An article published in “The Astrophysical Journal” describes the observation of two events consisting of a supermassive black hole that swallowed large amounts of gas and then emits a part of them in the form of very high-energy jets. A team of astronomers led by Julie Comerford of the University of Colorado at Boulder used observations made with various telescopes to capture this repeated activity at the center of a galaxy known as SDSS J1354+1327 or simply J1354.
Galaxies normally have a supermassive black hole at their center that can have a mass millions or even billions of times the Sun’s. The activity around them depends on the amount of gas and dust captured by their very powerful gravity. Under certain conditions, huge amounts of materials can be swallowed by one of these black holes, sometimes enough to cause an indigestion.
In the case of the supermassive black hole of the galaxy J1354, about 800 million light years away from Earth, the astronomers have found traces of two such events and as many explosions of energy occurred when a part of the gas was emitted in the form of extremely energy-charged jets. To find those traces they put together observations of the Hubble Space Telescope, the Chandra X-ray Observatory, the W.M. Keck Observatory in Hawaii and the Apache Point Observatory in New Mexico.
Chandra detected an X-ray emission from the galaxy J1354 that indicates the presence of a supermassive black hole surrounded by gas because the gas that comes close to it is heated so much that it emit that type of electromagnetic radiation. Part of that gas is going to be swallowed while another part will be ejected in a powerful explosion. Comparing X-ray images to visible light images captured by Hubble, the astronomers could confirm that it’s in the center of the galaxy J1354.
Other observations made with the W.M. Keck and Apache Point telescopes, combined with those of Hubble, showed the effects of the ionization of the atoms ejected at the south of the galaxy up to a distance of 30,000 light years from it. The most likely cause is a strong emission of radiation from the vicinity of the supermassive black hole, an indication that the meal has begun.
At the north of the galaxy, traces of a shock wave were found about 3,000 light years from the black hole suggesting that there was an explosion after another mass of gas was consumed about 100,000 years later. These are strong clues that those black holes have short moments in astronomical terms in which they’re very active and other periods of greater tranquility.
According to the astronomers, the double meal is linked to the presence of a second galaxy close to J1354. The two galaxies are connected by stars and gases, traces of an ancient collision between the two of them. Masses of gas and dust coming from the neighbor ended up in the supermassive black hole at the center of J1354.
The image shows the galaxy SDSS J1354+1327 at the lower center and its companion SDSS J1354+1328 above it. The inset shows an image of SDSS J1354+1327 which combines Hubble’s red, green and blue colors with the Chandra observations shown in purple. The bubble on the north side shows the hot ionized gas in the area around the supermassive black hole.
These events that cause explosions of energy generate what’s called in jargon the active galactic core, when the supermassive black hole warms gas around it so much that it make them very bright. The enormous energies released in these events make them very visible and particularly interesting to study.