galactic jet

[UrbanXrisis]

I read this about a black hole: "The extraordinary high pressure and temperature generated near the hole would cause some of the in-falling gas to be ejected along the direction of the black hole's spinning axis to create the galactic jet."

How is it possible for "in falling gas" able to excape the pull of a black hole and this "gas" is not virtual particles so I dont think that Hawking radiation comes into play. How are the galactic jets made?

[jcsd]

The gas is not coming from inside the hole is coming from outside it. Matter falling into a balck hole forms an accretion disc around the black hole and friction can cause it to become very hot.

[Nereid]

Gold star for an excellent question UrbanX! The mechanism for the production of the jets is an active area of research in astrophysics ... and it's not at all clear (at least to me) that we've got a good handle on it yet.

Here (http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/990923a.html) is a simple explanation. Let us know if you'd like to dive into it in more detail.

[UrbanXrisis]

"Although accretion disks have sufficient energy to eject a small fraction of the infalling material as jets, it is not clear exactly how. The accretion disks are thought to generate tangled-up magnetic field, which is probably what collimates the jets."

Hm...so they dont know how the gas excapes the force? What does "tangled-up magnetic field" mean?

[Chronos]

Magnetic fields generated by accretion discs can be enormously powerful, in theory.

[meteor]

"Astronomy picture of the day" of December 11 shows the jet of the elliptical M87. This jet can be observed in radio, optical and X-Rays and its lenght is 5000 ly! (A 1/20 part of the diameter of the Milky Way)
http://antwrp.gsfc.nasa.gov/apod/ap041211.html
Anyone knows what's the longest jet ever observed coming out from a galaxy?

[turbo]

Hi, Meteor!

Here's one that is 10,000 ly, and has a complex structure.

http://hubblesite.org/newscenter/newsdesk/archive/releases/1991/01/

[meteor]

Are you kidding me? the jets of the Giant Radio Galaxy Cygnus A (http://www.star.ucl.ac.uk/~apod/apod/ap001110.html)
measure 300000 ly each one. In comparison, the jet of your link should be called a "toy jet" :biggrin:
Though I'm not sure if the jets of Cygnus A are the longest discovered

[Chronos]

Beat me to that one, meteor. Here is another source with a radio pic
http://mamacass.ucsd.edu:8080/people/pblanco/cyga.html

[turbo]

Are you kidding me? the jets of the Giant Radio Galaxy Cygnus A (http://www.star.ucl.ac.uk/~apod/apod/ap001110.html)
measure 300000 ly each one. In comparison, the jet of your link should be called a "toy jet" :biggrin:
Though I'm not sure if the jets of Cygnus A are the longest discovered
I don't have a ready reference of galactic jet papers (long or short) but thought that you might be interested by that one. :smile: Its structure suggests to me that the mechanism by which these jets are formed can be more than just a simple "ejection along the spin axis of a black hole". Perhaps twisted or braided jets like this are formed by ejection along the orbital axis of co-orbiting black hole pairs.

[Nereid]

You mean like 3C75 (http://www.nrao.edu/imagegallery/php/level3.php?id=30), only closer to doomsday for any soft and squishy lifeforms within several kpc?

I know there have been simulations of the collision/merger of a pair of (~sol-mass) black holes; anyone know if there's been any simulations of 1 million to billion Msol pair? Maybe these are where zevatrons (http://arxiv.org/abs/astro-ph/0210477) are born?

[turbo]

You mean like 3C75 (http://www.nrao.edu/imagegallery/php/level3.php?id=30), only closer to doomsday for any soft and squishy lifeforms within several kpc?

I know there have been simulations of the collision/merger of a pair of (~sol-mass) black holes; anyone know if there's been any simulations of 1 million to billion Msol pair? Maybe these are where zevatrons (http://arxiv.org/abs/astro-ph/0210477) are born?Thank you for the links - wonderful papers behind both. Now, how can fields develop in space that are strong enough to confine these wildly excited particles while they are being accelerated to these energy levels? That question was posed in the second link, but was left open...