This is an artistic concept of a galaxy with a bright quasar star in the center. A quasar is a very bright, distant and active supermassive black hole with a mass of millions to billions of times the mass of the sun. One of the brightest things in the universe is that the light from a quasar is superior to the light from all the stars in its host galaxy combined. Quasars feed on falling matter and unleash streams of wind and radiation, forming the galaxies in which they reside. Using Webb’s unique abilities, scientists will study six of the most distant and bright quasars in the universe. Credit: NASA, ESA and J. Olmsted (STScI)
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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. Shortly 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 gas in intergalactic space in the baby universe. Only with Webb’s extreme low-light sensitivity and excellent angular resolution would this be possible.
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Quasars are extremely bright, distant, active black holes with a mass of millions to billions of times the mass of the Sun. Usually located in the centers of galaxies, they feed on falling matter and unleash fantastic streams of radiation. One of the brightest things in the universe, quasar light collectively illuminates all the stars in its host galaxy, and its rays and winds make up the galaxy in which it resides.
Shortly after 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 period of cosmic reionization, which ended when the universe was very young. They will achieve this with Webb’s extreme low-light sensitivity and impressive angular resolution.
(Click the image to see the full diagram.) More than 13 billion years ago, during the Age of Reionization, the universe was a very different place. The intergalactic gas was too opaque for energetic light, making young galaxies difficult to see. What caused the universe to become completely ionized or transparent, ultimately leading to the “obvious” conditions detected in most of the universe today? The James Webb Space Telescope will dig deeper into space to gather more information about things that existed during the era of reionization to help us understand this important shift in the history of the universe. Credit: NASA, ESA and J.Kang (STScI)
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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 it. 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 evolution of supermassive black holes in these early times. A lot,” explained team member Santiago Arribas, research professor at the Astrophysics Department of the Center for Astrobiology in Madrid, Spain. Arribas is also a member of Webb’s Near-Infrared Spectrograph (NIRSpec) Instrument Science Team.
(Click image to view full diagram.) The Universe is expanding, and this expansion stretches light traveling through space in a phenomenon known as cosmic redshift. The greater the redshift, the greater the distance the light travels. As a result, telescopes equipped with infrared detectors are needed to see light from the first and most distant galaxies. Credit: NASA, ESA and L. Hustak (STSci)
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The light from these very distant objects has been stretched by 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 range of instruments tuned for infrared, Webb is ideally suited to study this type of light.
The study of quasars, their galaxies, their host environments and their powerful 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 usually have the highest mass black holes, and they also have the highest accretion rates — the rates at which material falls 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 flow and heating,” Chris said. Willott, a research scientist at the Herzberg Astronomy and Astrophysics Research Center of the National Research Council (NRC) of Canada in Victoria, British Columbia. Willott is also the Webb Project Scientist of the CSA. “We want to observe these quasars when they have the greatest impact on the host galaxies.”
When matter accumulates through the supermassive black hole, an enormous amount of energy is released. This energy heats up and pushes the surrounding gas out, creating powerful outflows that rip through interstellar space like a tsunami, wreaking havoc in the host system.
Watch as jets and winds from a supermassive black hole affect the host galaxy — and 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 fuels star formation, 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 such large amounts of 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 can even 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. The 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 Age of Reionization. But what led to the reionization that created the “obvious” conditions detected in most of the universe today? Webb will go into 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 in 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. And the brighter the quasar, the stronger those absorption line features in the spectrum. By determining whether the gas is neutral or ionized, scientists learn how neutral the universe is and the extent to which this reionization process occurs at that particular moment.
The James Webb Space Telescope will use an innovative instrument called an Integrated Field Unit (IFU) to simultaneously capture images and spectra. This video gives a basic overview of how the 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 perfect thing in the distant universe because it’s 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. So 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 look 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 out of the galaxies in which it was originally located and into the intergalactic medium. The team plans to measure the generation of these first “metals,” as well as the way they are pushed into the intergalactic medium by this early outflow.
web power
Webb is a very sensitive telescope that can detect very low light levels. This is important, 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 Webb will receive are very, very low. Only with Webb’s remarkable sensitivity can this science be achieved. Webb also offers 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 and 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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