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Post Info TOPIC: 3C 326 Radio Galaxy


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RE: 3C 326 Radio Galaxy
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On Earth, thieves steal everything from diamonds to art to bags full of money. In space, gas -- fuel for making stars -- is a commodity worth the price of theft.
New observations from NASA's Spitzer Space Telescope reveal a distant, massive galaxy in the act of ripping off vast reservoirs of gas -- the equivalent of one billion suns -- from its smaller, neighbour galaxy. The stolen gas, which has become scorching hot during the heist, will likely cool down and get turned into new stars and planets.

"We may be viewing the larger galaxy in a rare, brief stage of its reincarnation from an old galaxy to a youthful one studded with brilliant stars" - Patrick Ogle of NASA's Spitzer Science Centre at the California Institute of Technology, Pasadena, California. Ogle is the lead author of a new paper on the findings in the Oct. 20 issue of the Astrophysical Journal.

The robber galaxy, called 3C 326 North, is about the mass of our Milky Way galaxy, and its victim, 3C 326 South, is about half its mass. They are close enough to perturb each other gravitationally and might eventually collide. Such galaxy mergers are common in the universe: Gas and stars in two nearby galaxies become tangled until they join up into one seamless galaxy. The case of 3C 326 is the clearest example yet of large quantities of gas being heated and siphoned from one galaxy to another.

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Title: Shocked Molecular Hydrogen in the 3C 326 Radio Galaxy System
Authors: Patrick Ogle (1), Robert Antonucci (2), P. N. Appleton (3), David Whysong (4) ((1) SSC/Caltech, (2) UCSB, (3) NHSC/Caltech, (4) NRAO/VLA)

The Spitzer spectrum of the giant FR II radio galaxy 3C 326 is dominated by very strong molecular hydrogen emission lines on a faint IR continuum. The H2 emission originates in the northern component of a double-galaxy system associated with 3C 326. The integrated luminosity in H2 pure-rotational lines is 8.0E41 erg/s, which corresponds to 17% of the 8-70 micron luminosity of the galaxy. A wide range of temperatures (125-1000 K) is measured from the H2 0-0 S(0)-S(7) transitions, leading to a warm H2 mass of 1.1E9 Msun. Low-excitation ionic forbidden emission lines are consistent with an optical LINER classification for the active nucleus, which is not luminous enough to power the observed H2 emission. The H2 could be shock-heated by the radio jets, but there is no direct indication of this. More likely, the H2 is shock-heated in a tidal accretion flow induced by interaction with the southern companion galaxy. The latter scenario is supported by an irregular morphology, tidal bridge, and possible tidal tail imaged with IRAC at 3-9 micron. Unlike ULIRGs, which in some cases exhibit H2 line luminosities of comparable strength, 3C 326 shows little star-formation activity (~0.1 Msun/yr). This may represent an important stage in galaxy evolution. Starburst activity and efficient accretion onto the central supermassive black hole may be delayed until the shock-heated H2 can kinematically settle and cool

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