Artist's impression of the galaxy W2246-0526
The most luminous galaxy known in the Universe — the quasar W2246-0526, seen when the Universe was less than 10% of its current age — is so turbulent that it is in the process of ejecting its entire supply of star-forming gas, according to new observations with the Atacama Large Millimeter/submillimeter Array (ALMA).
Quasars are distant galaxies with very active supermassive black holes at their centres that spew out powerful jets of particles and radiation. Most quasars shine brightly, but a tiny fraction [1]
of these energetic objects are of an unusual type known as Hot DOGs, or
Hot, Dust-Obscured Galaxies, including the galaxy WISE
J224607.57-052635.0 [2], the most luminous known galaxy in the Universe.
For the first time, a team of researchers led by Tanio Díaz-Santos of
the Universidad Diego Portales in Santiago, Chile, has used the unique
capabilities of ALMA [3] to peer inside W2246-0526 and trace the motion of ionised carbon atoms between the galaxy’s stars.
“Large amounts of this interstellar material were found in an
extremely turbulent and dynamic state, careening throughout the galaxy
at around two million kilometres per hour,” explains lead author Tanio Díaz-Santos.
The astronomers believe that this turbulent behaviour could be linked
to the galaxy’s extreme luminosity. W2246-0526 blasts out as much light
as roughly 350 trillion Suns. This startling brightness is powered by a
disc of gas that is superheated as it spirals in on the supermassive
black hole at the galaxy’s core. The light from the blazingly bright accretion disc
in the centre of this Hot DOG does not escape directly, it is absorbed
by a surrounding thick blanket of dust, which re-emits the energy as
infrared light [4].
This powerful infrared radiation has a direct and violent impact on
the entire galaxy. The region around the black hole is at least 100
times more luminous than the rest of the galaxy combined, thus releasing
intense yet localised radiation in W2246-0526 that is exerting
tremendous pressure on the entire galaxy [5].
“We suspected that this galaxy was in a transformative stage of its life because of the enormous amount of infrared energy,” said co-author Peter Eisenhardt, Project Scientist for WISE at NASA's Jet Propulsion Laboratory in Pasadena, California.
“ALMA has now shown us that the raging furnace in this galaxy is making the pot boil over,” adds Roberto Assef, also from Universidad Diego Portales and leader of the ALMA observations.
If these turbulent conditions continue, the intense infrared
radiation would boil away all of the galaxy’s interstellar gas. Models
of galaxy evolution based on the new ALMA data indicate that the
interstellar gas is already being ejected from the galaxy in all
directions.
“If this pattern continues, it is possible that W2246 will eventually mature into a more traditional quasar,” concludes Manuel Aravena, also from the Universidad Diego Portales. “Only
ALMA, with its unparalleled resolution, can allow us to see this object
in high definition and fathom such an important episode in the life of
this galaxy.”
Notes
[1] Only one of every 3000 quasars observed are classified as Hot DOGs.
[2] The full name of this remarkable object is WISE J224607.57-052635.0, it was found by NASA’s Wide-field Infrared Survey Explorer (WISE) spacecraft and the rest of the name gives the precise location of the quasar on the sky.
[3] ALMA is uniquely capable of detecting the faint, millimetre-wavelength light naturally emitted by atomic carbon.
[4] Because of the expansion of the
Universe the infrared radiation from W2246-0526 is redshifted to longer
millimetre wavelengths — where ALMA is very sensitive — when it is
observed from Earth.
[5] In most other quasars this ratio
is much more modest. This process of mutual interaction between the
central black hole of a galaxy and the rest of its material is known to
astronomers as feedback.
More Information
This research was presented in a paper "The Strikingly Uniform,
Highly Turbulent Interstellar Medium of The Most Luminous Galaxy in the
Universe”, by T. Díaz-Santos et al., and will be published in the
journal Astrophysical Journal Letters.
The team is composed of T. Díaz-Santos (Universidad Diego Portales,
Santiago, Chile), R. J. Assef (Universidad Diego Portales, Santiago,
Chile), A. W. Blain (University of Leicester, UK) , C.-W. Tsai (Jet
Propulsion Laboratory, California Institute of Technology, Pasadena,
California, USA) , M. Aravena (Universidad Diego Portales, Santiago,
Chile), P. Eisenhardt (Jet Propulsion Laboratory, California Institute
of Technology, Pasadena, California, USA), J. Wu (University of
California Los Angeles, California, USA), D. Stern (Jet Propulsion
Laboratory, California Institute of Technology, Pasadena, California,
USA) and C. Bridge (Jet Propulsion Laboratory, California Institute of
Technology, Pasadena, California, USA).
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Links
Contacts
Universidad Diego Portales
Santiago, Chile
Email: tanio.diaz@mail.udp.cl
Richard Hook
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org
Source: ESO
