Astronomers work on new method to detect black holes

Astronomers are working towards developing a new method for detecting supermassive black holes in the centers of galaxies - looking at the chemical composition in the galaxy's core.  Using the Atacama Large Millimeter Array (ALMA), a powerful telescope in Chile that detects radio waves, astronomers looked at the center of NGC 1097, a spiral galaxy known to contain an active supermassive black hole.  They found large amounts of a chemical called hydrogen cyanide in the region surrounding the black hole; this is a result of the black hole heating the material around it.  

Looking at the chemical composition at the centers of other galaxies could help us find black holes we haven't been able to see before; if galaxies have lots of dust at their center, it can be hard for us to see the signatures of a black hole in the light that comes from there since much of the light will be absorbed by dust.  However, radio waves do not get absorbed the way most other light does, making them useful for observing galaxies that have lots of dust in them.  If we can use radio observations to search for these chemical signatures in other galaxies, we may find lots of new black holes.  

The image on the left shows NGC 1097 in visible light.  The image on the right is taken by radio telescope ALMA, and shows the center of NGC 1097.  The plus sign marks the location of the supermassive black hole.  (Image credit: ESO, ALMA)

The image on the left shows NGC 1097 in visible light.  The image on the right is taken by radio telescope ALMA, and shows the center of NGC 1097.  The plus sign marks the location of the supermassive black hole.  (Image credit: ESO, ALMA)