Dr. Jane Lixin Dai, theoretical astrophysicist and assistant professor, and Prof. Enrico Ramirez-Ruiz, both from the DARK Cosmology Center at the Niels Bohr Institute of the University of Copenhagen, have recently provided a much-needed computer model to science. It is necessary for the study of tidal disturbance events – rare but extremely violent events taking place in the center of galaxies.
In the picture we see a cross-section of what happens when the material is swallowed up by the ruined star's black hole. An accretion disk is formed by the material (disk). There is too much material to get into the black hole right away. It heats up and emits large amounts of light and radiation, which are visible from the earth (double arrow). The computer model of Dr. med. Jane Dai takes into account the difference in the viewing angle from Earth, so we are now able to correctly categorize the variations in the observations. This means that we can study the properties of the black hole and learn about a celestial body that we would not otherwise be able to see.
At the center of every major galaxy is a supermassive black hole million to billion times heavier than the Sun. However, it is difficult to observe the majority of them because they do not emit light or radiation. This happens only when some form of material is dragged into the extremely strong gravitational field of the black hole. In rare cases, actually as rare as once in 1
When a tidal event occurs, the black hole is "overfed" with stellar debris for a while. "It's interesting to see how materials get into the black hole under such extreme conditions," says dr. Jane Dai, who led the study. "As the black hole freezes star gas, it emits a large amount of radiation, radiation is what we can observe, and we can understand the physics and calculate the properties of the black hole, which makes it extremely interesting to hunt
A Unification Model
Although the same physics are expected to occur in all tidal disturbances, the observed properties of these events have shown large variations: some emit mainly X-ray emissions, while others emit mainly visible light and UV , It was very much in demand to understand this diversity and put together these very different pieces of the puzzle. In the model, the viewer's perspective has made the difference. Astronomers observe everything from Earth, but the galaxies are randomly aligned across the universe. "It's like a veil that covers part of an animal, from some angles we see an exposed animal, but from other angles we see a covered animal, the animal is the same, but our perceptions are different," said Prof. Enrico Ramirez-Ruiz, co-author of the study
Jane Lixin Dai, theoretical astrophysicist at the DARK Cosmology Center and Niels Bohr International Academy at the Niels Bohr Institute of the University of Copenhagen, has long desired a computer model that manages
with the model Dr. Dai and her colleagues, who combine elements of general relativity, magnetic field, radiation and gas, now have a measure of what we expect when we see tidal events from different angles. This also allows us to put different events in a coherent framework. "We will see hundreds to thousands of tidal disturbance events in a few years, and this will give us many 'labs' to test our model and use it to learn more about black holes," Dr. Dai.
Cooperation and Perspectives
This work was made possible by the collaboration of Dr. med. Jane Dai of the DARK Cosmology Center at the Niels Bohr Institute (NBI), Prof. Enrico Ramirez-Ruiz of the NBI and the University of California, Santa Cruz (UCSC), and University of Maryland researchers: Prof. Jonathan McKinney, Ph.D. Nathaniel Roth and Prof. Cole Miller. In particular, state-of-the-art computer tools were used to solve the puzzle. These simulations were Dai and Dr. Roth performed on the recently acquired large computer cluster made possible by the Villum Grant by Professor Jens Hjorth, head of the DARK Cosmology Center, as well as NSF and NASA-funded clusters  This breakthrough has given the rapidly growing field of research a new perspective. "Only in the last decade have we been able to distinguish TDEs from other galactic phenomena, and Dr. Dai's model will provide us with the basic framework for understanding these rare events," says Prof. Enrico Ramirez-Ruiz.  In the coming years, DARK's and UCSC's transient survey of the Young Supernova Experiment (YSE) along with other telescopes, such as the Large Synoptic Survey Telescopes built in Chile, will give us access to much more data and be very helpful to expand this research area.