The ejected cold gas of Abell 2597 falls back to the black hole.

Supermassive Black holes are the largest among all the types of black holes. They are present in the center of almost all the known massive galaxies. As far as our own galaxy is concerned, astronomers believe that it lies somewhere around the location of Sagittarius A*. The origin of supermassive black holes is still very much a mystery as the researchers have failed to figure out the procedure which leads to this massive celestial object. Several hypotheses circulate in the scientific community about the formation mechanisms of supermassive black holes but none of them have been proven to date.

One of the popular theories suggests that smaller black holes in the range of tens to hundreds of solar masses combine together by accretion to give birth to these much larger black holes. Another hypothesis revolves around the idea of a dense stellar cluster which experiences a core collapse as the negative heat capacity of the system drives the ‘Velocity Dispersion’ in the core. Similarly, another group of scientists believes that these supermassive black holes are produced from the Primordial black holes that were formed in the initial moments after the Big Bang due to the immense external pressure. Most of these ideas are limited to theory as the formation of black holes from the death of the first stars is the only hypothesis that has practical observations to back it up.

Recently, astronomers discovered a supermassive black hole in a far-off galaxy which is acting like a giant fountain. The researching team mentioned that the giant elliptical galaxy hosting this supermassive black hole is nearly a billion light-years away from our planet. The galaxy is being referred to as an ‘Enthusiastic Recycler’ following this latest finding. The supermassive black hole ejects cold molecular gas which falls back into it to complete the cycle. This concept was long theorized as ‘Fountain’ but lacked observational proof which was provided in this research. It is actually a galactic process of recycling star-forming material. Grant Tremblay, a Researcher at the Harvard Smithsonian Center for Astrophysics, described it by saying,

“This is possibly the first system in which we find clear evidence for both cold molecular gas inflow toward the black hole and outflow or uplift from the jets that the black hole launches. The supermassive black hole at the center of this giant galaxy acts like a mechanical pump in a fountain.”

Given the fact that black holes are generally linked with swallowing of matter, the idea of them throwing out any material seems a unique one. However, a recent study indicated that a supermassive black hole doesn’t swallow everything that comes its way as some of it funnels through the poles. The researchers mentioned that it could be due to the magnetic field lines similar to what happens with the solar wind when it approaches the magnetic field lines of Earth. In the case of solar wind, auroras are produced while things are different with black holes. They produce powerful streams of plasma which blasts out of their poles nearly at the speed of light and goes into space.

The supermassive black hole of the brightest cluster galaxy, Abell 2597, blasts cold molecular gas 30,000 light-years into space. Astronomers found that this cold gas rains back to the black hole’s accretion disk, which consists of a filamentary nebula having a mass of 3 billion suns and spread across an area of 100,000 light-years in the center of the galaxy. The team of Tremblay observed this effect for the first time in 2016 using the Atacama Large Millimeter/submillimeter Array (ALMA) and found Carbon Monoxide, at incredibly low temperatures (-260^o C to -250^o C), raining back towards the black hole. Prior to that, the Very Large Telescope of ESO allowed the scientists to see the jets ejected by the black hole.

Chandra X-ray Observatory of NASA was used for sake of follow-up observations and they confirmed that both the inflow and outflow belong to the same process. Tremblay elaborated that in 2016 in the following words:

“This very, very hot gas can quickly cool, condense, and precipitate in much the same way that warm, humid air in Earth’s atmosphere can spawn rain clouds and precipitation. The newly condensed clouds then rain in on the galaxy, fuelling star formation and feeding its supermassive black hole.”

Astronomers consider it a massive achievement as it will help them to better understand the formation of stars and the overall life cycle of galaxies.