NASA's Chandra X-ray Observatory has detected the largest x-ray flare which reportedly exploded from a supermassive black hole located at the heart of the Milky Way galaxy.

According to Daily Mail, the supermassive black hole called Sagittarius A*, or Sgr A*, which the megaflare originated from, is estimated to hold 4.5 million times the mass of our sun. The flare was three times brighter than the previous brightest X-ray flare back in 2012.

As to what caused the flare, Daily Mail reports that astronomers have explained two possibilities: First, "an asteroid came too close to the supermassive black hole and was torn apart by gravity;" second, "the magnetic field lines within the gas flowing towards Sgr A* could be tightly packed and become tangled."

The flare was discovered unexpectedly while astronomers were observing Sgr A*'s reaction to a cloud of gas known as G2 which is in close proximity during the spring of 2014, the news outlet notes. The astronomers were expecting some kind of reaction from the G2 gas cloud, but ended up getting a different surprise instead.

"Unfortunately, the G2 gas cloud didn't produce the fireworks we were hoping for when it got close to Sgr A*," according to lead researcher Daryl Haggard of Amherst College in Massachusetts, as quoted by Daily Mail. "However, nature often surprises us and we saw something else that was really exciting."

The first theory suggests that the tidal disruption from the G2 and the Sgr A* results to a scattering of debris, which would then become very hot and produce X-rays before getting sucked into the black hole and disappearing forever, the news outlet adds.

"If an asteroid was torn apart, it would go around the black hole for a couple of hours - like water circling an open drain - before falling in," explained Fred Baganoff, the co-author of the Massachusetts Institute of Technology in Cambridge, Massachusetts. "That's just how long we saw the brightest X-ray flare last, so that is an intriguing clue for us to consider," he added, as quoted by the Daily Mail.

The second theory, on the other hand, states that what astronomers are seeing are "the tangled, mangled lines of many magnetic fields as they were sucked in towards the black hole's center," according to io9. These magnetic lines could produce bright outbursts of X-rays, which, Daily Mail says, has the same patterns of intensity that was also seen on our solar system's sun.

Gabriele Ponti of the Max Planck Institute for Astrophysics in Garching, Germany, said that the only explanation that can be derived from this is there's still no final explanation regarding the large Sgr A* flare, Daily Mail adds.

"Such rare and extreme events give us a unique chance to use a mere trickle of infalling matter to understand the physics of one of the most bizarre objects in our galaxy," Ponti said, as reported by the news outlet.