Strange ‘unknown structure’ discovered around nearby quasar

(ORDO NEWS) — The closest quasar to the Milky Way reveals its secrets thanks to an innovative technique developed by Japanese astronomers.

A new technique for studying the brightest objects in the universe has made adjustments to scientists’ understanding of the connection between active monster black holes and slowing star formation.

Quasars are the superluminous cores of galaxies that contain extremely active supermassive black holes. The quasar’s intense radiation comes from the huge amount of hot gas that forms an accretion disk around the black hole’s vent.

Using Chile’s Atacama Large Millimeter/Submillimeter Array (ALMA), the researchers targeted quasar 3C 273.

At 2.4 billion light-years from Earth, 3C 273 is the closest quasar to the Milky Way and the first quasar ever identified.

However, the flare of the quasar’s light makes it difficult to observe the rest of its host galaxy, especially in the radio band used by ALMA.

Seeing bright and faint objects in the same image requires a property known as high dynamic range in an image.

A conventional digital camera has thousands of times the dynamic range of an image, while ALMA’s is only a few hundred times, which means ALMA has a hard time picking out faint details from brighter objects.

So a research team led by Shinya Komugi at Kogakuin University in Japan has applied a new technique they call “self-calibration.”

The trick is to reduce the flare from the quasar by using 3C 273 itself to correct for fluctuations in the Earth’s atmosphere that could interfere with ALMA’s detection of submillimeter radio waves.

This method results in an increase in contrast. ALMA observed 3C 273 at 93, 233, and 343 GHz, and the self-calibration method yielded image dynamic ranges of 85,000, 39,000, and 2,500 respectively—the highest dynamic ranges ALMA has ever achieved.

The technique revealed never-before-seen details about 3C 273’s host galaxy, including what scientists called an “unknown structure” in the discovery announcement.

Komugi’s team saw a faint band of radio emission through the host galaxy, extending tens of thousands of light years.

This radio emission comes from tens of billions to hundreds of billions of solar masses of hydrogen gas that has been ionized by the quasar’s ultraviolet and X-ray radiation.

Astronomers suspect that there is a connection between the emission of active supermassive black holes and the suppression of star formation in their host galaxies.

Radiation pouring out of the accretion disk acts as a negative feedback loop, heating up the molecular hydrogen gas so that it can no longer form stars.

However, the host galaxy 3C 273 appears to have plenty of cold molecular hydrogen gas left, and star formation continues.

So either the link between the quasar feedback and the cessation of star formation is not as specific as scientists thought, or we find 3C 273 and its galaxy in a short amount of time before the feedback effect becomes apparent.

Komugi’s team is now making similar observations of other quasars to gain a broader understanding of these processes.

“By applying the same technique to other quasars, we hope to understand how the galaxy evolves through interaction with the central core,” Komugi said in a statement.

Strange unknown structure discovered around nearby quasar

On the left is a Hubble Space Telescope image of quasar 3C 273 showing a relativistic jet of particles ejected from the black hole’s vicinity.

On the right is an ALMA image showing that the weak radio emission (blue) is not from the jet, but from ionized gas in the host galaxy.


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