The most luminous galaxy known in the universe

Credit: ESO
Credit: ESO

Astronomers led by Tanio Díaz-Santos of the Universidad Diego Portales in Santiago, Chile, observed the most luminous quasar in the universe. The quasar lies at a distance that light needs 12.5 billion years to travel and is as luminous as 350 trillion Suns. Further study of the object revealed an extremely turbulent behaviour.


Initial observations of the galaxy W2246-0526, by the Wide-field Infrared Survey Explorer (WISE) showed that it hosts a deeply-buried Active Galactic Nucleus (AGN). AGN are galaxies that have very bright nuclei, so bright that the central region can be more luminous than the entire remaining galaxy light. Many AGN are strong emitters of X-rays, radio and Ultraviolet radiation, as well as optical radiation. Quasars are the most luminous AGN. The power of AGN is thought to originate by centrally located supermassive black holes (SMBHs).


Further observation using the Atacama Large Millimeter/submillimeter Array (ALMA) observatory showed that the interstellar material of the galaxy is in an extremely turbulent and dynamic state. A disk of gas is superheated as it spirals on the SMBH at the galaxy’s core. The light from the bright accretion disk is absorbed by a surrounding thick blanket of dust and re-emits the energy as infrared light, before it escapes. Scientists suspect that the galaxy is in a transformative stage of its life. Eventually the intense infrared radiation will boil away all of the galaxy’s interstellar gas and the galaxy will mature into a more traditional quasar.


Publication: Diaz-Santos et al. 2015

Source: ESO