For more than 150 years, the OJ 287 galaxy and its brightness variations five billion light years away has both puzzled and fascinated astronomers, because they suspect two supermassive black holes are merging in the core.
An international research team led by Dr. Efthalia Traianou of Heidelberg University recently succeeded in taking an image of the heart of the galaxy at a special level of detail. The groundbreaking image, taken with the aid of a space radio telescope, shows a heretofore unknown, heavily curved segment of the plasma jet spinning off the galaxy's center. The image provides new insights into the extreme conditions that prevail around supermassive black holes.
The research is published in the journal Astronomy & Astrophysics.
"We have never before observed a structure in the OJ 287 galaxy at the level of detail seen in the new image," emphasizes Dr. Traianou, a postdoctoral researcher in the team of Dr. Roman Gold at the Interdisciplinary Center for Scientific Computing of Heidelberg University.
The image, which penetrates deep into the galaxy's center, reveals the sharply curved, ribbon-like structure of the jet; it also points to new insights into the composition and the behavior of the plasma jet. Some regions exceed temperatures of ten trillion degrees Kelvin—evidence of extreme energy and movement being released in close proximity to a black hole.
The researchers also observed the formation, spread, and collision of a new shock wave along the jet and attribute it to an energy in the trillion-electron volt range from an unusual gamma ray measurement taken in 2017.
The image in the radio range was taken with a ground-space radio
interferometer consisting of a radio telescope in Earth's orbit—a
ten-meter-long antenna of the RadioAstron mission on board the Spektr-R
satellite—and a network of 27 ground observatories distributed across
Earth.
In this way, the researchers were able to create a virtual space
telescope with a diameter five times greater than the diameter of Earth;
its high resolution stems from the distance of the individual radio
observatories to one another. The image is based on a method of
measurement that takes advantage of the wave nature of light and the
associated overlapping waves.
The interferometric image underpins the assumption that a binary
supermassive black hole is located inside galaxy OJ 287. It also
provides important information on how the movements of such black holes
influence the form and orientation of the plasma jets emitted.
"Its special properties make the galaxy an ideal candidate for
further research into merging black holes and the associated
gravitational waves," states Efthalia Traianou.
Journal information: Astronomy & Astrophysics
.Provided by Heidelberg University
by Marietta Fuhrmann-Koch, Heidelberg University
edited by Gaby Clark, reviewed by Robert Egan
