NASA's Webb telescope will look back in time and use quasars to uncover the secrets of the early universe

This is the artistic concept of a galaxy with a bright quasar at its center. A quasar is a very bright, distant, and active supermassive black hole that has millions to billions of times the mass of the Sun. Among the brightest objects in the universe, the light from a quasar exceeds that of all the stars combined in its host galaxy. Quasars feed on falling matter and release torrents of wind and radiation, shaping the galaxies in which they reside. Using Webb's unique resources, scientists will study six of the most distant and luminous quasars in the universe. Credit: NASA, ESA and J. Olmsted (STScI)

Shining all the stars in their host galaxies combined, quasars are among the brightest objects in the universe. These bright, distant, active supermassive black holes shape the galaxies in which they reside. Shortly after its launch, scientists will use Webb to study six of the most distant and luminous quasars, along with their host galaxies, in the very young universe. They will examine what role quasars play in the evolution of the galaxy during these early days. The team will also use quasars to study gas in the space between galaxies in the children's universe. Only with Webb's extreme sensitivity to low light levels and its excellent angular resolution will be possible.

Quasars are very bright, distant, and active supermassive black holes that have millions to billions of times the mass of the Sun. Usually located at the center of galaxies, they feed on falling matter and release fantastic streams of radiation. Among the brightest objects in the universe, the light of a quasar surpasses that of all the stars in its host galaxy combined, and its jets and winds shape the galaxy in which it resides.READ Five healthcare professionals died from COVID-19 in the last week

Shortly after its launch later this year, a team of scientists will train NASA's James Webb Space Telescope in six of the most distant and brightest quasars. They will study the properties of these quasars and their host galaxies, and how they are interconnected during the early stages of galaxy evolution in the early universe. The team will also use quasars to examine gas in the space between galaxies, particularly during the period of cosmic reionization, which ended when the universe was very young. They will do so using Webb's extreme sensitivity to low light levels and excellent angular resolution.

More than 13 billion years ago, during the Age of Reionization, the universe was a very different place. The gas between the galaxies was largely opaque to energetic light, making it difficult to observe young galaxies. What allowed the universe to become completely ionized or transparent, which eventually led to the "clear" conditions detected in much of the universe today? The James Webb Space Telescope will look deeply at space to gather more information about the objects that existed during the Age of Reionization to help us understand this important transition in the history of the universe. Credit: NASA, ESA and J. Kang (STScI)

Webb: Visiting the Young Universe

While Webb looks into the depths of the universe, he actually looks 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 arrive. We will see things as they were a long time ago, not as they are today.READ Starliner test flight scheduled for July 30

"All these quasars that we are studying existed very early when the universe was less than 800 million years old, or less than 6% of its current age. Therefore, these observations allow us to study the evolution of the galaxy and the formation and evolution of supermassive black holes in those very ancient times, "explained team member Santiago Arribas, research professor of the Department of Astrophysics of the Center for Astrobiology in Madrid, Spain. Arribas is also a member of Webb's near-infrared spectrography (NIRSpec) scientific team.

The universe is expanding and this expansion extends light traveling through space in a phenomenon known as cosmological redshift. The greater the redshift, the greater the distance traveled by the light. As a result, telescopes with infrared detectors are needed to see light from the oldest and most distant galaxies. Credit: NASA, ESA and L. Hustak (STScI)

The light from these very distant objects has been stretched by the expansion of space. This is known as cosmological redshift. The farther the light has to travel, the more it shifts to red. In fact, the visible light emitted at the beginning of the universe stretches so dramatically that it shifts to the infrared when it reaches us. With its variety of infrared-tuned instruments, Webb is especially suitable for studying this type of light.

Study quasars, their galaxies and host environments, and their powerful outflows.

The quasars the team will study are not only among the most distant in the universe but also among the brightest. These quasars usually have the highest black hole masses and also the highest accretion rates, the rates at which material falls into black holes.

"We are interested in observing the brightest quasars because a large amount of energy they are generating in their cores should lead to the greatest impact on the host galaxy by mechanisms such as outflow and quasar warming," said Chris Willott, a research scientist at the Herzberg Research Centre for Astronomy and Astrophysics at the National Research Council of Canada (NRC) in Victoria. British Columbia. Willott is also a scientist on the Canadian Space Agency's Webb project. "We want to observe these quasars as they are having the greatest impact on their host galaxies."

A great deal of energy is released when the supermassive black hole adds matter. This energy heats up and pushes the surrounding gas out, generating strong flows that travel through interstellar space like a tsunami, wreaking havoc on the host galaxy.

Notice how the jets and winds of a supermassive black hole affect its host galaxy and space hundreds of thousands of light-years away for millions of years. Credit: NASA, ESA and L. Hustak (STScI)

Outflows play an important role in the evolution of the galaxy. The gas feeds the formation of stars, so when the gas is removed due to a leak, the rate of star formation decreases. In some cases, the outflows are so powerful and release large amounts of gas that they can completely stop the formation of stars within the host galaxy. Scientists also think that outflows are the main mechanism by which gas, dust, and elements are redistributed over great distances within the galaxy or can even be ejected into the space between galaxies, the intergalactic medium. This can cause fundamental changes in the properties of the host galaxy and the intergalactic medium.

Image result for NASA's Webb telescope will look back in time and use quasars to uncover the secrets of the early universe

Examining the properties of intergalactic space during the era of reionization

More than 13 billion years ago, when the universe was very young, the vision was far from clear. The neutral gas between the galaxies caused the universe to become opaque to some types of light. For hundreds of millions of years, the neutral gas in the intergalactic medium was 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 "clear" conditions detected in much of today's universe? Webb will deeply analyze space to gather more information about this important transition in the history of the universe. The observations will help us understand the Age of Reionization, which is one of the main frontiers of astrophysics.

The team will use quasars as backlight sources to study the gas between us and the quasar. This gas absorbs light from the quasar at specific wavelengths. Using a technique called imaging spectroscopy, they look for absorption lines in the intermediate gas. The brighter the quasar, the stronger the characteristics of the absorption line in the spectrum. By determining whether the gas is neutral or ionized, scientists will learn how neutral the universe is and how much of this reionization process took place at that particular time.

The James Webb Space Telescope will use an innovative instrument called an integral field unit (IFU) to capture images and spectra at the same time. This video provides a basic description 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 a perfect object in the distant universe because it's bright enough that we can see it very well," said Camilla Pacific, a member of the team, who is affiliated with the Canadian Space Agency but works as an instrument scientist in space. Institute of Telescope Sciences in Baltimore. "We want to study the early universe because the universe evolves and we want to know how it started."

The team will analyze the light from quasars with NIRSpec to look for what astronomers call "metals," which are elements heavier than hydrogen and helium. These elements formed in the first stars and early galaxies and were ejected by spills. The gas leaves the galaxies it was originally in and enters the intergalactic medium. The team plans to measure the generation of these early "metals," as well as how these initial flows push them into the intergalactic medium.

Webb's Power

Webb is an extremely sensitive telescope capable of detecting very low light levels. This is important because, although quasars are inherently very bright, the ones 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 Webb's exquisite sensitivity can this science be achieved. Webb also offers excellent angular resolution, allowing you to separate quasar light from your host galaxy.

The quasar programs described here are Guaranteed Time Observations involving the spectroscopic capabilities of NIRSpec.

The James Webb Space Telescope will be the world's leading space science observatory when it launches in 2021. Webb will solve mysteries in our solar system, see beyond distant worlds around other stars, and investigate the mysterious structures and origins of our universe and ours. place of start. Webb is an international program run by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency.

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