Two-dimensional spectrophotometry of the cores of X-ray luminous clusters.

The authors describe the results of a two-dimensional spectrophotometric survey of the core regions of 11 rich clusters of galaxies. Fields of view of 4arcmin.5 were observed with a CCD camera through 20 or 70 Å filters centered on wavelengths corresponding to redshifted Hα, [N II] 6583 Å, [S II] 6716, 6731 Å, [Fe X] 6374 Å, and various continuum bands. A number of these clusters have spectacular optical emission line systems in their cores. The emission line regions divide into extended ≡20 - 100 kpc systems of long linear filaments associated with the cluster core and more compact homogeneous elongated regions associated with the dominant central cluster galaxy. These results are expected when hot X-ray emitting gas cools in the cluster center. The morphology of the systems can be understood if the filaments form initially in the cooling flow, and in some cases, are subsequently accreted by the central galaxy.