Black Hole Sculpts an Hourglass Galaxy
When it comes to galaxies, our home, the Milky Way, is rather neat and orderly. Other galaxies can be much more chaotic. For example, the Markarian 573 galaxy has a black hole at its center which is spewing beams of light in opposite directions, giving its inner regions more of an hourglass shape.
Our scientists have long been fascinated by this unusual structure, seen above in optical light from the Hubble Space Telescope. Now their search has taken them deeper than ever — all the way into the super-sized black hole at the center of one galaxy.
So, what do we think is going on? When the black hole gobbles up matter, it releases a form of high-energy light called radiation (particularly in the form of X-rays), causing abnormal patterns in the flow of gas.
Let’s take a closer look.
Meet Markarian 573, the galaxy at the center of this image from the Sloan Digital Sky Survey, located about 240 million light-years away from Earth in the constellation Cetus. It’s the galaxy’s odd structure and the unusual motions of its components that inspire our scientists to study it.
As is the case with other so-called active galaxies, the ginormous black hole at the center of Markarian 573 likes to eat stuff. A thick ring of dust and gas accumulates around it, forming a doughnut. This ring only permits light to escape the black hole in two cone-shaped regions within the flat plane of the galaxy — and that’s what creates the hourglass, as shown in the illustration above.
Zooming out, we can see the two cones of emission (shown in gold in the animation above) spill into the galaxy’s spiral arms (blue). As the galaxy rotates, gas clouds in the arms sweep through this radiation, which makes them light up so our scientists can track their movements from Earth.
What happens next depends on how close the gas is to the black hole. Gas that’s about 2,500 light-years from the black hole picks up speed and streams outward (shown as darker red and blue arrows). Gas that’s farther from the black hole also becomes ionized, but is not driven away and continues its motion around the galaxy as before.
Here is an actual snapshot of the inner region of Markarian 573, combining X-ray data (blue) from our Chandra X-ray Observatory and radio observations (purple) from the Karl G. Jansky Very Large Array in New Mexico with a visible light image (gold) from our Hubble Space Telescope. Given its strange appearance, we’re left to wonder: what other funky shapes might far-off galaxies take?
For more information about the bizarre structure of Markarian 573, visit http://svs.gsfc.nasa.gov/12657
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