The spectral signature of the cooling flow in Abell 478

Abstract

We present X-ray spectra of Abell 478 taken with the Ginga LAG and with the Einstein SSS. The LAC data set an upper limit of-440 M0 yr-1 on the mass deposition rate throughout the whole cluster if a value for the galactic absorption based on 21-cm observations of Hi is adopted. The SSS data strongly require an absorbing column density well in excess of that expected by scaling from 21-cm observations of galactic H i. Data from the LAC, SSS and HRI taken together imply a mass deposition rate of about 1000 M0 yr-1 with an absorption column density-4.8 x 1021 cm-2. The excess absorption may be intrinsic to the cooling flow or due to structure in the interstellar medium of the Galaxy on a scale smaller than the grid of 21-cm observations.