New research has given a more profound knowledge into emission line systems, used in several ongoing and upcoming surveys, to enable us to additionally comprehend the piece the destiny of the universe.
The image shows nearby emission line galaxies NCG 4038 - 4039. The pink parts in this image are showing the light from the gas heated by newly formed stars.
Credit: NASA, ESA and The Hubble Heritage (STScl/AURA)-ESA/Hubble Collaboration.
As young stars are very bright, galaxies with a strong star formation can be visible further back in cosmic time. These are the two characteristics that make emission line galaxies excellent cosmological tracers for a long time span.
However, current emission line galaxy samples are small and their characteristics are not well understood. Computational patterns are the only way to attempt to understand all the processes intertwined in the formation and evolution of these galaxies.
Next summer, the SDSS-IV/eBOSS survey is expected to have the first cosmological results from these tracers. In the coming years, the Dark Energy Survey Instrument (DESI) will expand this usage of emission line galaxies as cosmological tracers.
The DESI will see their first light in 2019 and it will measure the spectra of 35 million galaxies, which is eight times more than the current SDSS has proved. In 2021, Euclid will start collecting spectra for 50 million sources, solely focusing on emission line galaxies.