We present ROSAT HRI data of the distant and X-ray luminous ( L _ { x } ( bol ) = 2.6 ^ { +0.4 } _ { -0.2 } \times 10 ^ { 45 } erg/sec ) cluster of galaxies 3C 295 .
We fit both a one-dimensional and a two-dimensional isothermal \beta -model to the data , the latter one taking into account the effects of the point spread function ( PSF ) .
For the error analysis of the parameters of the two-dimensional model we introduce a Monte-Carlo technique . Applying a substructure analysis , by subtracting a cluster model from the data , we find no evidence for a merger , but we see a decrement in emission South-East of the center of the cluster , which might be due to absorption . We confirm previous results by Henry & Henriksen ( 1986 ) that 3C 295 hosts a cooling flow .
The equations for the simple and idealized cooling flow analysis presented here are solely based on the isothermal \beta -model , which fits the data very well , including the center of the cluster .
We determine a cooling flow radius of 60–120 kpc and mass accretion rate of \dot { M } = 400 - 900 M _ { \odot } /y , depending on the applied model and temperature profile . We also investigate the effects of the ROSAT PSF on our estimate of \dot { M } , which tends to lead to a small overestimate of this quantity if not taken into account .
This increase of \dot { M } ( 10-25 % ) can be explained by a shallower gravitational potential inferred by the broader overall profile caused by the PSF , which diminishes the efficiency of mass accretion . We also determine the total mass of the cluster using the hydrostatic approach .
At a radius of 2.1 Mpc , we estimate the total mass of the cluster ( M _ { tot } ) to be 9.2 \pm 2.7 \times 10 ^ { 14 } M _ { \odot } .
For the gas to total mass ratio we get M _ { gas } /M _ { tot } =0.17–0.31 , in very good agreement with the results for other clusters of galaxies , giving strong evidence for a low density universe .