New research has provided a deeper insight into emission line galaxies, used in several ongoing and upcoming surveys, to help us further understand the composition and fate of the Universe.
Lead author of the study, Dr Violeta Gonzalez-Perez from the University’s Institute of Cosmology and Gravitation, said: “Galaxies are cosmic lanterns that show small patches of cosmic history, informing us of the changes in the space-time fabric of the Universe. The strong formation of new stars in galaxies leave a characteristic imprint in their spectra that allows for a precise determination of their distance.
“Moreover, 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 modelling is the only way to attempt to understand all the processes involved in the formation and evolution of these galaxies.
Astronomers from the the world-leading Institute of Cosmology and Gravitation (ICG) explored the characteristics of emission line galaxies through experiments on DiRAC’s (Distributed Research utilising Advanced Computing) national supercomputing facility at Durham University.
They then compared their results with the expectations from the SDSS-IV/eBOSS surveys and Dark Energy Spectroscopic Instrument (DESI). Both surveys aim to measure the effect of dark energy on the expansion of the Universe.
Dr Gonzalez-Perez said: “This comparison will improve our understanding of galaxy formation and evolution and allow scientists to benefit from a more realistic model for the mechanisms that produce emission line 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. The ICG is involved in both surveys.
The study is published in the Monthly Notices of the Royal Astronomical Society.
Source: University of Portsmouth [December 21, 2017]