An international collaboration was able to gain a hitherto unique view of what is happening in an active galaxy core. Using data collected from telescopes around the world, the team was able to detect a long-suspected process in the plasma jet of the galaxy’s active core, BL Lacertae. A media information from the Technical University of Dortmund.
Source: Technical University of Dortmund September 8, 2022.
September 8, 2022 – The evidence is so spectacular that the work has made it into the current issue of the renowned scientific journal Nature. Participating in the observations was also private lecturer Dr. Dominik Elsässer from the Faculty of Physics at the TU Dortmund. He worked with students from Würzburg to collect the data.
Active galactic nuclei are among the most luminous objects in the universe. These are extremely bright central regions of galaxies that can be observed from great distances. Their brightness mostly results from what is happening around a black hole, towards which matter from the surrounding area is falling. This sometimes creates plasma streams of charged particles, so-called jets. Astrophysicists research active galaxy nuclei and their jets because they suspect that these particles can accelerate enormously, reaching much higher energies than the largest particle accelerators on Earth.
Kink in the plasma flow causes fluctuations in brightness
A subclass of active galaxy cores are the so-called “blazars”. One well-known blazar is called BL Lacertae: regarding 900 million light-years away, this galaxy is home to a black hole with a mass 170 million times that of our sun. Analyzing data from a particular 2020 outburst of brightness from BL Lacertae, astronomers noticed that the brightness fluctuated with exceptional regularity. The researchers were able to explain these quasi-periodic oscillations with a change in the plasma of the jet, a so-called kink instability, which influences the magnetic field. The visible fluctuations in brightness occur because the high-energy particles in the jet move through exactly this kink.
“The kink instability is of great importance for the study of plasmas. The discovery in the jet of BL Lacertae now enables completely new insights into this cosmic particle accelerator,” says Dr. Dominik Elsasser. For this reason, the work was selected for publication by the renowned journal Nature. The publication was produced as part of the Whole Earth Blazar Telescope project, an international consortium of astronomers who specifically monitor blazars.
pupils*inside monitor the brightness of active galaxy nuclei Some of the data that led to the current Nature publication comes from a collaborative project between the Friedrich-Koenig-Gymnasium in Würzburg, the Chair of Astronomy at the University of Würzburg and the Faculty of Physics at the TU Dortmund. The brightness of active galaxy nuclei has been monitored in a school laboratory for ten years. The students lead*carry out the measurements independently on more than 100 nights per year and also evaluate the data independently. The scientific management of the project lies with Prof. Karl Mannheim from the University of Würzburg and Dr. Dominik Elsässer from the TU Dortmund.
Publication:
Rapid quasi-periodic oscillations in the relativistic jet of BL Lacertae, https://www.nature.com/articles/s41586-022-05038-9
