How Does Dark Matter Influence Gravity in Galaxies?

[keepitmoving]

I've heard that most of dark matter is located in the outer portions of galaxies. If that is so, wouldn't the gravity from the dark matter tend to pull the galaxies apart?

 

[Chronos]

The center of mass is still within the galaxy.

 

[keepitmoving]

many thanks Chronos

 

[Chalnoth]

I've heard that most of dark matter is located in the outer portions of galaxies. If that is so, wouldn't the gravity from the dark matter tend to pull the galaxies apart?

Even if the dark matter wasn't more dense towards the center of the galaxy, the net gravitational force on the inside of a shell of matter is identically zero.