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antoniseb
2013-Sep-23, 11:22 AM
Does anyone know of an example of a galaxy that does have globular clusters, but does not have a super-massive central black hole? I'm at an early stage of working on an idea about how Globular Clusters form, and such an example would save a lot of work by showing the idea is wrong right at the beginning.

StupendousMan
2013-Sep-23, 12:12 PM
NGC 205. Maybe some of the other Andromeda satellites.

antoniseb
2013-Sep-23, 12:45 PM
NGC 205. Maybe some of the other Andromeda satellites.
OK, thanks! I'll keep my eye open for papers about NGC205 and M32. IIRC they are regarded as the remaining cores of formerly large galaxies that were stripped by M31, and so *might* have an SMBH, but so far, I don't recall any paper saying they have them, so that's an easy place to start.

chornedsnorkack
2013-Sep-23, 03:59 PM
Triangulum is devoid of black hole, yet possesses a globular cluster population (albeit modest and extending to blue):
http://www.astronomy-mall.com/Adventures.In.Deep.Space/gcm33.htm

antoniseb
2013-Sep-23, 04:36 PM
Triangulum is devoid of black hole, yet possesses a globular cluster population (albeit modest and extending to blue ...
Thanks... the NGC205 information was good, but its proximity to M31 makes it a little ambiguous as to where the GCs came from, but M33 has them, and has, at best a very small central black hole. The idea is pretty much dead (though perhaps still twitching a bit).

weltevredenkaroo
2013-Sep-23, 10:44 PM
The Fornax dSph has 5 GCs whose CMDs appear coeval and proper motions point to primordial rather than acquisitions from the LG. No SMBH known but a continuous though ragged star formation history up to <6 myr ago which is likely associated with molecular cloud shocks during its 3 apogalactic crossings in the last 9 gyr. It seems certain that a number >25 Msol stars formed out of those collisions and subsequent starform episodes. Also, Sextans B has a comparatively large GC about 6 gyr old (need to verify that number) but I haven't seen CMD data. Does the idea you're working on hinge on primordial star formation histories, or include periodic? Please post the results when you're done. Sounds like an important point.

antoniseb
2013-Sep-23, 10:58 PM
The Fornax dSph has 5 GCs whose CMDs appear coeval and proper motions point to primordial rather than acquisitions from the LG. No SMBH known but a continuous though ragged star formation history up to <6 myr ago which is likely associated with molecular cloud shocks during its 3 apogalactic crossings in the last 9 gyr.
That's pretty much a nail in the idea's coffin.

It seems certain that a number >25 Msol stars formed out of those collisions and subsequent starform episodes. Also, Sextans B has a comparatively large GC about 6 gyr old (need to verify that number) but I haven't seen CMD data. Does the idea you're working on hinge on primordial star formation histories, or include periodic? Please post the results when you're done. Sounds like an important point.
Just handwaving, the idea had to do with GCs forming from where infalling clouds had interacted with quasar jets. The idea is a little more complicated than that, but it requires a powerful jet, and a something massive enough to stop the jet to work. Five GCs around the Fornax Dwarf Spheroidal means this is not the (only) way.

weltevredenkaroo
2013-Sep-24, 03:08 PM
The consequences of gas infalling into a quasar jet is very intriguing. In effect—if I understand correctly—this would quench the jet. What other phenomenon might result from a massive gas infall, if not necessarily GC type objects? It's interesting what effect a rapid shutdown of such a powerful energy outflow would have on overall galaxy cluster morphology. It's easy to visualize what happens when a powerful jet springs into existence, but not at all easy to visually the reverse.

antoniseb
2013-Sep-24, 03:53 PM
The consequences of gas infalling into a quasar jet is very intriguing. In effect—if I understand correctly—this would quench the jet. What other phenomenon might result from a massive gas infall, if not necessarily GC type objects? It's interesting what effect a rapid shutdown of such a powerful energy outflow would have on overall galaxy cluster morphology. It's easy to visualize what happens when a powerful jet springs into existence, but not at all easy to visually the reverse.

I wasn't so much thinking about the gas hitting the source of the jet as just getting to the point where the jet momentum balanced the gas momentum, somewhere tens or hundreds of kpc from the core. We see jets hitting clouds elsewhere. My thought had been that his might explain why, long ago, there were multiple instances of GC-sized localized concentrations of matter that were able to collapse into tens of thousands of stars. Some variation on the idea might still be useful, but the GCs around Fornax pretty much kill it as I was first seeing it.

George
2013-Sep-24, 10:35 PM
Nice idea. How old are those coffin nails? Could monster jets from close neighbors in the tighter quarter's universe be adequate?