A rare alignment between a distant galaxy and quasar (the bright center of a galaxy, powered by a super-massive black hole) provided researchers with the unique opportunity to test this theory. The quasar happens to be located in just the right place for its light to pass through the in-falling gas. Since the light from the quasar passes through the material before reaching Earth, it becomes possible to explore properties of the gas around the galaxy in detail. Without the quasar’s light acting as a probe, the surrounding gas would be undetectable.

 

By examining both the galaxy and its surrounding gas, the team could begin to unravel the question of how galaxies grow and feed star formation. Galaxies quickly deplete their gas reservoirs while creating new stars, and so must require a continuous supply of fresh gas. Researchers suspected the answer lay in the collection of surrounding cool gas via gravitational pull. Evidence of such accretion has previously been observed, but was not fully explored until now.

 

The new observations, made using two instruments — SINFONI and UVES — mounted on ESO’s VLT, showed how the galaxy itself was rotating, along with the gas composition and motion outside the galaxy. The motion, amount and composition of the gas fit with what researchers had expected to find according to the existing models. A more complete view of the galaxy will be possible with the next generation of extremely large telescopes, which will enable studies with multiple sightlines per galaxy.

 

The study was led by Nicolas Bouché of the Research Institute in Astrophysics and Planetology (IRAP) in France, along with co-authors Crystal Martin, of the University of California Santa Barbara, and Michael Murphy, of the Swinburne University of Technology in Australia. The results appeared in the July 5th issue of the journal Science.

 

(Source: Science Recorder)

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