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Solon
2011-May-10, 05:00 AM
I have often wondered how it was determined that matter is moving towards
black holes or AGN rather than away from them?


They infer that 1200 times the mass of our Sun is being lost each year from the galaxies with the most vigorous outflows. That is enough to strip them of their entire reserves of star-forming gas within one million to 100 million years. In other words, some galaxies could completely expel their star-forming gas in as little as a million years. Inhibiting star formation in a galaxy is known as negative feedback.

These winds could be generated by the intense emission of light and particles from young stars, or by shockwaves from the explosion of old stars. Alternatively, they may be triggered by the radiation given off as matter swirls around a black hole at the centre of the galaxy.

The fastest winds appear to be coming from the galaxies that contain the brightest 'active galactic nuclei', in which a giant black hole is feeding from its surroundings.
http://www.physorg.com/news/2011-05-raging-storms-galactic-gas.html

WayneFrancis
2011-May-10, 06:13 AM
The jets in AGN are material being shot away from the super massive black holes

But that aside....gravity is an attractive force and we can observe accretion disks. The matter heats up as it gets closer to the black hole. That is normal thermodynamics

I'm not sure how effective measuring for red/blue shift on that material would be. Gut feel is we could pry the direction of the flow from the red/blue shift.

Waiting for those with tons more knowledge them me to give a great answer :)

Cougar
2011-May-10, 11:16 PM
I have often wondered how it was determined that matter is moving towards
black holes or AGN rather than away from them?

Here's (http://arxiv.org/abs/1105.1731) the publication. Recent! Apparently this investigation only involves ULIRGs - ultra-luminous infrared galaxies, which wiki notes "show signs of recent or continuing interactions and disruptions. Many are starburst galaxies..."

I can only note that SMBHs send their particle beams only in particular directions, and at speeds approaching the speed of light, which is a lot faster than the reported 1,000 km/sec, so apparently Sturm, et al., are measuring a more general mass outflow. (Well, yeah, if they're tracing the signal from hydroxyl molecules. :doh:)

I expect "Sturm," in German, means "storm." Did the investigators position him as first author as a "prank" similar to Gamow with his Alpher, Bethe, Gamow paper? :razz:

Solon
2011-May-11, 10:15 PM
@WayneFrancis

The jets in AGN are material being shot away from the super massive black holes
I had some E-Mail conversation with Marc Berthoud a couple of years ago,
and he pointed me to this site on the M87 jets.
http://www.aoc.nrao.edu/~cwalker/M87/index.html
I don't know if the follow up at shorter sampling rates, or the different
wavelengths was ever performed, bu I don't think it was certain that the jets
were ejecting matter, or what the composition of the jets was. I also read a paper,
I'll see if I can find it, that suggested the observation of a flow in the opposite
direction, with a 5 to 15% estimated value WRT the main flow.
What I was wondering in the case of the physorg article was HOW it was measured.
I have looked at the instruments, but admit I don't know how they are used to
measure outflows.
http://pacs.mpe.mpg.de/instrument.php?lang=en

Cougar
2011-May-11, 10:59 PM
What I was wondering in the case of the physorg article was HOW it was measured.

Well, the referenced publication ("Massive molecular outflows and negative feedback in ULIRGs
observed by Herschel1-PACS") (http://arxiv.org/PS_cache/arxiv/pdf/1105/1105.1731v1.pdf) (pdf) said:





Here we report the detection of massive molecular outflows, traced by the hydroxyl molecule (OH), in far-infrared spectra of ULIRGs obtained with Herschel-PACS as part of the SHINING key project.

Further....





Here we present velocity-resolved line profiles of the OH 79μm cross ladder, ground-state doublet for a small subset of our ULIRG sample and a comparison starburst galaxy. The observations were obtained with the PACS far-infrared spectrometer (Poglitsch et al. 2010) on board Herschel (Pilbratt et al. 2010). Our data set also contains other OH transitions, but the 79μm line was observed first and is common to all objects, as it can be obtained simultaneously (in second order) with the [C II] 157μm line (in first order). At 79μm the PACS resolution is ~140 km/s.

noncryptic
2011-May-12, 11:32 AM
I have often wondered how it was determined that matter is moving towards
black holes or AGN rather than away from them?

Maybe i misunderstand your question, but I've always understood it is not a matter of either/or; it depends on the phase of evolution of the galaxy.

Solon
2011-May-14, 06:19 PM
Thanks for the replies fellas. I have looked into this a little more, and
found some explanations that make a little more sense.
Protostellar Collapse and Disk Processes
http://soral.as.arizona.edu/sofia2/node3.html
SOFIA seems to be the experiment they are hoping will detect the infow/outflow,
and there is some recent news.
SOFIA completes first flight of German science instrument
http://www.physorg.com/news/2011-04-sofia-flight-german-science-instrument.html
Here is a long paper which explains much of the star formation theory, but
explains the difficulty in observing YSOs. I'll need to take a more careful look,
but direct evidence of in-fall seems to be in very short supply.
For anyone with lots of time to spare....
http://webcache.googleusercontent.com/search?q=cache:Y5Xo1zprlSUJ:https://urresearch.rochester.edu/fileDownloadForInstitutionalItem.action%3Bjsession id%3D4D9550F62E8C9B4E0F273681D9FF5B04%3FitemId%3D1 4258%26itemFileId%3D33032+SOFIA+protostar+inflow+m easurements&cd=1&hl=en&ct=clnk&gl=ca&client=opera&source=www.google.ca