Scientists are challenged by a new image of the Black Hole’s powerful jets
The Event Horizon Telescope captured the most stunning images of a radiant star shooting from the closest active galaxy to our Milky Way.
When it was released in 2019 by the Event Horizon Telescope collaboration (EHT), the first ever image of a black-hole stunned people all over the globe. The unprecedented image was captured by a radio telescope array that spans across the globe. It revealed the eerie shadow surrounding a supermassive dark hole at Messier 87’s center. This black hole is 55 million light-years away.
The EHT team captured a stunning picture of Centaurus A, an AGN (active galactic nucleus) with a supermassive dark hole. Centaurus A is the closest AGN to our Milky Way. Scientists have studied it extensively, but not with the same level of resolution as the EHT.
According to a Nature Astronomy study, Monday’s images from the EHT collaboration capture jet structures at a scale of only 14 light hours. This is three times the distance between Earth, Pluto and Earth. It also covers an intergalactic expanse that spans more than 10,000,000 light years. The new images expose details that challenge existing models of jet formation.
“Centaurus A” is a well-known galaxy in the overall Astronomical Community, according to Michael Janssen, a Max Planck Institute for Radio Astronomy researcher who led the study. He said in an email.
He said that the best resolution observations of this source can resolve the jet on “only” light-year length scales. The EHT is a unique instrument that can provide a significant jump in resolution to all other observations. This allows us to see the jet up-close and personal on sub-light-day lengthscales right after it has been launched from the black hole.
The new EHT snapshot zooms in on one Centaurus A’s jets, instead of the famous Messier 87 image, which shows the outline of a supermassive dark hole. The gassy material created by accreting around the galaxy’s black hole is what creates the jet. This stream of ionized material is accelerated by the black holes intense tidal, magnetic and magnetic forces.
Janssen stated that the EHT had probed Centaurus A with a 16x sharper resolution than previous high-resolution studies. It also observed a 10x higher frequency. We suspected that the jet looked like a knotty, collimated structure as seen in previous [centimetre Very Long-Baseline Interferometry] observations. But we were also open to seeing something new and exciting with this unrivalled resolution.
Images of Centaurus A’s jet had not previously been able to show the variations in brightness. This property can provide clues about its fueling forces. Janssen stated that his team was stunned to see the EHT image after six hours of work on April 10, 2017. They also “performed many validation tests to confirm that what we are seeing is true.”
Janssen explained that “with the EHT we resolve sub-light day scales of the source and see the jet is actually strongly edges-brightened.” This is challenging our theoretical models which don’t produce the same effect in Centaurus A.
He said, “We believe that this suggests a very strong magnetic field that is being generated by a spinning central dark hole.” “Alternatively, the jet could be spinning very fast around its central axis, or it might only consist of a thin radiating sheath (like an extremely thin hollow cylinder).
The study not only revealed some unexpected problems to models but also supported a long-standing theory called “the fundamental plane black hole activity.” It predicts that this equation will hold true for all black holes regardless of their size.
This theory was successfully tested with black holes just a few hundred times larger than the Sun. It can also be used to test the theory on objects billions of times bigger than the Sun.
Janssen and his coworkers have now shown that this relationship can also be found in black holes millions of times larger than the Sun like the one at Centaurus A. These results suggest that supermassive black hole jets behave like scaled up versions of their stellar counterparts. This is consistent with Einstein’s theory about general relativity.
The new close-up view, along with its black hole environment can shed light on many other fascinating scientific questions. These jets are thought to be a significant source of ultrahigh-energy cosmic radiations. These are the most energetic particles reaching Earth and provide information about the high energy universe. Scientists are also interested in understanding how powerful jets from active nuclei affect the evolution of host galaxies.
Janssen and his coworkers plan to continue to study Centaurus A’s jet with an intercontinental telescope network, Global mm-VLBI Array, (GMVA VLBI), in order to uncover more of its secrets. This AGN’s proximity to the Milky Way and the mysterious properties of its jet might help answer some of the many questions regarding these radiant and pyrotechnic galacticae.
Janssen stated that Janssen will next image the jet using polarized light to determine the structure of the jet’s magnetic fields. This will give us more information about the nature and extent of edge-brightening, as well as help us to create a more restricted theoretical model of the jet.