Part of the web of gaseous filaments thought to permeate intergalactic space has been mapped directly for the first time. Two filaments of the web were observed by an international team of astronomers using the Very Large Telescope (VLT) and Keck II telescope. The team’s discovery heralds an important milestone in our understanding of the largest known structures in the universe, paving the way for future studies with even larger telescopes.
First gaining prominence in the late 1990s, the lambda cold dark matter model predicts that over 60% of all baryonic (normal) matter resides within a complex network of hydrogen gas filaments, which spans the entire universe. Galaxies form either when two filaments cross, or if a filament section is particularly dense. After a galaxy is formed, the surrounding filaments feed it with cool gaseous hydrogen.
When filaments are illuminated by ultraviolet light from galaxies, they should emit light by the process of hydrogen fluorescence. This light has been spotted in structures around galaxies, but not further out into intergalactic regions of space.
Sophisticated background subtraction
In this latest study, Hideki Umehata at the RIKEN Cluster for Pioneering Research in Japan and colleagues took a broader approach: observing ...