NASA‘s James Webb Space Telescope will be used to study black-hole powered ‘quasars, bright objects that can emit energy more powerful than all stars in a galaxy.
The tennis-court sized infrared observatory was launched from French Guiana on Christmas Day 2021, finally arriving at its final destination, the second Lagrange point between Earth and the Sun, on January 24, 2022.
During its decade or more in orbit, Webb will be used by teams of astronomers to study a wide variety of celestial phenomena, from exoplanets to black holes.
Among its first targets will be quasars, incredibly bright objects that are powered by a black hole, and ranging in mass from millions, to tens of billions times the sun.
These objects are also known as active galactic nucleus, found in the heart of galaxies alongside supermassive black holes, allowing them to emit energies in the trillions of electron volts, and exceed the output of all stars in the galaxies.
In one of the first rounds of scientific observations, astronomers using Webb will ‘ examine what part quasars play in galaxy evolution during these early times.’
This will give them insight into how the early universe formed, including a look at the gas in the space between the galaxies billions of years in the past.
NASA’s James Webb Space Telescope will be used to study black-hole powered ‘quasars, bright objects that can emit energy more powerful than all stars in a galaxy
The tennis-court sized infrared observatory was launched from French Guiana on Christmas Day 2021, finally arriving at its final destination, the second Lagrange point between Earth and the Sun, on January 24, 2022
Webb is able to peer further into the history of the universe than any space telescope before it, in part due to its position a million miles from the Earth.
It has a very high resolution infrared instrument on board, making it extremely sensitive to very low levels of light – perfect for studying gas surround quasars.
Scientists studying quasars with Webb will examine their properties, as well as that of their host galaxies, and how they are interconnected during the first stages of galaxy evolution in the very early universe.
The team will also use the quasars to examine the gas in the space between galaxies, particularly during the period of cosmic reionization, which ended when the universe was very young.
It is able to d this as a result of the light from these distant objects taking billions of years to reach the telescope – so it is seeing the light as it was emitted near the dawn of everything we know.
‘All these quasars we are studying existed very early, when the universe was less than 800 million years old, or less than 6 per cent of its current age,’ said Santiago Arribas, from the Center for Astrobiology in Madrid, Spain.
Webb is able to peer further into the history of the universe than any space telescope before it, in part due to its position a million miles from the Earth
‘So these observations give us the opportunity to study galaxy evolution and supermassive black hole formation and evolution at these very early times.’
Light from these ancient objects has been stretched by the expansion of space – also known as cosmological redshift.
The farther the light has to travel, the more it is redshifted – and the light from the early universe is stretched so much it is shifted into the infrared when it gets to Earth. This is just the frequency James Webb was designed to observe.
The quasars the team will study are not only among the most distant in the universe, but also among the brightest, with the highest black hole masses, and highest accretion rates – the speed material falls into the black hole itself.
‘We’re interested in observing the most luminous quasars because the very high amount of energy that they’re generating down at their cores should lead to the largest impact on the host galaxy by the mechanisms such as quasar outflow and heating,’ said Chris Willott.
He is a research scientist at the Herzberg Astronomy and Astrophysics Research Centre of the National Research Council of Canada (NRC) in Victoria, British Columbia and the Canadian Space Agency’s Webb project scientist.
Webb is a joint project of NASA, the European Space Agency and the Canadian Space Agency.
‘We want to observe these quasars at the moment when they’re having the largest impact on their host galaxies,’ said Willott.
As matter is accreted by the supermassive black hole, an enormous amount of energy is released, which heats and pushes the surrounding gas outwards.
This then generates strong outflows, tearing across interstellar space like a giant tsunami, in turn causing havoc for its host galaxy.
Experts believe these outflows play a vital role in the evolution of galaxies, as the gas in the expulsions is removed from the galaxy, star formation decreases.
In some cases, outflows are so powerful and expel such large amounts of gas that they can completely halt star formation within the host galaxy.
Scientists also think that outflows are the main mechanism by which gas, dust and elements are redistributed over large distances within the galaxy or can even be expelled into the space between galaxies – the intergalactic medium.
It has a very high resolution infrared instrument on board, making it extremely sensitive to very low levels of light – perfect for studying gas surround quasars
Among its first targets will be quasars, incredibly bright objects that are powered by a black hole, and ranging in mass from millions, to tens of billions times the sun
This may provoke fundamental changes in the properties of both the host galaxy and the intergalactic medium, and this is what the team hope to explore.
They want to go back 13 billion years, when the universe was less than a billion years old, and look at the neutral gas between galaxies – which made it appear opaque.
This neutral gas became ionized over hundreds of millions of years, making it transparent to ultraviolet light. Known as the Era of Reionization.
What led to this period is unclear, and is something astronomers hope Webb will be able to answer, delving deeper into the universe than ever before.
Using the quasars as a background light source, the team will be able to get a better view of the gas that sits between the Earth and the quasar itself.
That gas absorbs the quasar’s light at specific wavelengths, and the team can look for absorption lines in the gas to learn more about the ionization process.
The brighter the quasar is, the stronger those absorption line features will be in the spectrum, and by determining whether the gas is neutral or ionized, scientists will learn how neutral the universe is and how much of this reionization process has occurred at that particular point in time.
‘If you want to study the universe, you need very bright background sources. A quasar is the perfect object in the distant universe, because it’s luminous enough that we can see it very well,’ said team member Camilla Pacifici.
Pacifici is is affiliated with the Canadian Space Agency but works as an instrument scientist at the Space Telescope Science Institute in Baltimore.
‘We want to study the early universe because the universe evolves, and we want to know how it got started,’ the researcher added.
They will look at the light from the quasars, in search of ‘metals’ – which is any element heavier than hdyrogen and helium, formed in the first stars and galaxies.
These ‘metals’ would have been expelled in the massive outflows and should be visible within the sweeping gas between the quasar the Earth.
The team plans to measure the generation of these first ‘metals,’ as well as the way they’re being pushed out into the intergalactic medium by these early outflows.
