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One of the most persistent problems concerning cooling flows is the ultimate repository of the cooling gas. Recently, White et al. (1991) have found evidence for excess soft X--ray absorption in the spectra of a sample of cluster cooling flows observed with the $Einstein$ SSS. The typical excess columns of cold material (in excess to the galactic column $N_H$) are $\Delta N_H \sim 10^{21}$ cm$^{-2}$. When these columns are accumulated over the area of the cooling flow, they imply the presence of very large quantities of cold absorbing material ($M_{cold} \sim 10^{11}$--$10^{12} \, M_{\odot}$). This soft X--ray absorption could represent the first direct evidence for the large amounts of cooled material which current cooling flow models predict.
We will present results from the analysis of a 45 ksec ASCA observation of the bright, relatively nearby ($z=0.0767$) cooling flow cluster A2029. Our preliminary analysis confirms both the strong cooling flow ($\dot M \sim 370 ~M_{\odot}$ yr$^{-1}$) as well as the presence of excess absorption at a level $\sim 5$ times the standard galactic column. The spectrum is reasonably well fit by a partial covering fraction absorption model with a covering fraction of $\sim$ 0.7. Models assuming simple galactic absorption are NOT consistent with the data. There is also evidence for an absorption feature at $\sim 0.49$ keV, consistent with the redshifted O K-edge one would expect from intrinsic absorption due to cold material.
In addition, we have constructed a grid of detailed models for
the expected X--ray spectra and surface brightnesses of cluster cooling flows
including the opacity due to accumulated cold material.
These models indicate that derived values for the total cooling rate
$\dot M$ may be underestimated by $\sim 2$ assuming 100\% of the
cooling material goes into a cold, X--ray absorbing form.
We find that models with higher mass deposition in the
central regions can produce profiles comparable to the
$\dot M(
