A quasi-stellar (star-like) radio source, a QSO, or most famously known as a quasar, was perhaps one of the most enigmatic cosmological discoveries of the 20th century. First discovered by Maarten Schmidt, the quasar was initially believed to be an abnormally blue star, unlike the typical galaxy that these surveys discovered. Moreover, the brightness of these star-like objects far surpassed the brightness of individual galaxies observed from identical distances: a single quasar could be up to 100 times more luminous than the brightest galaxies within the aforementioned region, and this disparity was astounding, to say the least.
In 1963, Dutch astronomer Maarten Schmidt was the first to define quasars as a distinct astronomic phenomenon during his observation of 3C 273. He determined that the redshift of the object was considerably large, making the calculated luminosity of the 3C 273 that much more impressive. To put it into perspective, most galaxies that are equally as far away from us as 3C 273 are around 100,000 light years in length, yet she is 100 times brighter than any of those individual galaxies. The unprecedented magnitude of its brightness in spite of its relatively small size was—at that point—inexplicable: how could a single, small object (relative to the size of a galaxy) generate that much more light than a galaxy packed with billions of stars?
The answer? We don’t know for certain, but they are believed to be supermassive black holes. I know what you’re thinking: how could a black hole, an object that is perhaps the antithesis of brightness, produce such a spectacular proportion of light? Some—albeit very few—black holes have something called an accretion disk, wherein the gasses falling into a black hole heat up as a result of friction and release energy in the form of electromagnetic radiation. While the process may not intrinsically seem as remarkable, the magnitude of a quasar’s brightness is unparalleled within the universe.
Photo Credit: quantamagazine.org