An international team of astrophysicists from South Africa, Britain, France and the US have found great variability in the brightness of light seen around one of the closest black holes in our galaxy, 9,600 light-years from Earth, and they conclude it is caused by a huge distortion in its adsorption disk
This object, MAXI J1820 + 070, erupted as a new transient X-ray source in March 2018 and was discovered by a Japanese X-ray telescope located in the International Space Station. More compact can be a white dwarf, a neutron star or a black hole.In this case the MAXI J1820 + 070 includes a black hole whose mass is at least eight times greater than our solar mass.
The first findings are now published in the important international journal Monthly Notices of the Royal Astronomical Society, and the lead author is Dr. Jasimol Thomas, a postdoctoral fellow in the South African Astronomical Observatory.
The discovery presented in the article was revealed from an extensive and detailed light curve obtained for almost a year from dedicated amateurs from around the world who are part of AAVSO (American Association of Changing Stars). MAXI J1820 + 070 is one of the three brightest X-ray transmitters ever observed, a result of its proximity to Earth and being outside the hiding plain of our Milky Way galaxy. It stayed bright for many months, and it allowed so many amateurs to follow it.
Professor Phil Charles, a researcher at the University of Southampton and a member of the research team, explained: “Material from the normal planet is attracted by the compact bone into the adsorbent disk of a spinning gas. Large eruptions occur when the material in the disk becomes hot and unstable. “Abundance of energy before it crosses the horizon of events. This process is chaotic and very changing, and the time periods range from milliseconds to months.”
The research team created the bra of the system, which shows how a huge output of X-ray radiation emanates very close to the black hole, then radiates on the surrounding material, especially on the adsorption disk, and heats it to a temperature of up to around 10,000K, which seems to emit light. This is why when the X-ray burst is small, so is the optical light.
But something unexpected happened almost three months after the eruption began when the optical light curve began a huge modulation – a bit like rotating a dimmer switch up and down and almost doubling its brightness at peak – in a period of about 17 hours. But there was no change in the X-ray radiation output, which remained constant. Modules that appear small and semi-periodic have been seen in the past in eruptions of other X-ray transmitters, but nothing of this magnitude has ever been seen before.