By combining signals recorded from radio antennas on Earth and in space – effectively creating a telescope of almost 8-Earth-diameters in size – scientists have, for the first time, gotten a look at fine structure in the radio-emitting regions of quasar 3C273, which was the first quasar known and is still one of the brightest quasars known. The result has been startling, violating a theoretical upper temperature limit. Yuri Kovalev of the Lebedev Physical Institute in Moscow, Russia, commented:
We measure the effective temperature of the quasar core to be hotter than 10 trillion degrees!
This result is very challenging to explain with our current understanding of how relativistic jets of quasars radiate.
These results were published on March 16, 2016 in the the Astrophysical Journal.
A March 29 statement from the Max Planck Institute explained:
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.
But, once again, quasar 3C273 has surprised us, this time with a temperature much higher than that thought possible.
To obtain these new results, the international team used the space mission RadioAstron – an Earth-orbiting satellite, launched in 2011 – which employs a 10-meter radio telescope aboard a Russian satellite. RadioAstron is what astronomers call an Earth-to-space interferometer. In other words, multiple radio telescopes on Earth are linked to RadioAstron to obtain results not possible from any single instrument. In this case, the Earth-based telescopes included the 100-meter Effelsberg Telescope, the 110-meter Green Bank Telescope, the 300-meter Arecibo Observatory, and the Very Large Array. These astronomers’ statement said:
Operating together, these observatories provide the highest direct resolution ever achieved in astronomy, thousands of times finer than the Hubble Space Telescope.
The incredibly high temperatures weren’t the only surprise from this study of quasar 3C 273. The RadioAstron team also discovered an effect they said has never seen before in an extragalactic source: the image of 3C 273 has a substructure caused by the effects of peering through the dilute interstellar material of the Milky Way. Michael Johnson of the Harvard-Smithsonian Center for Astrophysics (CfA), who led the scattering study, explained:
Just as the flame of a candle distorts an image viewed through the hot turbulent air above it, the turbulent plasma of our own galaxy distorts images of distant astrophysical sources, such as quasars.
These objects are so compact that we had never been able to see this distortion before. The amazing angular resolution of RadioAstron gives us a new tool to understand the extreme physics near the central supermassive black holes of distant galaxies and the diffuse plasma pervading our own galaxy.
Bottom line: Scientists combined radio telescopes on Earth and with the Earth-orbiting radio telescope RadioAstro to learn that the famous quasar 3C273 has a core temperature hotter than 10 trillion degrees! That’s much hotter than formerly thought possible.