We present maps and radial profiles of the gas temperature in the nearby galaxy clusters A2199 and A496 , which have the most accurate ASCA spectral data for all hot clusters .
X-ray images , temperature maps , and the presence of moderate cooling flows indicate that these clusters are relaxed and therefore can provide reliable X-ray mass measurements under the assumption of hydrostatic equilibrium and thermal pressure support .
The cluster average temperatures corrected for the presence of cooling flows are 4.8 \pm 0.2 keV and 4.7 \pm 0.2 keV ( 90 % errors ) , respectively , which are 10 % higher than the wide-beam single temperature fits .
Outside the central cooling flow regions and within r \approx 0.7 h ^ { -1 } Mpc covered by ASCA , the radial temperature profiles are similar to those of the majority of nearby relaxed clusters .
They are accurately described by polytropic models with \gamma = 1.17 \pm 0.07 for A2199 and \gamma = 1.24 _ { -0.11 } ^ { +0.08 } for A496 .
We use these polytropic models to derive accurate total mass profiles .
Within r = 0.5 h ^ { -1 } Mpc , which corresponds to a radius of overdensity 1000 , r _ { 1000 } , for these clusters ( estimated from our mass profiles ) , the total mass values are 1.45 \pm 0.15 \times 10 ^ { 14 } h ^ { -1 } M _ { \odot } and 1.55 \pm 0.15 \times 10 ^ { 14 } h ^ { -1 } M _ { \odot } .
These values are 10 % lower than those obtained assuming constant temperature .
On the other hand , the values inside a gas core radius ( 0.07 - 0.13 h ^ { -1 } Mpc ) are a factor of \mathrel { \hbox { \hbox to 0.0 pt { \hbox { \lower 4.0 pt \hbox { $ \sim$ } } } \hbox { $ > $ } } } 1.5 higher than the isothermal values .
The gas mass fraction increases significantly with radius ( by a factor of 3 between the X-ray core radius and r _ { 1000 } ) and at r _ { 1000 } reaches similar values of 0.057 \pm 0.005 h ^ { -3 / 2 } and 0.056 \pm 0.006 h ^ { -3 / 2 } for the two clusters , respectively .
Our measured total mass profiles within r _ { 1000 } are remarkably well approximated by the Navarro , Frenk , and White ‘ ‘ universal ’ ’ profile .
Since A2199 and A496 are typical relaxed clusters , the above findings should be relevant for most such systems .
In particular , the similarity of the temperature profiles in nearby clusters appears to reflect the underlying ‘ ‘ universal ’ ’ dark matter profile .
The upward revision of the mass values at small radii for the observed temperature profile compared to those derived assuming isothermality will resolve most of the discrepancy between the X-ray and strong lensing mass estimates .