Spectroscopic Properties

We used the adaptive binning routine of Sanders & Fabian (2001) to produce hardness ratio maps. We define the hardness ratios $h_{1} = (1-2{\rm\, keV})/(0.3-1{\rm\, keV})$ and $h_{2} = (2-10{\rm\, keV})/(1-2{\rm\, keV})$ as the ratio of the counts in the respective energy bands and $c_{1}$ as the surface brightness in the 0.3-10 keV band in ${\rm cts\ cm^{-2}\ s^{-1}\ pixel^{-1}}$. For ICM observations, $h_1$ is mainly sensitive to absorption variations, whereas $h_2$ is a temperature diagnostic. While there is no sign of varying absorption across the field (as seen in $h_1$), the $h_2$ map clearly shows a radial temperature gradient, as would be expected in a cooling flow cluster (Fig. 2). It also shows a global temperature gradient, with the SW half of the image appearing hotter than the NE half.

We have extracted a global spectrum of A4059 from the central 90arcsec. Fitting this spectrum with a two temperature wabs*zwabs*(mekal+mekal) thermal plasma model (Galactic neutral hydrogen column fixed to $N_{\rm H,G} = 1.45\times 10^{20}\,{\rm cm^{-2}}$) results in the best fit parameters $kT_1=1.34^{+0.53}_{-0.19} {\rm\thinspace keV}$, $kT_2=3.90^{+1.19}_{-0.36} {\rm\thinspace keV}$, $Z=0.60^{+0.16}_{-0.11}$, $N_{\rm H,z}=5.36^{+0.48}_{-0.54}\times 10^{20}\,{\rm cm^{-2}}$, $\chi^2/dof=1.29$ (3 sigma error bars). A wabs*zwabs*(mkcflow + mekal) cooling flow model provides a similarly reasonable fit ($kT_{\rm 1} = 0.1^{+0.75}_{-0.1}\,{\rm keV}$, $kT_{\rm 2}=kT_{\rm {\tt mekal}}=3.80^{+0.16}_{-0.13}\,{\rm keV}$, $Z=0.71^{+0.09}_{-0.09}$, $\dot{M} = 27.6^{+6.0}_{-5.9}\, M_{\sun}{\rm\, yr^{-1}}$, $N_{\rm H,z}=5.54_{-0.40}^{+0.25} \times 10^{20}\,{\rm cm^{-2}}$, $\chi^2/dof = 1.26$).