New galaxy images reveal a fitful start to the Universe

Image courtesy of SHARDS research. Credit to SHARDS research team
New images reveal details about the origins of the Universe's first stars and structures. This suggests that the Galaxy formed from a chaotic start.

A team of international astronomers from the University of Nottingham (CAB, CSIC–INTA) used data taken from the Hubble Space Telescope and the Gran Telescopio Canarias to study the Frontier Fields. They were able to find and study the faintest galaxies within the near universe. The galaxy's formation was most likely accidental. The journal Monthly Notices of the Royal Astronomical Society (MNRAS) has published the first results.

Astronomers have struggled for decades to answer the question of how and when galaxies first formed. One possibility is that the formation and growth of the first galaxies was gradual, building up an ever larger system. Another possibility is that formation was more rapid and continuous, with short-lived bursts star formation triggered primarily by mergers or enhanced gas accretion.

Pablo G. Prez - Gonzlez, one co-author of the paper and principal investigator behind the international collaboration behind the study, said that galaxy formation can be likened to a car. The first galaxies may have had a "diesel" star-forming engine that slowly added stars to the galaxy, but did not accelerate. It could also turn gas into small stars over long periods of time, making it more efficient. You could also have a jerky formation process, where star formation bursts produce huge stars that disrupt the galaxy's activity and cause it to cease for a time or forever. Every scenario is tied to different processes such as galaxy mergers and the influence of supermassive dark holes. They have an impact on how and when the carbon and oxygen that are vital for our lives, formed.

The astronomers used the gravitational lensing power from some of the Universe's largest galaxy clusters, along with exceptional GTC data from a project called the Survey for high Z Red and Dead Sources. They searched for analogs nearby of the very first galaxies to form in the Universe so they could be studied more closely.

Alex Griffiths, University of Nottingham, was one the leading UK researchers in the study. He explained that without the James Webb Space telescope we can't observe the first galaxies to have ever formed. They are too faint. We searched for similar creatures in the Universe, and we used the most powerful telescopes that we have to dissect them.

Researchers combined the power and capabilities of some of the most powerful telescopes (such as HST or GTC) with "natural telescopes". Co-author of the study is Professor Chris Conselice from the University of Manchester. He said that "some galaxies exist in large groups, which we call clusters. These contain enormous amounts of mass in form of stars but also gas or dark matter. Their mass is so great that they bend spacetime and act as natural telescopes. They are also known as gravitational lenses. They allow us to see distant galaxies at higher brightness and with greater spatial resolution.

The Frontier Field survey began with observations of large clusters that act as gravitational telescopes. It was found that the galaxy formation process was likely to be stop-start, with brief bursts of activity and then lulls. Dr. Griffiths, University of Nottingham, stated that galaxy formation was a slow process, much like a jerky engine. There are periods of increased star formation, followed by quiet intervals. It is unlikely that galaxy mergings played a significant role in the triggering these bursts. We need to look for other causes that increase gas accretion.

We were able find these objects thanks to the SHARDS data of high quality and imaging data from Hubble Space Telescope. This data was used to detect hot gas that has been heated by new stars in small galaxies. The emission lines are the wavelengths at which hot gas emits light, similar to a neon sign. These emission lines can be used to gain insight into the evolution and formation of a galaxy. ".

"The SHARDS Frontier Fields observations made with GTC have provided us with the most detailed data ever obtained for discovering dwarf galaxies via their emission lines," says Prez-Gonzlez. He is also the principal investigator for the GTC SHARDS Frontier Fields program.

Continue reading Image: Hubble discovers a burst in star formation

More information: Monthly Notices of the Royal Astronomical Society Emission Line Galaxies within the SHARDS Frontier Fields I - Candidate Selection, and the Discovery of Bursty Ha Emitters. Information for the Journal: Monthly Notices from the Royal Astronomical Society Emission Galaxies in SHARDS Frontier Fields I - Candidate Selection, and the Discovery of Bursty Ha Emmitters. (2021). DOI: 10.1093/mnras/stab2566