A super bright galactic nucleus surrounding a super massive black hole is the most distant quasar ever detected and deepens a cosmic mystery.
A long time ago in a galaxy far, far away…In fact, so far away that it was actually created soon after the birth of our Universe…
“It” is actually a highly active, galactic nucleus 60 trillion times brighter than our Sun. Although even brighter objects have been detected (some nearly 100 times brighter), it may be the brightest “object” ever detected from our Universe’s remote past (remember, in space-time, distance and time are correlates; the more distant the stellar object, the older it is).
With the rather unglamorous name of ULAS J1120+0641, the object has since been identified as a quasar (which stands for “quasi-stellar radio source”). Quasars were originally thought to be just stellar objects with “high-red shift electromagnetic energy”. The theory that these objects were not actually single points (that is, stars), but rather, extended objects, such as galaxies, was first met with skepticism and controversy.
However, over the past several years, a growing consensus has emerged that these incredibly luminous objects are actually highly compacted regions of the galactic core surrounding super massive black holes. These dense regions take the form of accretion discs — vast, circular discs of stellar material and gases.
As this material gets sucked into the black hole, immense bursts (or jets) of light and energy are emitted, giving the quasar its luminosity. The ULAS quasar’s activity continues to challenge astrophysicists’ notions about how super massive black holes are formed.
A quasar’s size is estimated to be 10–10,000 times the Schwarzchild radius (sometimes called the gravitational radius), which refers to the minimum distance from the center of a spherical object such that, if the object’s mass were to collapse or compress within this radius, light could no longer escape from its surface, and so, would become invisible. The term is most often associated with the formation of black holes, but every object in the universe has such a radius.
It is thought that supermassive black holes do not form in a single event or stellar collapse, but rather, they likely start from smaller stellar black holes (or even as tiny, primordial black holes*) and grow over long time spans as their accretion discs expand. The size of such a black hole is measured in terms of solar masses. A supermassive black hole of approximately 4.5 million solar masses is believed to occupy the center of our own Milky Way Galaxy.
Supermassive black holes up to 18 billion solar masses have been observed. However, these super-sized, star-gobblers tend to be more recent in terms of their evolution. Current theory does not account for the appearance of such supermassive black holes so early in the “infancy” of the Universe. The ULAS quasar is believed to have formed a mere 800 million years or so after the Big Bang — a remarkably early date in a Universe estimated to be 13.7 billion years old.
So, right now, excitement over this discovery is being tempered by its its problematic challenge to theories of galactic evolution.
The first part of the name stands for UKIDSS Large Area Survey (ULAS); UKIDSS is the name of the survey that discovered the quasar, and also refers to the location of the quasar. The quasar is in the constellation Leo and has a red shift greater than 7. The survey team had been hunting for objects with red shift values greater than 6.5; the larger the number, the greater the red shift — indicating more time since the expansion of the Universe, and thus the further away, and older, the object is.
* Primordial or “mini” black holes garnered a good deal of publicity in 2007 when Stephen Hawking spoke of his interest in creating one upon visiting the Large Hadron Collider (LHC) at CERN, prior to its official start up, and consequently triggering a wave of public doom-saying.
Top image: ESO/M. Kornmesser
Second image: NASA