Mapping the early universe with NASA’s Webb Telescope

Astronomers and engineers have designed telescopes, in part, to be “time travelers”. The further away an object is, the longer it takes for its light to reach Earth. Looking back in time is one reason why NASA’s upcoming James Webb Space Telescope specializes in collecting infrared light – these longer wavelengths, which were initially emitted by stars and galaxies as ultraviolet light ago. over 13 billion years, they have been extended or displaced into the infrared. light as they traveled towards us through the expanding universe.

Although many other observatories, including NASA’s Hubble Space Telescope, have previously created “deep fields” by looking at small areas of the sky for significant periods of time, the Cosmic Evolution Early Release Science Survey (CEERS), led by Steven L. Finkelstein of the University of Texas at Austin will be the first for Webb. He and his research team will spend just over 60 hours aiming the telescope at a portion of the sky known as the Extended Groth Strip, which was observed as part of the Hubble Near Infrared Deep Extragalactic Legacy Survey, or CANDELS.

“With Webb, we want to make the first galaxy reconnaissance even closer to the big bang,” said Finkelstein. “It is not absolutely possible to do this research with any other telescope. Webb can do remarkable things at wavelengths that have been difficult to observe in the past, on the ground or in space.”

Mark Dickinson of the National Science Foundation’s National Infrared Optical Astronomy Research Laboratory in Arizona, and one of the co-investigators in the CEERS Survey, nods at Hubble while waiting for Webb’s observations. “Surveys like Hubble’s Deep Field have allowed us to map the history of cosmic star formation in galaxies half a billion years from the Big Bang to the present in surprising detail,” he said. “With CEERS, Webb will look even further to add new data to those surveys.”

Delivering the invisible

What was the early universe like? There are certainly many data points, but not enough to create a comprehensive census of their conditions. Additionally, the researchers’ knowledge and assumptions are updated frequently, each time a new in-depth exposition is released. “Every time we look further, we find galaxies earlier and earlier than we thought possible. Conditions in the early universe had to be right for galaxies to form, and they formed and became massive very quickly,” said the Co-investigator of the CEERS Survey. Jeyhan Kartaltepe of the Rochester Institute of Technology in New York.

“The universe was more compact at this time, which means that stars and galaxies could have formed with greater efficiency,” added Finkelstein. “Some models predict that we will find 50 galaxies in earlier times more distant than Hubble can reach, but others predict that we will find only a few. In both cases, the data will help us limit galaxy formation in the early universe.”

The CEERS Survey team hopes to identify a host of distant objects, including the most distant galaxies in the universe, the earliest galaxy mergers and interactions, the first massive or supermassive black holes, and even quasars earlier than previously identified. These “first” potentials are just the beginning of the value of this research: The team, made up of more than 100 researchers from around the world, will sort many objects in the field. “These data will help demonstrate what the structure of the universe was like at various periods,” Finkelstein explained.

Hitting “rewind”

Perhaps the most exciting element of this research is how the team will use the data to discover new findings about an important period in the history of the universe called “The Age of Reionization.” The Big Bang triggered a series of events that led to the cosmic microwave background, the dark ages, the first stars and galaxies, and then to the Age of Reionization. During this period, the gas in the universe became mostly neutral, meaning it was opaque to ultraviolet light, and completely ionized, allowing it to be transparent. Ionization means that the atoms were stripped of their electrons, which ultimately led to the “clear” conditions detected in much of the current universe.

Many questions remain about this unique moment in our universe. For example, what was responsible for converting the gas from neutral to ionized? And how long did it take before the universe became significantly less opaque and much more transparent?

“We believe this happened when ultraviolet light escaped young, forming galaxies,” said Dickinson. “There may be other factors. For example, early accumulation black holes may also have emitted ultraviolet light that eventually helped transform the gas.”

Where galaxies appear in the sky offers another clue. “We will examine the galaxies of the reionization era to see if they are clustered in the same regions or if they are more isolated,” said Kartaltepe. “We have a lot of ideas about what causes galaxies to grow and become more massive, but we need more complete information about these galaxies to fully understand how they initially grew and evolved.”

The presence of galactic mergers or interactions, or the lack of them, will also help the team track environmental conditions during the Age of Reionization. “The CEERS survey will give us clues to how this period unfolded,” adds Dickinson. “We will certainly learn about the galaxies we think are responsible, and we also hope to learn about the ionizing radiation that escaped from them.”

The team has designed the CEERS Survey to provide as much supplemental data as possible for many objectives in this field of vision. They will employ three of Webb’s instruments, in various modes, to obtain images of the Extended Groth Strip, in addition to the spectra. Spectra are invaluable data as they help researchers identify the colors, temperatures, movements, and masses of each target, and provide a much deeper insight into the chemical composition of distant objects.

“That’s the difference with Webb’s near-infrared spectrograph, or NIRSpec,” Dickinson emphasized. “We will open the microhutter slots of the spectrograph to individually observe hundreds of galaxies to obtain their spectra for the first time.”

Starting to build a census

In the months after the initial data is released, CEERS Survey researchers will create and publish new tools and catalogs that any researcher can use to analyze data, including galaxy masses, galaxy shapes, and redshifts. photometric. “With the same set of observations, hundreds of researchers can perform hundreds of scientific experiments,” said Kartaltepe. “We will also find things we didn’t even think to ask, which is one more reason why the CEERS Survey research will be so rewarding. Our hope is that the CEERS Survey will influence future distant galaxy surveys with Webb.” Finkelstein added. “It will also demonstrate to the community that observing with a variety of instruments and modes are very valid ways to increase Webb’s scientific performance.”