NASA’s Chandra X-ray Observatory detects X-ray emissions from astronomical occasions. Credit score: NASA/CXC & J. Vaughan.
When a star is born or dies, or when every other very energetic phenomenon happens within the universe, it emits X-rays, that are high-energy gentle particles that aren’t seen to the bare eye. These X-rays are the identical sort that doctors use to take photos of damaged bones contained in the physique. However as a substitute of trying on the shadows produced by the bones stopping X-rays inside an individual, astronomers detect X-rays flying by space to get pictures of occasions resembling black holes and supernovae.
Pictures and spectra – charts exhibiting the distribution of sunshine throughout completely different wavelengths from an object – are the 2 important methods astronomers examine the universe. Images tell them what issues appear to be and the place sure phenomena are taking place, whereas spectra tell them how a lot power the photons, or gentle particles, they’re accumulating have. Spectra can clue them in to how the occasion they got here from shaped. When finding out complicated objects, they want each imaging and spectra.
Scientists and engineers designed the Chandra X-ray Observatory to detect these X-rays. Since 1999, Chandra’s information has given astronomers extremely detailed pictures of a few of the universe’s most dramatic occasions.
Stars forming and dying create supernova explosions that ship chemical components out into space. Chandra watches as gas and stars fall into the deep gravitational pulls of black holes, and it bears witness as gasoline that’s a thousand occasions hotter than the Solar escapes galaxies in explosive winds. It could see when the gravity of big plenty of dark matter lure that scorching gasoline in gigantic pockets.
NASA designed Chandra to orbit across the Earth as a result of it will not have the ability to see any of this exercise from Earth’s floor. Earth’s atmosphere absorbs X-rays coming from space, which is nice for all times on Earth as a result of these X-rays can hurt organic organisms. But it surely additionally signifies that even when NASA positioned Chandra on the very best mountaintop, it nonetheless wouldn’t have the ability to detect any X-rays. NASA wanted to ship Chandra into space.
I am an astrophysicist on the Smithsonian Astrophysical Observatory, a part of the Middle for Astrophysics | Harvard and Smithsonian. I’ve been engaged on Chandra since earlier than it launched 25 years in the past, and it’s been a pleasure to see what the observatory can educate astronomers in regards to the universe.
Supermassive black holes and their host galaxies
Astronomers have discovered supermassive black holes, which have plenty ten to 100 million occasions that of our Solar, in the centers of all galaxies. These supermassive black holes are largely sitting there peacefully, and astronomers can detect them by trying on the gravitational pull they exert on close by stars.
However generally, stars or clouds fall into these black holes, which prompts them and makes the area near the black hole emit numerous X-rays. As soon as activated, they’re known as active galactic nuclei, AGN, or quasars.
My colleagues and I needed to higher perceive what occurs to the host galaxy as soon as its black hole turns into an AGN. We picked one galaxy, ESO 428-G014, to have a look at with Chandra.
An AGN can outshine its host galaxy, which signifies that extra gentle comes from the AGN than all the celebrities and different objects within the host galaxy. The AGN additionally deposits a variety of power throughout the confines of its host galaxy. This impact, which astronomers call feedback, is a vital ingredient for researchers who’re constructing simulations that mannequin how the universe evolves over time. However we nonetheless don’t fairly know the way a lot of a task the power from an AGN performs within the formation of stars in its host galaxy.
Fortunately, pictures from Chandra can present essential perception. I exploit computational methods to construct and course of pictures from the observatory that may inform me about these AGNs.
The energetic supermassive black hole in ESO 428-G014 produces X-rays that illuminate a big space, extending so far as 15,000 gentle years away from the black hole. The fundamental picture that I generated of ESO 428-G014 with Chandra data tells me that the area close to the middle is the brightest, and that there’s a giant, elongated area of X-ray emission.
The identical information, at a barely larger decision, reveals two distinct areas with excessive X-ray emissions. There’s a “head,” which encompasses the middle, and a barely curved “tail,” extending down from this central area.
I may also course of the information with an adaptive smoothing algorithm that brings the picture into a fair larger decision and creates a clearer image of what the galaxy appears to be like like. This reveals clouds of gasoline across the vibrant middle.
My group has been in a position to see a few of the methods the AGN interacts with the galaxy. The images show nuclear winds sweeping the galaxy, dense clouds and interstellar gasoline reflecting X-ray gentle, and jets capturing out radio waves that warmth up clouds within the galaxy.
These pictures are instructing us how this suggestions course of operates intimately and measure how a lot power an AGN deposits. These outcomes will assist researchers produce extra lifelike simulations of how the universe evolves.
The following 25 years of X-ray astronomy
The 12 months 2024 marks the twenty fifth 12 months since Chandra began making observations of the sky. My colleagues and I proceed to rely upon Chandra to reply questions in regards to the origin of the universe that no different telescope can.
By offering astronomers with X-ray information, Chandra’s information dietary supplements data from the Hubble Space Telescope and the James Webb Space Telescope to present astronomers distinctive solutions to open questions in astrophysics, resembling the place the supermassive black holes discovered on the facilities of all galaxies got here from.
For this explicit query, astronomers used Chandra to look at a faraway galaxy first noticed by the James Webb Space Telescope. This galaxy emitted the sunshine captured by Webb 13.4 billion years in the past, when the universe was younger. Chandra’s X-ray information revealed a vibrant supermassive black hole on this galaxy and steered that supermassive black holes might type by the collapsing clouds in the early universe.
Sharp imaging has been essential for these discoveries. However Chandra is predicted to last only another 10 years. To maintain the seek for solutions going, astronomers might want to begin designing a “tremendous Chandra” X-ray observatory that would succeed Chandra in future many years, although NASA has not but introduced any agency plans to take action.
This text was printed first on The Conversation. It’s republished right here below a Inventive Commons license.
