NASA scientists have revealed that they may have discovered the youngest black hole in the Milky Way galaxy, which formed just 1,000 years ago and is relatively close to Earth at just 26,000-light-years away.
NASA's Chandra X-Ray Observatory collected data that indicated a black hole may have formed very recently about 26,000-light-years away. Laura Lopez, NASA's Einstein fellow and Pappalardo Fellow in Physics at the Massachusetts Institute of Technology, said:
"It appears its parent star ended its life in a way that most others don’t."
Scientists observed a supernova remnant in our Galaxy known as W49B, which some had previously argued may have been formed by a gamma-ray burst (GRB). GRBs are extreme supernova explosions that are thought to be the most energetic and luminous events in the Universe, and mark the end of the lives of some very large stars (more than 25 times the mass of the Sun) after they've exhausted their nuclear fuel. When the star's nuclear fuel is exhausted, the energy of reactions that support the star in the core is depleted and collapses to form a black hole and the outer layers are thrown into space in a violent explosion known as a supernova explosion.
Typically, when a supernova explosion forms a black hole, the core material is pulled in completely. However, if it rotates rapidly as it collapses, some of the heavier metals in the core may be expelled in jets at the poles of the star at velocities near the speed of light. If the jets are expelled in the direction of the Earth, the energy is then beamed in a powerful flash of light known as a gamma-ray burst.
Keeping in mind the theory that W49B was formed by a gamma-ray burst, the scientists then wondered what a gamma-ray burst would look like after one-thousand years, and what it would leave behind. The researchers determined that the remnant of a gamma-ray burst would look unlike an ordinary supernova 1,000-years later.
A supernova is usually relatively spherical, however a supernova involving a gamma-ray burst could be expected to have heavy metal jets, that after 1,000 years would have expanded to form a bar with a large concentration of iron. Regular supernova formed from core-collapse don't have as much iron as those that are formed from gamma-ray bursts, so scientists can determine that a supernova formed from a gamma-ray burst by measuring the amounts of heavy metals compared with other elements in the supernova.
Researchers mapped and compared the amount of metals that were produced in the W49B supernova explosion, and found that W49B has low amounts of silicon and sulfer, much less than predicted for a normal core-collapse supernova. The Chandra Observatory also captured images of the "bar" of iron.
The scientists concluded from the Chandra X-Ray Observatory data that the shape and metals of W49B show the explosion has jets that theory predicts for gamma-ray bursts.
The researchers also used Chandra to look for the compact leftover from the supernova. In normal core-collapses, neutron stars often form from the leftover of a supernova explosion with a radius of just 10km. They looked for evidence of a neutron star, and were unable to fid one. The lack of evidence thus points the the existence of a black hole.
"In fact, the deep observation allowed us to say there's no neutron star in W49B that's even 1/100 as bright as astronomers think it would be. This result supports the fact that W49B’s supernova formed a black hole, which is consistent with the explosion having been a gamma-ray burst."
And the study concluded:
"This result means that these exotic explosions can happen within our own Galaxy, and further study of W49B will give great insights into how these awesome events come about."
Findings from the study will be published in an upcoming issue of the Astrophysical Journal.