A less lucky star was dismembered by five horses under the powerful gravity of the black hole, resulting in the outbreak of relativistic jet .
Image source: Carl Knox – OzGrav, ARC Centre of Excellence for Gravitational Wave Discovery, Swinburne University of Technology
Some stars just have bad luck. A typical galaxy has a number of stars in the order of billions, however, every 100,000 years or so, a star will be torn apart because it is too close to the supermassive black hole (supermassive black hole) hidden in the center of the galaxy. These cosmic giants have millions to billions of times the mass of sun , and their huge gravity can destroy an unlucky star.
star fragments will circle and fall into black holes, which feed on these wreckages. However, the scene will be very chaotic when the black hole is feasting on. In a small part, this star destruction can provide energy to a jet of high-energy matter that travels outward at a speed of nearly light, and if the jet of matter is directed to us, its brightness will increase, just as the whistle sounds seemingly louder as the car drives towards us.
Modern astronomy surveys find such a stellar ramen effect (spaghettification), also known as tidal disruption event (TDE), about once or twice a month. However, so far we have only observed three of them that can emit strong jets, the most recent in 2011.
Earlier this year, we were lucky enough to discover another such event that happened half of the universe. The relevant research was published in the journal "Nature Astronomy" on November 30. An international research team used the world's best telescope to observe it for more than three months, gaining the best perspective on the birth and development of black hole jets so far.
black holes and jets
swallowed stars is an important way for black holes to grow, especially in the early universe. This supermassive black hole, which is now at the center of a galaxy, must have grown very rapidly when it was young to reach its current size. These devastating events also provide a unique window for observing the fastest-eating black holes. We can never reproduce similar high energy and strong gravity in the lab, so these rare events help us understand the most extreme cases of astrophysics . More importantly, these events allow us to test how the jet is formed. Jets are natural by-products of gas flowing into central celestial bodies, which transport energy from central objects to their surroundings.
The strongest jets known so far come from supermassive black holes in the center of the galaxy. The matter and energy in these jets can trigger or stop the formation of stars and affect the evolution of the entire galaxy.
supermassive black holes usually change very slowly, but tidal disintegration events become an exception to the norm, because in this case a large amount of gas is "poured" very close to the black hole.
After this, the black hole will quickly swallow this matter, and the behavior of the black hole will also change within a few days or months. Using state-of-the-art telescopes for special observation activities can provide us with a large amount of data about these singular phenomena, and these data can be used to test scientists' theories on the formation and evolution of jets.
A flash
In February 2022, an optical sky survey mission discovered a bright flash from the center of a distant galaxy. This flash has been spreading to us for more than 8.5 billion years, longer than half of the cosmic lifespan. Telescopes around the world have taken action to learn more about this event. Astronomers named this tidal collapse event AT2022cmc.
bright radiation generated by the tidal disintegration event covers the entire electromagnetic spectrum , from radio to visible light to X-ray . X-ray emission comes from near the black hole, while other wavelengths emit from further downstream of the jet.
Image source: Zwicky Transient Facility / R. Hurt (Caltech/IPAC)
Image Chinese: Wazha
This event has extraordinary brightness, especially in the range of X-ray wavelengths. The energy released by the X-ray here in 1 second is higher than that of the sun in 10 million years, and the change speed is also extremely fast. The change in brightness can even occur within 15 minutes. It is worth noting that there is also strong emissions in the radio and millimeter wavelength ranges, and the brightness will become higher over time.
These characteristics indicate that AT2022cmc is a new tidal collapse event, the farthest distance discovered so far and the first time it has observed strong jets of matter in 11 years.
X rays and radio waves
100 days after the discovery of this tidal collapse event, a team led by Dheeraj Pasham of the Massachusetts Institute of Technology (MIThings 4) observed the event using a series of telescopes, and the data obtained covers radio, visible light, ultraviolet and X-ray emissions generated by different parts of inflow and outflow gases. Detailed models from the
research team show that most of the radiation comes from strong jets emitted by the black hole that "feeds" quickly. The unfortunately dead star is likely to be a low-mass dwarf star. At the peak of the black hole's "feeds", it swallows gas at a speed that is enough to make the entire sun disappear in just a few years.
researchers found that the jet is moving at 99.993% of the speed of light, and most of the energy is carried by particles (ions) in the jet, not by magnetic fields, which is unexpected to the researchers, because most current theories predict that the magnetic field is crucial in the process of jet formation and should carry most of the energy.
updated telescopes, better field of view
More updated telescopes have allowed scientists to establish and more complex theoretical models than they were a decade ago. New research has thus provided the most detailed reports on the birth and evolution of relativistic jets to date, challenging existing theoretical expectations, and improving our understanding of astrophysics in the most extreme situations.
In the next few years, new facilities including the Vera Rubin Observatory of Chile should discover more such events, deeper into the farther universe; powerful new radio telescopes, such as the square kilometer array radio telescope (SKA), will allow for more detailed tracking and characterization of such jets.
New research shows the exciting science generated from these telescopes, opening a new window for some of the most active events in the universe.
Reference source:
[1]https://theconversation.com/astronomers-witness-the-dying-flare-of-a-star-torn-apart-by-a-black-hole-halfway-cross-the-universe-195453
[2] Pasham, D.R., Lucchini, M., Laskar, T. et al.The Birth of a Relativistic Jet Following the Disruption of a Star by a Cosmological Black Hole.Nat Astron(2022). https://doi.org/10.1038/s41550-022-01820-x
