Washington: A new method is set to focus on the difference of emission frequencies from molecules uniquely found around black holes, which may open the way for "the search for a hidden black hole" which is overcast with dust particles and optically invisible.
An international research team led by Takuma Izumi, a second-year master`s student of science at the University of Tokyo, and Kotaro Kohno, a professor at the University of Tokyo, successfully captured a detailed image of high-density molecular gas around an active supermassive black hole at the center of a galaxy called NGC 1097 at the highest sensitivity ever achieved.
The observation result shows that there is a unique chemical composition characterized by enhancement of hydrogen cyanide (HCN) around the black hole, which would be caused by high temperature heating of the environment surrounding the black hole.
With recent advancement in observational research, it has been revealed that many of galaxies contain a supermassive black hole at their centers.
However, the formation process of such massive black holes is yet to be discovered by modern astronomy.
A study result shows that the mass of a supermassive black hole is approximately proportional to that of the central part of the galaxy (galactic bulge).
This means that the higher mass galaxy has a higher mass black hole.
A galactic bulge is thought to evolve through numerous mergers and collisions with other galaxies which would bring a large amount of interstellar materials into a galactic center and further the evolution of a black hole.
To investigate this "coevolution" of a galaxy and a black hole, it is necessary to study the mass of black holes in all ages as well as the kinematics of surrounding interstellar molecules that flow into the black hole.
However, the first thing we need to do is to confirm the existence of a black hole at the galactic center by observation.
A number of similar black hole exploration methods have also been proposed in optical/infrared spectra so far, but one crucial problem is that emissions at these wavelengths are absorbed by interstellar dust particles although the more active black holes contain more dust particles.
This means conventional exploration methods have difficulty in finding a black hole during the most active stage of its evolution process.
The goal of the research group is to establish a new exploration method using as reference various molecular/atomic emission lines which can be observed at millimeter/submillimeter wavelengths.