- Researchers build a unified model that shows what it looks like when a black hole eats a star.
- This model shows different aspects of tidal disruption events based on observer’s viewing angle.
- It will help scientists better understand black holes and other celestial objects.
Our galaxy contains about 100 million black holes which are formed by the collision of massive stars at the end of their life cycle. There is a supermassive black hole at the center of the Milky Way galaxy, which is million to billion times heavier than our Sun.
Since black holes don’t eject any light, it’s hard to observe them directly. However, long ago, scientists predicted that black holes should have a finite entropy and they emit black body radiation due to quantum effects near event horizon.
When a star passes sufficiently close by the supermassive black hole (happens once in every 10,000 years), it gets ripped apart due to black hole’s intense gravitational force. This rare episode is known as a tidal disruption event, and when it occurs, the black hole is ‘overfed’ with stellar debris for a while.
Researchers at the University of Copenhagen have developed a unified model that describes what it looks like when a supermassive black hole eats a star. It gives a detailed view of black holes’ properties, and help us understand more about celestial bodies that we would otherwise not able to observe.
The research team used radiation emitting from black hole to understand its physics and properties. All tidal disruption events do not show the same phenomena – their properties vary to a great extent. Most events emit X-ray, while the other emits ultraviolet and visible lights.
This model shows different aspects of tidal disruption events based on observer’s viewing angle. All galaxies in the universe are randomly oriented. So whatever we observe into the distant space, we see an exposed view of a celestial body from some specific angles, whereas from other angles we see a covered view. So the thing we are observing is same; it’s our perception that’s making the difference.
The model takes various crucial factors into account, such as magnetic field, general relativity, radiation, angular momentum and mass of black holes, and more. It calculates what we expect to observe when looking at a tidal disruption event from multiple angles. This enabled researchers to put numerous events into a single coherent framework.
More specifically, they simulated a compact super-Eddington accretion disk around the supermassive black hole, suing a 3D general relativistic radiation magnetohydrodynamics code. Then the simulation data for radiative transfer analysis was post-processed using a Monte Carlo code.
Courtesy of researchers
The above image shows what happens to a star when it’s eaten by a supermassive black hole. The material of the star creates an accretion disk, through which a huge amount of star material could pass into the black hole instantly. The process heats up the material which leaves an incredible amount of radiation and light, detectable from our planet.
With the help of this new model, we can accurately differentiate the variations observed from Earth when viewing from different angles.
The future projects, including Young Supernova Experiment and Large Synoptic Survey Telescopes, will provide more data, which will further improve this model and expand the field of research.
Further studies are required to compare the contribution of optical emission from stream-stream collision and accretion. The team will examine the line profiles with higher resolution radiative transfer measurements. Moreover, they will be investigating simulations with different factors required to understand the complete evolution of a tidal disruption event.