What evidence do we have that there are strong magnetic fields near the center of the galaxy?

Question

What evidence do we have that there are strong magnetic fields near the center of the galaxy?

Student response: Student

Response Answer Choices

a. strong synchrotron radiation

b. pinwheel-shaped rings of gas around Sagittarius A*

c. strong 21-cm hydrogen radiation

Answer 1

What do you mean by "strong"?  The magnetic field in the dense gas tends to be in energy equipartition with the internal energy density of the clouds.  There is some dynamo effect on the toroidal magnetic field component, that amplifies the field and causes it to "pop out" in the palloidal direction into the low density gas, as indicated by some vertical synchrotron structures.  But that field actually has a lower flux density than the field in the dense gas, whose presence is indicated by grain alignment.

The magnetic field in interstellar space is usually "frozen" into the interstellar gas, and moves with the gas, since the gas is always at least a little ionized (by cosmic rays).  The process of magnetic flux diffusing through plasma (ambipolar diffusion) is extremely slow in the interstellar medium.

One consequence of this is, that the magnetic field can be amplified by differential motions of the gas.  The gas looses kinetic energy, and the magnetic field becomes stronger.  This is called a "dynamo" and it occurs in the galactic center.  If the magnetic field becomes too strong, instabilities set in that cause it to bubble or stream away from the galactic disk (think solar flares as an analogy).  This too happens in the galactic center.

Answer 2

Cosmo,

is magnetism affected by    I = C / (D*D) as light is? i'm thinking it is, but i'm too tired to remember at this writing

magnetism as i recall is able to escape from a black hole along with gravity, the only thing that does.

would the feild effect of multiple bodies give a false signature to the magnetic spectrum with simple addition?