Strip scanning measurements with crossing position angles
have been carried out at 120 μm and 180 μm
with the ISOPHOT instrument aboard ISO to observe extended FIR
emission from six Abell clusters. The
raw I120 μm/I180 μm surface brightness ratio
including zodiacal light shows a bump towards Abell 1656 (Coma), dips
towards Abell 262 and Abell 2670, and is without an unambiguous
feature towards Abell 400, Abell 496, and Abell 4038. The subtraction
of the zodiacal light leaves the bump towards Abell 1656 still
present, while the dips towards Abell 262 and Abell 2670 are no longer
discernible. This behavior can be reconciled in Abell 1656 with a
localized excess of emitting material outside the Galaxy with
properties different from the galactic foreground cirrus, and in Abell
262 and Abell 2670 with galactic cirrus structures localized on the
line-of-sight to these clusters. At 120 μm the excess
towards Abell 1656 (Coma) is ≈ 0.2 MJy/sr, with an integrated
excess flux within the central region of 10'-15' diameter of ≈ 2.8 Jy. It is interpreted as
being due to thermal emission from intracluster dust distributed in
the hot X-ray emitting intracluster medium. Only a rough estimate of
the associated dust mass of MD ≈ 107 M⊙ can be derived, since the dust temperature is poorly constrained. The
visual extinction associated with this dust mass is negligible
(AV << 0.1 mag) and much smaller than claimed from
optical observations. No evidence for intracluster dust is found in
the other five clusters observed. The rather low inferred dust mass
in Abell 1656 together with the absence of a signature for
intracluster dust in the other clusters observed indicates
that
intracluster dust is likely not responsible for the excess X-ray
absorption seen in cooling flow clusters. These observations thereby
represent a further unsuccessful attempt in detecting the presumed final stage of the cooling flow material, in accord with quite a number of previous studies. Finally, the observed dimming of the high - redshift supernovae is unlikely be attributable to extinction caused
by dust in the intracluster or even a presumed intercluster medium.