It sounds like an even more twisted version of Wonderland, but magnifying glasses are everywhere in the sky. They just don’t look like what you would expect them to look like.
Sometimes, the gravity of a planet or galaxy or any other object in space bends the path of light to another object and therefore amplifies it. Gravitational lensing has now given researchers an unprecedented closeup (as close as you can get to something 12 billion light years away) of at least one supermassive black hole that formed when the universe was only yawning awake.
Observations of the system MG B2016+112 see it as it was at the dawn of the universe. Astrophysicist Dan Schwartz of the Center for Astrophysics, Harvard & Smithsonian (CfA), and his team detected two objects in this system—either a duo of growing supermassive black holes which are spewing out X-rays or a growing black hole and its gargantuan X-ray jet. At least they were still growing billions of years ago, since it took that long for their light to reach Earth. Schwartz recently led a study published in The Astrophysical Journal.
“Two of the images we detected were more than 15 times brighter than they should be if they came from the same source as the blended image,” he told SYFY WIRE. “The probability of an unrelated source being so close in the sky is minuscule, so we deduced that there are two X-ray emitters that are both part of the same physical system."
Gravitational lensing often produces multiple images. CHANDRA radio telescope data originally showed three, possibly four, images that were too close to each other to make out (and otherwise too faint to see), even with a hi-res model of the galaxy lensing those objects. These were separated by only 650 light years. Most CHANDRA measurements of black holes have involved objects that were either further apart or closer to our planet. There has been an X-ray jet found further out before, but it was 160,000 light years away from the nearest black hole.
Finding such ancient objects could reveal more about how binary black holes formed in the nascent universe, or, if what CHANDRA was looking at is really a black hole and an immense jet, the origin of phenomena like X-ray and radio jets. Some think enormous early stars played fast and hard back then. The recklessly burn through their hydrogen until there was none left, collapsing into themselves and forming supermassive black holes. Observations like this can shed more light on how the beasts now known as supermassive black holes actually formed.
But first, scientists need to figure out what the objects actually are before looking further into their origins.
“If they are a binary black hole pair, then that is evidence black holes can grow by mergers of smaller black holes,” said Schwartz. “A prominent competing mechanism is that the black holes just accrete matter at much faster than the so-called Eddington limit. Both mechanisms could be operating simultaneously.”
The (theoretical) upper limit to the mass that of a star or a black hole’s accretion disc is known as the Eddington limit. When an object reaches this limit, radiation is thought to be balanced with inward gravitational force, which would make a star collapse if it went over the edge. Too much luminosity would send a star into the throes of self-destruction by obliterating its outer layers. A black hole’s luminosity needs to be proportional to how fast it gains mass. If that goes overkill, then more outward pressure than inward gravity would make it unable to accrete.
Future telescopes that pick up on gravitational lensing could tell Schwartz and other scientists more about black hole physics that are still in the dark. The Vera Rubin, SKA, Nancy Grace Roman and other upcoming telescopes will probably have a high enough resolution to see objects such as whatever is lurking in MG B2016+112 like never before.
“We are looking for offsets among the radio, optical, and X-ray emission in active galaxies,” he said. “We also hope to address questions of how black holes form jets, the cycles of activity of powerful supermassive black holes, and how those cycles are involved in the feedback which causes black hole mass and galaxy bulge mass to be correlated.”
Maybe humans didn’t invent gravitational lensing, but the way things are observed through it could change many things we thought we knew about the universe.