Astronomers have published findings of a study in Astrophysical Journal Letters wherein they have revealed a new way to unlock the mysteries of how the first galaxies formed and evolved using halo of young galaxy.
For the study researchers used new capabilities at W. M. Keck Observatory on Maunakea, Hawaii to examine Q2343-BX418, a small, young galaxy located about 10 billion light years away from Earth. Astronomers say the distant galaxy is an analog for younger galaxies that are too faint to study in detail, making it an ideal candidate for learning more about what galaxies looked like shortly after the birth of the universe. BX418 is also attracting astronomers’ attention because its gas halo is giving off a special type of light.
Astronomers used one of the observatory’s newest instruments, the Keck Cosmic Web Imager (KCWI), to perform a detailed spectral analysis of BX418’s gas halo; its properties could offer clues about the stars forming within the galaxy.
The halo is where gas enters and exits the system. The gas surrounding galaxies can fuel them; gas from within a galaxy can also escape into the halo. This inflow and outflow of gas influences the fate of stars.
The study adds detail and clarity to the image of the galaxy and its gas halo that was not possible before; the instrument is specifically engineered to study wispy currents of faint gas that connect galaxies, known as the cosmic web.
The power of KCWI, combined with the Keck telescopes’ location on Maunakea where viewing conditions are among the most pristine on Earth, provides some of the most detailed glimpses of the cosmos.
The team used KCWI to take spectra of the Lyman alpha emission of BX418’s halo. This allowed them to trace the gas, plot its velocity and spatial extent, then create a 3-D map showing the structure of the gas and its behavior.
The team’s data suggests that the galaxy is surrounded by a roughly spherical outflow of gas and that there are significant variations in the density and velocity range of this gas.
Now that the team has discovered a new way to learn about the properties of the gaseous halo, the hope is that further analysis of the data they collected and computer simulations modeling the processes will yield additional insights into the characteristics of the first galaxies in our universe.