Galactic Puzzle Solved? Threads Tie It Together

[Photo:The network of filaments stretching out from galaxy NGC 1275.]

A tangle of spidery filaments stretches outward from the giant elliptical galaxy NGC 1275 as if they were dendrites of an intergalactic nerve cell.NGC 1275, located 235 million light-years from Earth near the center of a clump of galaxies known as the Perseus cluster, has posed a puzzle: How have these filaments, which are made of gas much cooler than the surrounding intergalactic cloud, persisted for perhaps 100 million years? Why haven’t they warmed, dissipated or collapsed to form stars?

Images taken by the Hubble Space Telescope, with 10 times the resolution of earlier photographs, reveal that the filaments, about 1,500 light-years wide and hundreds of thousands of light-years long, are themselves made of finer threads — smaller structures about 200 light-years wide and 20,000 light-years long. The cold gas is pushed out by waves of radiation emanating from the giant black hole at the center of the galaxy. Small is relative, of course. Each thread contains as much mass as one million Suns.

With the new information, a team led by Andrew C. Fabian, an astrophysicist at the University of Cambridge in England, calculated that weak magnetic fields, about one ten-thousandth as strong as the Earth’s field, exert enough force on the charged particles in the threads to keep them together, thus perhaps answering the puzzle.“The things tie together very well,” Dr. Fabian said.The findings appear in the Aug. 21 issue of the journal.