Black hole discovered outside Milky Way
Quasars play fundamental role in history of the universe, Tel Aviv University researcher says
A group of astronomers working in collaboration with researchers at Tel Aviv University have discovered clouds of gas revolving around a black hole that make up the center of the 3C 273 quasar, relying upon earlier measurements made at the Florence and George Wise Observatory in 2000.
Prof. Hagai Netzer of Tel Aviv University’s School of Physics and Astronomy worked with a team of international astronomers who uncovered gas clouds rotating around a black hole, shaping the center of a highly luminous astronomical object known as a quasar.
This marks the first detection of an enormous black hole outside the Milky Way galaxy.
The first quasar, 3C 273 was discovered in 1963 by astronomer Maarten Schmidt, and known to be much brighter than all of the stars in the Milky Way together.
It is believed that large galaxies have a massive black hole in the center that may weigh up to a billion times that of the sun. Gases which flow into the black hole cause energy to be emitted as electromagnetic radiation.
This radiation is so powerful, it makes these objects highly luminous, and they shine much brighter than ordinary galaxies.
In a paper published in Nature on Thursday, Prof. Netzer along with the group of astronomers, GRAVITY (a second generation instrument on the Very Large Telescope Interferometer) revealed that these swiftly moving clouds around the enormous black hole make up the center of the quasar.
In 2000, the earliest measurements of the black hole’s mass inside quasar 3C 273 were made by Dr. Shai Kaspi and Prof. Netzer.
This marked the first discovery of clouds of gas rotating around a black hole, allowing researchers to use this data as a scale by which to analyze the masses of black holes in future quasars.
The GRAVITY instrument used to measure these large galactic objects is composed of four telescopes that are set at different locations and able to provide images which are projected virtually.
Thus vast remote astronomical objects are able to be viewed at an exceptionally high resolution.
According to the California Institute of Technology’s website, this telescope – known as an interferometer – works by joining multiple sources of light to produce an interference pattern, which can then be examined to generate a multi-dimensional image.
The interferometer used in this study was 130 meters long and located in Paranal, Chile.
Prof. Netzer added that “quasars are among the most distant astronomical objects that can be observed. They also play a fundamental role in the history of the universe, as their evolution is intricately tied to galaxy growth.
“While almost all large galaxies harbor a massive black hole at their centers, so far only one in our Milky Way has been accessible for such detailed studies.”
Dr. Eckhard Sturm of the Max Planck Institute for Extraterrestrial Physics (MPE) in Munich, Germany who co-led the study said: “Our observations can follow the motion of the gas and reveal that the clouds do whirl around the central black hole.”
He added that these discoveries were previously impossible since the inner section of the quasar is both small and distant – it is around 2.5 billion light years away.
Netzer added that “with the GRAVITY instrument, we can distinguish structures at the level of 10 micro-arc seconds, which corresponds to observing, for example, a 1-Euro [sized] coin on the moon.”
Dr. Jason Dexter, another scientist of MPE who took part in the research said: “Information about the motion and distance of the gas immediately around the black hole is crucial to measuring the mass of the black hole.”
Reinhard Genzel, head of the infrared research group at MPE added: “This is the first time that we can study the immediate environs of a massive black hole outside our home galaxy, the Milky Way. Black holes are intriguing objects, allowing us to probe physics under extreme conditions – and with GRAVITY we can now probe them both near and far.”