At the center of our galaxy, the Milky Way sits a supermassive black hole where the sun, the solar system, and along with everything else in the galaxy revolves. A dance that begun long before humans came into existence, and scientists are doing their best in understanding how black holes work, why they exist, and what knowledge do they hold in the formation of the universe.
Recently, astronomers explained in their new research paper that the black hole is blinking at us. BGR reported that the phenomenon might be caused by a disk of material surrounding it that may be producing a flickering signal due to "hot spots" that form within it.
The Blink: A Puzzling Phenomenon
Using the data from the Atacama Large Millimeter/Submillimeter Array (ALMA) telescope operated by the European Southern Observatory in Chile, the astronomers have documented a puzzling phenomenon currently happening near the location of Sagittarius A. Where the black hole is believed to be situated at the heart of the Milky Way galaxy.
The data seems to imply that the black hole is blinking in the Earth's direction. The astronomers published their work in The Astrophysical Journal Letters, wherein they described their findings of the rapidly-flickering light curves from the black hole. However, black holes are known to not glow or emit light, so the scientists are baffled by their observations.
Yuhei Iwata, the lead author of the paper, said that Sgr A* is known to sometimes flicker up in a millimeter wavelength, but this time ALMA obtained a high-quality data of radio wave intensity variation of Sgr A* for 70 minutes per day within ten days. They found two trends of variations, which are the quasi-periodic variations with a typical time scale of 30 minutes and hour-long slow variations.
Why is it Blinking Towards Earth?
Scientists only have limited knowledge about the black holes in the universe, mainly because they are invisible to the visible light making it harder to study them. But their intense gravitational pull tends to attract materials that they are slurping up.
These include hot gases, dust, and debris that form into a halo around the black hole known as an accretion disk. The matter inside the accretion disk can move at speeds that approach the speed of light.
Scientists believe that the flickering emissions originate within the accretion disk closest to the black hole itself. Within the fast-moving disk, hot spots can form that emits light, which seems to appear to "blink" at the Earth's direction when they are moving towards the Earth in their orbit of the black hole.
In a press release, scientists explained that "hot spots are sporadically formed in the disk and circle around the black hole, emitting strong millimeter waves." Moreover, Einstein's special relativity theory said that emission is largely amplified when moving toward the observer with speed similar to light.
