Tag Archives: quasars

Combined Earth-Space radio array discovers superhot quasar interior

The uncertainty of science: Data obtained by combining four ground-based radio telescopes with the Russian orbiting RadioAstron 10-meter radio telescope have detected temperatures of 10 trillion degrees in the quasar 3C 273, a hundred times hotter than predicted possible by theory.

Supermassive black holes, containing millions to billions times the mass of our Sun, reside at the centers of all massive galaxies. These black holes can drive powerful jets that emit prodigiously, often outshining all the stars in their host galaxies. But there is a limit to how bright these jets can be – when electrons get hotter than about 100 billion degrees, they interact with their own emission to produce X-rays and Gamma-rays and quickly cool down.

Astronomers have just reported a startling violation of this long-standing theoretical limit in the quasar 3C 273. “We measure the effective temperature of the quasar core to be hotter than 10 trillion degrees!” comments Yuri Kovalev (Astro Space Center, Lebedev Physical Institute, Moscow, Russia), the RadioAstron project scientist. “This result is very challenging to explain with our current understanding of how relativistic jets of quasars radiate.”

In addition, the higher resolution of the radio images produced by this space/ground-based array was good enough to see the effect produced by the structure of the interstellar material between here and the quasar.


A quasar shuts down

Astronomers have identified the first quasar to change its energy output.

Quasars are massive, luminous objects that draw their energy from black holes. Until now, scientists have been unable to study both the bright and dim phases of a quasar in a single source. As described in an upcoming edition of the Astrophysical Journal, Yale-led researchers spotted a quasar that had dimmed by a factor of six or seven, compared with observations from a few years earlier.

It is also believed that quasars are the central supermassive black holes at the center of these very distant and ancient galaxies. Knowing how these black holes change can tell us something about the behavior of Sagittarius A*, the generally quiet central black hole in the Milky Way.


Two newly discovered supermassive black holes weigh in as the heaviest known

Two newly discovered supermassive black holes weigh in as the heaviest known.

One of the newly discovered black holes is 9.7 billion solar masses and is located in the elliptical galaxy NGC 3842, which is the brightest galaxy in the Leo cluster of galaxies that sits 320 million light years away in the direction of the constellation Leo. The second is as large or larger and sits in the elliptical galaxy NGC 4889, which is the brightest galaxy in the Coma cluster about 336 million light years from Earth in the direction of the constellation Coma Berenices.

It is believed that these heavy supermassive black holes are the kind that produced quasars in the early universe.


The most distant quasar ever found

Astronomers have found the most distant quasar ever, and are baffled by its existence.

The light from the quasar started its journey toward us when the universe was only 6% of its present age, a mere 770 million years after the Big Bang, at a redshift of about 7.1 [3]. “This gives astronomers a headache,” says lead author Daniel Mortlock, from Imperial College London. “It’s difficult to understand how a black hole a billion times more massive than the Sun can have grown so early in the history of the universe. It’s like rolling a snowball down the hill and suddenly you find that it’s 20 feet across!”


Hanny’s Voorwerp: evidence of a quasar that has turned off

Hanny’s Voorwerp: a strange object near a galaxy that has baffled astronomers is now seen as a light echo from when the galaxy’s central quasar was still active. More importantly, this is evidence that the quasar went quiescent sometime in the last 70,000 to 200,000 years. For a quasar to turn off so quickly is a surprise for astronomers.