A grand rotation curve of the Milky Way Galaxy is constructed , which covers a wide range of radius from the Galactic Center to \sim 1 Mpc , and is deconvolved into bulge , disk and halo components by least-squares fitting .
We determined the scale radii and masses of the bulge and disk to be M _ { b } = ( 1.652 \pm 0.083 ) \times 10 ^ { 10 } M _ { \odot } , a _ { b } = 0.522 \pm 0.037 kpc , M _ { d } = ( 3.41 \pm 0.41 ) \times 10 ^ { 10 } M _ { \odot } and a _ { d } = 3.19 \pm 0.35 kpc .
The dark halo was fitted by the Navaro-Frenk-White ( NFW ) density profile , \rho = \rho _ { 0 } / [ ( R / h ) ( 1 + R / h ) ^ { 2 } ] , and the fit yielded h = 12.5 \pm 0.9 kpc and \rho _ { 0 } = ( 1.06 \pm 0.14 ) \times 10 ^ { -2 } M _ { \odot } ~ { } { pc } ^ { -3 } .
The local dark matter density near the Sun at R _ { 0 } = 8 kpc is estimated to be \rho _ { 0 } ^ { \odot } = ( 6.12 \pm 0.80 ) \times 10 ^ { -3 } M _ { \odot } ~ { } { pc } ^ { -3 } = 0.235 % \pm 0.030 ~ { } { GeV~ { } cm } ^ { -3 } .
The total mass inside the gravitational boundary of the Galaxy at R \sim 385 kpc , a half distance to M31 , is estimated to be M _ { b + d + h } = ( 7.03 \pm 1.01 ) \times 10 ^ { 11 } M _ { \odot } .
This leads to the stellar baryon fraction of M _ { b + d } / M _ { b + d + h } = 0.072 \pm 0.018 .
Considering expected baryon fraction in the Local Group , we suggest that baryons in the form of hot gas are filling the dark halo with temperature of \sim 10 ^ { 6 } K and emission measure \sim 10 ^ { -5 } { pc~ { } cm ^ { 2 } } .
Such hot halo gas may share a small fraction of the observed X-ray background emission .