Q2343-BX418, a young stellar galaxy located about 10 billion light-years from Earth, is surrounded by a huge gashalo, according to new research. This halo spans 75,000 light-years on each side of the galaxy disk and is about ten times the size of the galaxy itself.
The gashalo around this galaxy emits a special kind of light, the Lyman alpha emission. This emission acts as an indicator of the gas, as its photons are absorbed and re-emitted by hydrogen in the halo, allowing astronomers to study the movements and spatial extent of the gas.
"In recent years we have learned that the gaseous halos surrounding the galaxies glow with Lyman alpha emission," Dr. Dawn Erb, astronomer at the University of Wisconsin-Milwaukee.
"There are many different theories about what this Lyman-alpha emission produces halos of galaxies, but at least part of it is probably due to the fact that light, which was originally created by star formation in the galaxy, is due to gas in the halo is absorbed and emitted again. "
Dr. Erb and her colleagues used the Keck Cosmic Web Imager (KCWI), a vast field that recently showed gas halo at the Keck II Telescope at the WM Keck Observatory on Maunakea, Hawaii, a limited, integrated field spectrograph for performing a detailed spectral analysis of Q2343-BX418 ; its properties could provide clues to the stars that form within the galaxy.
"Most of the ordinary matter in the universe does not have the shape of a star or planet, but gas, and most of the gas does not exist in galaxies, but around and between them," Dr. Erb.
"The halo is the place where gas enters and exits the system, and the gas that surrounds galaxies can fuel it, and gas from a galaxy can also escape into the halo Gas affects the fate of stars. "
" The influx of new gas into a galaxy provides fuel for the formation of new stars, while gas outflows limit the ability of a galaxy to form stars by removing gas, so understanding the complex Interactions in this gaseous halo are the key to finding out how galaxies form and evolve stars. "
Astronomers used the KCWI instrument to record spectra of the Lyman alpha emission from the Q2343 BX418 halo. This allowed them to track the gas, visualize its velocity and spatial extent, and then create a 3D map showing the structure of the gas and its behavior.
The new data suggests that the galaxy is surrounded by an approximately spherical gas outlet that there are significant differences in the density and velocity range of this gas.
"This analysis is the first of its kind. Since it has only been tested on one galaxy, other galaxies need to be examined to see if these results are typical," said Dr. Erb.
The results were published in the July 24, 2018 issue of Astrophysical Journal Letters (arXiv.org preprint)
Dawn K Erb et al. . 2018. Kinematics of extended Lyα emission in a low mass galaxy with low metallicity at z = 2.3. ApJL 862, L10; doi: 10.3847 / 2041-8213 / aacff6