A black gap ejected a flame away from us, however its intense gravity directed the explosion again in our route
In 1916 Albert Einstein completed his general theory of relativity, a journey that began in 1905 with his attempts to reconcile Newton’s own theories of gravity with the laws of electromagnetism. Once completed, Einstein’s theory provided a unified description of gravity as a geometric property of the cosmos in which massive objects change the curvature of space-time and affect everything around them.
In addition, Einstein’s field equations predicted the existence of black holes, objects so massive that even light cannot escape their surface. GR also predicts that black holes will bend light near them, an effect that can be used by astronomers to observe objects further away. Using this technique, an international team of scientists has achieved an unprecedented feat by observing light caused by an X-ray beam that took place behind a black hole.
The team was led by Dr. Dan Wilkins, an astrophysicist at the Kavli Institute for Particle Astrophysics and Cosmology at Stanford University and a NASA Einstein Fellow. He was assisted by researchers from Saint Mary’s University in Halifax, Nova Scotia; the Institute for Gravitation and the Cosmos at Pennsylvania State University and the SRON Netherlands Institute for Space Research.
Diagram showing how the extreme gravity of a black hole makes x-ray echoes visible from its other side. Photo credit: ESA
Using ESA’s XMM Newtonian and NASA’s NuSTAR space telescope, Wilkins and his team observed bright X-rays emanating from a supermassive black hole (SMBH) in the center of I Zwicky 1 – a spiral galaxy 1,800 light years away from Earth. The astronomers did not expect this, but because of the extreme gravity of the SMBH (which comes from 10 million solar masses), flares from behind were made visible to the XMM-Newton and NuSTAR.
The discovery was made as part of a survey aimed at learning more about the bright and mysterious X-ray light that surrounds the event horizon of a black hole. This “corona” (as its nickname) is believed to be the result of gas continuously falling into the black hole, forming a rotating disc around it. When the ring is accelerated to near the speed of light, it is heated to millions of degrees, creating magnetic fields that twist into knots.
Eventually these fields twist to the point where they break and release all of the energy they have stored in them. This energy is then transferred to matter in the surrounding disk, which creates the “corona” of high-energy X-ray electrons. The X-ray flares were initially visible to Wilkins and his team as light echoes that were reflected by incident gas particles that were accreted on the surface of the black hole.
In this case, the observed X-ray beam was so bright that some of the X-rays fell on the gas disk falling into the black hole. As the flares subsided, the telescopes picked up weaker flashes, which were echoes of the flares reflected from the gas behind the black hole. The light from these flashes was deflected by the strong gravity of the black hole and became visible to the telescopes, albeit with a slight delay.
ESA’s XMM Newton Observatory was set up in 1999 to study interstellar X-ray sources. Photo credit: ESA
The team was able to identify where the X-ray flashes came from based on the specific “colors” of the light they emitted (their specific wavelength). The colors of the X-rays coming from the other side of the black hole were slightly altered by the extreme gravitational environment. In addition, X-ray echoes are seen at different times depending on where they were reflected from on the disk; they contain a lot of information about what is happening around a black hole.
As a result, these observations not only confirmed the behavior predicted by general relativity, but also enabled the team, for the first time, to study processes behind a black hole. In the near future, Wilkins and his team plan to use this technique to create a 3D map of the black hole’s surroundings and investigate other secrets of the black hole. For example, Wilkins and his colleagues want to solve the mystery of how the corona produced such bright X-rays.
These missions will continue to rely on the XMM Newtonian Space Telescope as well as the next generation X-ray observatory proposed by ESA known as the Advanced Telescope for High-Energy Astrophysics (ATHENA). These and other space telescopes slated to launch in the coming years promise to reveal much more about the parts of the universe we cannot see and shed more light on its many mysteries.
Further reading: ESA, Natur
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