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Quasars are the brightest objects in our universe. Some are trillions of times more luminous than our Sun.
Quasars seem capable of burning brilliantly for millions of years (or more), but their luminosity can vary rapidly, even over a few hours. This means these intense light sources must be small (by astronomical standards): only a few light-hours (a few billion miles) wide. The energy density produced by quasars is therefore far greater than that of normal stars.
The only processes capable of producing such energy densities are antimatter annihilation and gravitational collapse. Since there are no known substantial concentrations of antimatter in our universe, that leaves only a continuing process of gravitational collapse.
Astrophysicists believe quasars are powered by ravenous black holes prodigiously consuming gas, stars, and the odd planet. Matter falling toward a black hole forms an accretion disk, swirling around the black hole. This is somewhat similar to water swirling a drain before plunging into oblivion.
Matter in the accretion disk can reach temperatures of millions of degrees as its gravitational potential energy is converted into kinetic energy and radiation. At such high temperatures, the state of matter is plasma, a gas of free electrons and ions.
Although most of the swirling charged gas eventually falls through the black hole’s event horizon and into its central singularity, some charged particles are ejected at speeds approaching the speed of light, typically forming jets along the magnetic axes of the black hole.
Those relativistic jets of charged particles create the intense radiation that we observe as a quasar.
A black hole converts between 6% and 32% of the in-falling mass into radiated energy, compared to 0.7% for the conversion efficiency of a normal star.
At the center of nearly every major galaxy, astronomers have found a supermassive black hole that is millions or even billions of times more massive than our Sun. When such an incredible beast is surrounded by an opulent buffet of gas and stars, it becomes a quasar, an active galactic nucleus (AGN).
This artist’s conception of a quasar depicts a white jet of ultra high-speed particles emanating from the yellow accretion disk surrounding an unseen black hole.
M. Kornmesser of the ESO (European Space Organization) created this image to portray J1120+0641, a black hole that is 63 trillion times as luminous as our Sun, 2 billion times more massive, and is 13 billion light-years from Earth. Since it takes this quasar’s light 13 billion years to reach us, what our telescopes image today actually happened 13 billion years ago, 770 million years after the Big Bang.
More than 200,000 quasars have been found. A previous record-holder weighs in at 12 billion solar masses and is 350 trillion times brighter than our Sun. But that record has been broken.
In May, a team of astronomers, based in Australia and led by Christian Wolf, announced the discovery of QSO SMSS J215728.21–360215.1 (affectionately nicknamed “J2157–3602”). They report this quasar is 20 billion times more massive and 695 trillion times more luminous than our Sun, and is 12.23 billion light-years from Earth.
J2157–3602 is at the center of the image below. “Y-band” means Wolf et. al. captured this image in near-infrared light in the wavelength range 1020 ± 120 nanometers. The line labeled 120” spans an angle in the sky of 120 arcseconds (1/30th of 1 degree).
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To be this bright, Wolf estimates J2157–3602 eats one entire star every two days. He says if our own galaxy, the Milky Way, had a similar supermassive black hole at its center, it would appear 10 times brighter than the full moon, and its intense xray radiation would preclude life on Earth’s surface.
Scientists don’t fully understand the origin of such mammoth objects. Did supermassive black holes form directly from the collapse of gas soon after the Big Bang? Alternatively, did the collapse of the first stars form modest-sized black holes that subsequently grew exponentially by eating everything they could suck in? Is it really possible for something that massive to grow that fast?
Hyperluminous objects like J2157–3602 are exceedingly rare in the Universe, and are very valuable. Astronomers can use them as reference sources, or as backlighting that illuminates the intervening matter along our line-of-sight and thereby reveals its properties. With instruments that will be developed in the coming decades, Christian Wolf says such luminous beacons will directly probe the expansion of our universe in the remote past.
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Best Regards,
Robert
May 24, 2018
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