NASA’s James Webb Space Telescope (JWST) has made an astonishing discovery on cosmic objects from the early universe. The JWST, popularly called Webb, has found a cluster of massive galaxies in the process of forming around an extremely red quasar. The discovery is important because it will help researchers better understand how galaxy clusters in the early universe came together and formed the cosmic web or knot, a network of filaments which astronomers believe forms the basis of the universe.
What is a quasar?
A quasar is a brilliant beacon of intense light from the centre of a distant galaxy that can outshine the entire galaxy and is powered by a supermassive black hole which is feeding on inflating matter, according to NASA. In other words, a quasar is a special type of active galactic nucleus, which is a small and extremely luminous region at the centre of some galaxies.
Active galactic nuclei are now understood to be active supermassive black holes that emit bright jets and winds, and shape their galaxies. When gas falls into the black hole, it emits bright jets and winds, making the quasar bright enough to outshine all the galaxy’s stars.
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What quasar did Webb observe?
Webb explored a quasar that existed 11.5 billion years ago. The quasar is unusually red not just because of its intrinsic red colour, but also because the vast distance of the galaxy from Earth has red-shifted it. Redshift means that the wavelength of light is stretched, as a result of which it appears shifted towards the red part of the spectrum. Since Webb has unparalleled sensitivity to infrared wavelengths, it was perfectly suited to study the galaxy harbouring the red quasar.
The study describing the findings will be published in The Astrophysical Journal Letters.
The quasar observed by Webb is one of the most powerful known galactic nuclei that has been seen at such an extreme distance. The quasar’s extreme emission could cause a “galactic wind”, astronomers had speculated. This galactic wind would push free gas out of its host galaxy and possibly greatly influence future star formation there.
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Webb’s NIRSpec investigated the quasar
Astronomers used Webb’s Near-Infrared Spectrograph (NIRSpec) to investigate the movement of the gas, dust and stellar material in the galaxy. NIRSpec uses a technique called spectroscopy to look at the movement of various outflows and winds surrounding the quasar. Spectroscopy is the study of absorption and emission of light and other radiation by matter, and is used as a tool for studying the structures of atoms and molecules. Since NIRSpec can simultaneously gather spectra across Webb’s whole field of view, instead of just from one point at a time, it enables the telescope to simultaneously examine the quasar, its galaxy and the wider surroundings.
The quasar’s host galaxy was merging with other galaxies
According to NASA, astronomers predicted that the quasar’s host galaxy could be merging with some unseen partner. However, the team was not expecting Webb’s NIRSpec data to clearly indicate that the host galaxy was not merging with just one partner, but at least three more swirling around it. Since NIRSpec gathered spectra over a broad area, the motions of all the surrounding material could be mapped. This resulted in the conclusion that the red quasar was part of a dense knot of galaxy formation.
Significance of the discovery
In a statement released by NASA, astronomer Dominika Wylezalek of Heidelberg University in Germany said there are few galaxy protoclusters (group of galaxies that are beginning to form a cluster) known at this early time, and the new discovery may eventually help astronomers understand how galaxies in dense environments evolve.
The researchers confirmed three galactic companions to the quasar and showed how they are connected using the observations from NIRSpec. There may be more galactic companions to the quasar, archival data from the Hubble Space Telescope has shown.
Team member Andrey Vayner of Johns Hopkins University in Baltimore, Maryland, said the first look at the data quickly revealed clear signs of major interactions between the neighbouring galaxies.
The quasar is one of the densest known areas of galaxy formation
The researchers found that the three confirmed galaxies are orbiting each other at incredibly high speeds. This is an indication that a great deal of mass is present. They are closely packed into the region around the quasar. The researchers believe that this marks one of the densest known areas of galaxy formation in the early universe.
Wylezalek said the team thinks it could be seeing a region where two massive halos of dark matter are merging together.
Next, the team plans to conduct follow-up observations into the unexpected galaxy protocluster, and use it to understand how dense, chaotic galaxy clusters like this one form, and how the active, supermassive black hole at the heart of the galaxy affects it.