When new stars are birthed into the vast void of the cosmos, the areas from whence they came are cold, dense clouds of light gases, such as hydrogen and helium. Though, these birthing clouds can be destroyed by a seemingly invisible predator lurking from within the shadows. When a black hole heats up to unimaginable temperatures, dispersing the cloud’s gas from its nebula, it forever alters the way in which the stars within a galaxy were to be formed.
The way in which this galactic destruction occurs is when a violent “wind” is produced near a galaxy’s supermassive black hole, normally in the center, that thrusts an outward torrent of cold gas thousands of light-years across. A joint observation venture was launched by teams from the Japanese Suzaku X-ray satellite and the European Space Agency’s (ESO) infrared Herschel Space Observatory to find the origins of these winds. They stated their discovery validates the long-suspected mechanism that enables a supermassive black hole to be an arbiter of evolution of its host galaxy.
Francesco Tombesi, a researcher from NASA’s Goddard Space Flight Center, stated the study is the first time scientists have been able to observe a galaxy’s active “feeding” black hole to properties at much more massive scales. “We detect the wind arising from the luminous disk of gas very close to the black hole,” he stated. This super-heated gas is responsible for ejecting gases from pre-formation star clouds in the central areas of galaxies. Tombesi and his team looked upon the galaxy known as IRAS F11119+3257 (F11119) to prove their hypothesis.
Many galaxies, including the Milky Way and F11119, are the hosts to supermassive black holes. A supermassive black hole is calculated to be an area of hitherto unknown gravitational forces – one estimated at over 16 million times the mass of the Sun. A black hole fuels its cosmic rage through a rotating disk of gases and other matter, called an accretion disk. Some accretion disks have been observed to be hundreds of times the size of the Solar System. Closer towards the black hole lies the event horizon. This is the point at which the gravitational pull is so forceful, even light cannot escape. As the orbiting cosmic material is pulled closer to the center, it reaches temperatures of tens and even hundreds of millions of degrees. A temperature at which subatomic particles become unstable, ripping apart and releasing X-ray and gamma radiation. Scientists state this is the reason for a galaxy’s massive energy output, which surpasses the Sun’s by over a trillion times. Though, this cannot be seen by normal space telescopes, for the galaxy is cloaked in star dust, therefore, most of the emissions are observed in the form of infrared light.
The novel findings solve the long-lasting puzzle of how black holes are able to shut the door on stellar creation. They found that galaxies show a positive correlation between the mass of a central black hole and the stellar properties that span thousands of light-years across, called a galactic bulge. Thus, galaxies with a larger black hole normally possess a galactic bulge with proportionately greater stellar masses and stars with a greater relative velocity.
Black holes grow by the same vice as their host galaxies, colliding with one another after their respective gravitational pulls unite them. Though, galactic mergers perturb galaxies, leading to an enhanced star formation that sends a surplus of gas and matter towards a black hole. In theory, this process should put an simple relationship between a black hole’s growth and the galaxy’s evolution into disarray. However, it does not, weirdly.
Sylvain Veilleux, a researcher at the University of Maryland and member of the team, explained, “These connections suggested the black hole was providing some form of feedback that modulated star formation in the wider galaxy, but it was difficult to see how.” He said since they discovered the strong, violent molecular floods of cold gas in galaxies with black holes, they began to unearth the connection. In 2013, Veilleux used the highly-advanced mechanisms at the ESO’s Herschel Space Observatory to view F11119 more closely. He found that there was a massive outflow of hydroxyl molecules (-OH) blasting through the galaxy at two million miles per hour, or about 18 percent the speed of light. In the current study, Veilleux and Tombesi, along with their respective teams, estimated this overflow of cold gas occurs in a location around 1,000 light-years from the center of F11119. This overflow is so large, it equates to over 800 times the mass of the Sun.
Back in 2013, the team at the Suzaku X-ray Imaging Spectrometer, viewing F11119, obtained clear imaging of the galaxy for three days. The wavelengths of light measured from the spectrometer revealed X-ray-absorbing gases are moving out from the black hole’s accretion disk at over 170 million miles per hour, or just about 25 percent the speed of light. Marcio Meléndez, another member of the team from the University of Maryland, stated the black hole is accreting gas and matter at such a fast rate, it heats the disk to such a temperature that it is able to convert matter into X-ray and gamma ray radiation that makes up 80 percent of the energy in F11119. Though, since the accretion disk has such a great luminosity, some of the gas that accelerates away from it creates the X-ray winds that rip apart infant stars.
Scientists currently believe that high energy, ultraluminous galaxies like F11119 represent the early stages of the formation of a quasar, one of the types of a black hole-derived galaxy with extreme levels of luminosity, spanning a great range of wavelengths. According to this assumption, the central black hole will inevitably consume the rest of the gas in the galaxy. Afterwards, the black hole will dissipate in an astronomical phenomenon called Hawking radiation, shutting the door on any new star formation that would have been birthed by the galaxy.
By Alex Lemieux
Photo by NASA, Dana Berry/Skyworks Digital – Flickr License
Photo by Phil Plait – Flickr License