NASA’s Webb Telescope looks back in time and uses quasars to reveal secrets of the early universe
Quasars outshine all the stars in their host galaxies combined and are among the brightest things in the universe. These bright, distant, active supermassive black holes make up the galaxies in which they live. Soon after launch, scientists will use Webb to study six of the brightest and most distant quasars, along with their host galaxies, in the very young universe. They will investigate the role quasars played in the evolution of galaxies in these early times. The team will also use quasars to study gases in intergalactic space in the infant universe. Only with Webb’s extreme low-light sensitivity and excellent angle resolution will this be possible.
Quasars are extremely bright, distant, and energetic black holes, with a mass of millions to billions of times the mass of the Sun. They are usually found in the centers of galaxies, feeding on falling matter and unleashing fantastic outpourings of radiation. One of the brightest objects in the universe, quasar light collectively illuminates all the stars in its host galaxy, and their rays and winds make up the galaxy they’re in.
Shortly after its launch later this year, a team of scientists will train NASA’s James Webb Space Telescope on six of the most distant and brightest quasars. They will study the properties of these quasars and their host systems, and how they are interconnected during the early stages of galactic evolution in the very early universe. The team will also use quasars to explore gas in intergalactic space, especially during the cosmic reionization period, which ended when the universe was very young. They achieve this with Webb’s extreme low-light sensitivity and superb angular resolution.
Webb: A Visit to the Young Universe
As Webb looks into the depths of the universe, he is actually looking back in time. The light from these distant quasars began its journey to Webb when the universe was very young and took billions of years to reach. We will see things as they were long ago, not as they are now.
“All of these quasars that we study existed very early, when the universe was less than 800 million years old, or less than 6 percent of its current age. Thus, these observations give us the opportunity to study the evolution of galaxies and the formation of galaxies. And the evolution of supermassive black holes in These early times.Team member Santiago Arribas, Research Professor in the Department of Astrophysics at the Center for Astrobiology in Madrid, Spain, explained “a lot.” Arribas is also a member of Webb’s Near-Infrared Spectrograph (NIRSpec) Instrument Science Team.
The light from these very distant objects has been stretched due to the expansion of space. This is known as the cosmic redshift. The further away the light, the greater the redshift. In fact, visible light from the early universe is stretched so much that it turns into infrared radiation when it reaches us. With a suite of instruments tuned for infrared, Webb is ideally suited for studying this type of light.
Study of quasars, their galaxies, their host environments, and strong currents
The quasars the team will study are not only some of the most distant in the universe, but also some of the brightest. These quasars typically have the highest mass of black holes, and they also have the highest accretion rates—the rates of matter falling into black holes.
“We are interested in observing the brightest quasars because the very high amount of energy they generate in their cores should lead to the greatest impact on the host galaxy through mechanisms such as quasar flux and heating,” Chris said. Willott, a research scientist at the National Research Council (NRC) of Canada’s National Research Council (NRC) Astronomy and Astrophysics Research Center in Victoria, British Columbia. Willott is also a Webb Project Scientist at the Canadian Space Agency. “We want to observe these quasars when they have the greatest impact on the host galaxies.”
When matter accumulates through the supermassive black hole, a huge amount of energy is released. This energy heats up and pushes the surrounding gas outward, creating powerful outflows that rip through interstellar space like a tsunami, causing chaos in the host system.
Watch how jets and winds from a supermassive black hole affect the host galaxy – and into space hundreds of thousands of light-years away over millions of years. Credit: NASA, ESA, and L. Hustak (STScI)
Outflows play an important role in the evolution of galaxies. Gas creates stars, so when gas is removed due to outflow, the rate of star formation decreases. In some cases, the outflows are so powerful that they emit so much gas that they can completely stop star formation in the host system. Scientists also believe that outflows are the main mechanism by which gas, dust, and elements are redistributed over great distances within the galaxy or even can be expelled into intergalactic space – the intergalactic medium. This can lead to fundamental changes in the properties of both the host galaxy and the intergalactic medium.
Exploring the properties of intergalactic space during the era of reionization
More than 13 billion years ago, when the universe was very young, the landscape was far from clear. Neutral gas between galaxies has made the universe opaque to some types of light. Over hundreds of millions of years, the neutral gas in the intergalactic medium has become charged or ionized, making it transparent to ultraviolet light. This period is called the era of reionization. But what led to the reionization that created the “obvious” conditions that are detected in most of the universe today? Webb will go to space to gather more information about this major transformation in the history of the universe. The observations will help us understand the era of reionization, one of the most important frontiers of astrophysics.
The team will use quasars as backlight sources to study the gas between us and the quasar. This gas absorbs quasar light at specific wavelengths. Using a technique called imaging spectroscopy, they look for absorption lines in the interfering gas. The brighter the quasar, the stronger the absorption line in the spectrum. By determining whether the gas is neutral or ionized, scientists learn how neutral the universe is and how much this reionization process is taking place at that very moment.
The James Webb Space Telescope will use an innovative instrument called the Integrated Field Unit (IFU) to capture images and spectra simultaneously. This video provides a basic overview of how IFU works. Credit: NASA, ESA, CSA, and L. Hustak (STScI)
“If you want to study the universe, you need very bright background sources. A quasar is the ideal thing in the distant universe because it is light enough,” said team member Camilla Pacifici, who is affiliated with the Canadian Space Agency but works as an instrument scientist at the Space Telescope Science Institute. We can see it very well.In Baltimore.“We want to study the early universe because the universe is evolving, and we want to know how it started.”
The team will analyze the light from the quasars using NIRSpec to search for what astronomers call “metals,” elements heavier than hydrogen and helium. These elements formed in the first stars and first galaxies and were expelled by outflows. The gas moves from the galaxies in which it was originally located to the intergalactic medium. The team plans to measure the generation of these first “metals,” as well as the way they are being pushed into the intergalactic medium by this early flow.
The power of the web
Webb is a very sensitive telescope that can detect very low light levels. This is significant, because while quasars are intrinsically very bright, the quasars this team will observe are among the most distant objects in the universe. In fact, they are so far away that the signals that Webb will receive are very, very low. Only with remarkable Web sensitivity can this science be accomplished. Webb also provides excellent angular resolution, allowing the quasar’s light to be separated from the host galaxy.
The quasar programs described here are: Guaranteed time notes involving the spectral capabilities of NIRSpec.
The James Webb Space Telescope will be the world’s premier space science observatory when it launches in 2021. Webb will solve the mysteries of our solar system, look beyond to distant worlds around other stars and explore the mysterious structures, origins of the universe and our place in it. Webb is an international program led by NASA with its partners ESA (European Space Agency) and the Canadian Space Agency.
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