NGC 4494 is one of several intermediate-luminosity elliptical galaxies inferred to have an unusually diffuse dark matter halo .
We use the \chi ^ { 2 } -made-to-measure particle code NMAGIC to construct axisymmetric models of NGC 4494 from photometric and various kinematic data .
The extended kinematics include light spectra in multiple slitlets out to 3.5 R _ { e } , and hundreds of planetary nebulae velocities out to \simeq 7 R _ { e } , thus allowing us to probe the dark matter content and orbital structure in the halo .

We use Monte Carlo simulations to estimate confidence boundaries for the halo parameters , given our data and modelling set-up .
We find that the true potential of the dark matter halo is recovered within \Delta G ( merit function ) \mathrel { \raise 2.0 pt \hbox { \hbox to 0.0 pt { \hbox { \lower 6.0 pt \hbox { $ \sim$ } } } % \hbox { $ < $ } } } 26 ( \Delta \chi ^ { 2 } \mathrel { \raise 2.0 pt \hbox { \hbox to 0.0 pt { \hbox { \lower 6.0 pt% \hbox { $ \sim$ } } } \hbox { $ < $ } } } 59 ) at 70 % confidence level ( C.L .
) , and within \Delta G \mathrel { \raise 2.0 pt \hbox { \hbox to 0.0 pt { \hbox { \lower 6.0 pt \hbox { $% \sim$ } } } \hbox { $ < $ } } } 32 ( \Delta \chi ^ { 2 } \mathrel { \raise 2.0 pt \hbox { \hbox to 0.0 pt { \hbox { \lower 6.0 pt% \hbox { $ \sim$ } } } \hbox { $ < $ } } } 70 ) at 90 % C.L..
These numbers are much larger than the usually assumed \Delta \chi ^ { 2 } = 2.3 ( 4.6 ) for 70 % ( 90 % ) C.L .
for two free parameters , perhaps case-dependent , but calling into question the general validity of the standard assumptions used for halo and black hole mass determinations .

The best-fitting models for NGC 4494 have a dark matter fraction of about 0.6 \pm 0.1 at 5 R _ { e } ( 70 % C.L .
) , and are embedded in a dark matter halo with circular velocity \sim 200 { kms } ^ { -1 } .
The total circular velocity curve ( CVC ) is approximately flat at v _ { c } = 220 { kms } ^ { -1 } outside \sim 0.5 R _ { e } .
The orbital anisotropy of the stars is moderately radial .
These results are independent of the assumed inclination of the galaxy , and edge-on models are preferred .
Comparing with the halos of NGC 3379 and NGC 4697 , whose velocity dispersion profiles also decrease rapidly from the center outwards , the outer CVCs and dark matter halos are quite similar .
NGC 4494 shows a particularly high dark matter fraction inside \sim 3 R _ { e } , and a strong concentration of baryons in the center .