Massive Outburst in Spiral Galaxy NGC 660 Surprises Astronomers

Outburst in galaxy NGC 660 Surprises Astronomers

HSA image of bright “hotspots” (inset), in galaxy NGC 660.
Entire HSA image is less than a pixel in the larger optical image. CREDIT: Minchin et al., NRAO/AUI/NSF (HSA); Travis Rector, Gemini Observatory, AURA (optical).

While using the 305-meter William E. Gordon Telescope at Arecibo, researchers discovered an outburst in spiral galaxy NGC 660 that was ten times brighter than the largest supernova, or exploding star.

The surprising discovery of a massive outburst in a neighboring galaxy is giving astronomers a tantalizing look at what likely is a powerful belch by a gorging black hole at the galaxy’s center. The scientists were conducting a long-term study of molecules in galaxies, when one of the galaxies showed a dramatic change.

“The discovery was entirely serendipitous. Our observations were spread over a few years, and when we looked at them, we found that one galaxy had changed over that time from being placid and quiescent, to undergoing a hugely energetic outburst at the end,” said Robert Minchin, of Arecibo Observatory, who presented the research.

The scientists were using the National Science Foundation’s (NSF) 305-meter William E. Gordon Telescope at Arecibo for their study when they discovered the outburst in NGC 660, a spiral galaxy 44 million light-years distant in the constellation Pisces. The outburst was ten times brighter than the largest supernova, or exploding star. They reported their findings at the American Astronomical Society’s meeting in Long Beach, California.

After detecting the outburst, the team continued to observe NGC 660 with the Arecibo Telescope, and also sought to determine the cause of the outburst using an international network of telescopes to make a detailed image of the galaxy.

“High-resolution imaging is the key to understanding what’s going on,” said Emmanuel Momjian, of the National Radio Astronomy Observatory (NRAO). “We needed to know if the outburst came from a supernova in this galaxy or from the galaxy’s core. We could only do that by harnessing the high-resolution imaging power we get by joining widely-separated radio telescopes together.”

The astronomers used a network called the High Sensitivity Array (HSA), composed of the NSF’s Very Long Baseline Array (VLBA), a continent-wide system of ten radio telescopes ranging from Hawaii to the Virgin islands; the Arecibo Telescope; the NSF’s 100-meter Green Bank Telescope in West Virginia; and the 100-meter Effelsberg Radio Telescope of the Max Planck Institute for Radio Astronomy in Germany.

“By adding the large collecting area of the three big dishes to the VLBA, we got the images much more quickly. What we did with the HSA in less than half a day would have taken nearly nine days with the VLBA alone,” Momjian said.

The resulting images were more complex than the scientists expected. They thought they would see either the ring of an expanding supernova or a jet of superfast material from the galaxy’s core. Instead, they saw five sites of bright radio emission, one near the center of the galaxy and two on either side.

“The most likely explanation is that there are jets coming from the core, but they are precessing, or wobbling, and the hot spots we see are where the jets slammed into material near the galaxy’s nucleus,” said Chris Salter, of Areceibo Observatory. “To confirm this, we will continue to observe the galaxy with the HSA over the next few years,” he added.

If the jet idea is correct, the outburst probably was caused by material pulled into the supermassive black hole at the center of the galaxy. The material would form a rapidly-spinning disk around the black hole before finally falling into it, and the disk would generate jets of particles blasting outward at nearly the speed of light.

Astronomers are carefully watching a gas cloud in our own Milky Way Galaxy that is expected to fall into our Galaxy’s central black hole in the middle of this year.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc. The Arecibo Observatory is operated by SRI International under a cooperative agreement with the National Science Foundation (AST-1100968), and in alliance with Ana G. Mendez-Universidad Metropolitana, and the Universities Space Research Association.

Source: National Radio Astronomy Observatory

Image: Minchin et al., NRAO/AUI/NSF (HSA); Travis Rector, Gemini Observatory, AURA (optical)

2 Comments on "Massive Outburst in Spiral Galaxy NGC 660 Surprises Astronomers"

  1. Science says that galaxies aggregate; that is why spirals just get bigger.
    Space is so huge why do they merge?
    There are only a few (two) spirals that jet -all the rest are ellipticals.
    All the radio quasars are in ellipticals. Do quasars attract themselves to galaxies, is this the reason we discover more than one black hole in a galaxy?
    Do they attract gas or bring it with them? Are they the reason for the elliptical shape produced by the large amount of gas?
    Are quasars originally magnetars? Is this why there are only a few magnetars?
    Once ensconced in the center of a galaxy does the magnetar become a bh?
    Is the fate of all spirals to become ellipticals? Does the weight of the gas suppress the jetting because the enormous magnetism of the former magnetar cum black hole is offset by gravity?
    Does the magnetar/bh then unwind its energy without jetting into the surrounding material and die peacefully? Does this produce a starless dark?

  2. Madanagopal.V.C | February 8, 2013 at 9:46 am | Reply

    A Supernova explosion in the constellation Cancer is well recorded in history. Cancer is insignificantly bright today, whereas a century back it was a bright one in the sky. Spiral galaxies are singular galaxies mostly with their arms of stars enveloping its central core, probably a Black Hole. Nebulous galaxies are in the rising of age when the gas like hydrogen and helium condensates to form a star. Surprisingly all the galaxies are cannibals. Mighty one will devour its neighboring smaller galaxies to amass their masses to become spherical or elliptical one. For example, our own Milky Way galaxy devours its neighbors Large Magellanic Cloud and Small Magellanic Cloud. Our neighbor Andromeda galaxy is already devouring its neighbor. The central core will spew out gases when the condensation increases in the black hole in the form of jets of gases which are also recorded. Magnetic stars are the phenomena of protons and neutrons losing their shell of atoms before becoming a crumbled black hole of neutron star. Thus the kaleidoscopic spectacle in the cosmos thrills every astronomer as more and more are probed. Thank YOu.

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