jamie Bock / Caltech.}

Using small unmanned suborbital rockets, ideal for short-term experiments like CIBER, scientists obtained images of infrared radiation with two different wavelengths, shorter than in previous experiments. Due to the fact that our atmosphere also has a significant luminescence in this range, measurements should be carried out outside the atmosphere. During the flight of the rocket along a ballistic trajectory, the cameras took photographs for 7 minutes, then sent data to Earth, where scientists filtered radiation from bright stars, galaxies and any other point sources, including the radiation of the Milky Way itself. As a result, the researchers obtained a distribution map of the fluctuations of the cosmic infrared background radiation, with individual nuclei that are larger than individual galaxies. The brightness of these fluctuations allows us to estimate the overall intensity of the background radiation.

^{Input data processing by CIBER scientists. In the transition to the second stage, the noise is removed from all the stars and galaxies. In the transition to the third, the radiation is “smeared”, so that large-scale structures can be seen. The resulting blurred background does not come from any known star or galaxy. Researchers are sure that it comes from stars in intergalactic space. Image rights: NASA / JPL.}

To the surprise of the CIBER team, the map revealed a significant excess of light in the intergalactic space, comparable to the emission of all the galaxies combined. This unexpected glow had a bluer spectrum, which means that its brightness increased with decreasing wavelength. This suggests that light comes from individual, previously unrecorded, populations of stars that are in intergalactic space, because the emission spectrum of distant galaxies would be much more strongly shifted to a redder region of the spectrum.

^{The images obtained by the CIBER experiment cover large parts of space, representing the infrared radiation emanating from them, at different wavelengths (1.1 microns and 1.6 microns). These are already processed photographs in which noises from all known galaxies are filtered out and a smoothing algorithm is applied, which exposes a large-scale structure. Both photos show the same patterns, proving the fact that the radiation came from the same sources. Image rights: NASA / JPL-Caltech.}

Clarification of James Bock (James Bock), chief investigator of the CIBER experiment:

The radiation is too bright and too shifted to the blue side of the spectrum, so that its source could be the first generation of galaxies. The simplest and most logical assumption, which best explains the measurements, will be that the source of this glow is stars, cut off from their galaxies, whose total radiation intensity exceeds the radiation of all galaxies combined.

Future experiments will be able to test this hypothesis. In the meantime, the CIBER team is working on a more detailed analysis of the background infrared radiation in order to find out how the stars were separated from their galaxies throughout the history of the Universe.

^{The processed photo shows a possible picture of galaxies immersed in an invisible star halo. The results of the CIBER experiment suggest that the total radiation of these stars is comparable to the radiation from all the galaxies combined. Image rights: NASA / JPL-Caltech.}