A red, green and blue image of NGC 1275, which was created by combining the data using Hubble's three Advanced Camera for Survey filters. The three images were processed with the method of Lupton et al (2004) to preserve the colour of objects avoiding saturation. The detail in the ilaments was enhanced by using the unsharp mask filter in the GNU Image Manipulation Tool.
Credit: A.C. Fabian/R.M. Johnstone/J.S. Sanders/C.J. Conselice/C.S. Crawford/J,S, Gallagher III/E.Zweibel
Scientists have discovered the forces that bind together a strange network of 100-million-year-old, rope-like gas filaments that extend from an enormous elliptical galaxy.
The filaments presented a puzzle because they should normally collapse under the pressure of the hotter surrounding gas. New images from the Hubble Space Telescope showed individual gas threads bundled together within the filaments, which allowed researchers to estimate the magnetic fields necessary to hold everything together.
"When you see a piece of rope from a distance it looks solid, but when you look closely there's a lot of threads," said Andrew Fabian, an astrophysicist at the University of Cambridge, U.K., who led the study detailed in this week's issue of the journal Nature.
Previous images of the galaxy NGC 1275 barely showed bits of the filaments, but Hubble's snapshots improved the view with 10 times more detail. Individual threads now appear to stretch about 20,000 light-years. (A light-year is the distance light will travel in a year, or about 6 trillion miles or 10 trillion kilometers.)
"It's not an astounding surprise, but the thing we can do is calculate the magnitude of the magnetic field from the size of the filaments," Fabian told SPACE.com. "Everything checks out."
The filaments may represent the most visible effect of the galaxy's central black hole on its gaseous surroundings. The black hole's high-energy jets have heated up the gas to about 70 million degrees Fahrenheit (40 million Kelvin), which in turn produces glowing bubbles that float outward from the galaxy center.
The bubbles pull colder gas outward behind them in the form of the trailing filaments. Some filaments extend in radial lines outward from the galaxy center, while others appear as horseshoe shapes.
Cold gas within the filaments could normally begin to condense and start forming stars, but the filaments' magnetic fields push against the gravitational pressure and prevent star-birth.
Fabian and his study coauthors from the U.K. and United States see NGC 1275 as just the closest example of many objects that could have filament structures.
"It's known that many distant, massive galaxies are surrounded by nebulae of gas which must be filamentary or clumpy," Fabian noted. "We think similar filaments are there in those distant objects."
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