We present mass and mass profile estimates for the Milky Way Galaxy using the Bayesian analysis developed by ( ) and using globular clusters ( GCs ) as tracers of the Galactic potential .
The dark matter and GCs are assumed to follow different spatial distributions ; we assume power-law model profiles and use the model distribution functions described in ( ) .
We explore the relationships between assumptions about model parameters and how these assumptions affect mass profile estimates .
We also explore how using subsamples of the GC population beyond certain radii affect mass estimates .
After exploring the posterior distributions of different parameter assumption scenarios , we conclude that a conservative estimate of the Galaxy ’ s mass within 125kpc is 5.22 \times 10 ^ { 11 } M _ { \hbox { $ \odot$ } } , with a 50 % probability region of ( 4.79 , 5.63 ) \times 10 ^ { 11 } M _ { \hbox { $ \odot$ } } .
Extrapolating out to the virial radius , we obtain a virial mass for the Milky Way of 6.82 \times 10 ^ { 11 } M _ { \hbox { $ \odot$ } } with 50 % credible region of ( 6.06 , 7.53 ) \times 10 ^ { 11 } M _ { \hbox { $ \odot$ } } ( r _ { vir } = 185 ^ { +7 } _ { -7 } \ > \mbox { kpc } ) .
If we consider only the GCs beyond 10kpc , then the virial mass is 9.02 ~ { } ( 5.69 , 10.86 ) \times 10 ^ { 11 } M _ { \hbox { $ \odot$ } } ( r _ { vir } = 198 ^ { +19 } _ { -24 } kpc ) .
We also arrive at an estimate of the velocity anisotropy parameter \beta of the GC population , which is \beta = 0.28 with a 50 % credible region ( 0.21 , 0.35 ) .
Interestingly , the mass estimates are sensitive to both the dark matter halo potential and visible matter tracer parameters , but are not very sensitive to the anisotropy parameter .