Far-infrared emission from intracluster dust in Abell clusters

Abstract

Abstract. The ISOPHOT instrument aboard ISO has been used to observe extended FIR emission of six Abell clusters. Strip scanning measurements with crossing position angles centered on the clusters were carried out at 120 µm and 180 µm. The raw profiles of the I120 µm/I180 µm surface brightness ratio including zodiacal light show a bump towards Abell 1656 (Coma), dips towards Abell 262 and Abell 2670, and are without clear structure towards Abell 400, Abell 496, and Abell 4038. After subtraction of the zodiacal light, the bump towards Abell 1656 is still present, while the dips towards Abell 262 and Abell 2670 are no longer noticable. This indicates a localized excess of emitting material outside the Galaxy towards Abell 1656 with properties different from the galactic foreground cirrus, while the behavior in Abell 262 and Abell 2670 can be reconciled with galactic cirrus structures localized on the line-of-sight to these clusters. The excess of ≈0.2 MJy/sr seen at 120 µm towards Abell 1656 (Coma) is interpreted as being due to thermal emission from intracluster dust distributed in the hot X-ray emitting intracluster medium. The integrated excess flux within the central region of 10 -15 diameter is ≈2.8 Jy. Since the dust temperature is poorly constrained, only a rough estimate of the associated dust mass of MD ≈ 10 7 M can be derived. The associated visual extinction is negligible (AV 0.1 mag) and much smaller than claimed from optical observations. No evidence is found for intracluster dust in the other five clusters observed. The absence of any signature for intracluster dust in five clusters and the rather low inferred dust mass in Abell 1656 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 in other wavelengths regions. 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.

First detection of the Sunyaev Zel'dovich effect increment atλ< 650 μm

“…Stickel et al 2002). It is expected that, due to sputtering by energetic photons, such dust would have a very short lifetime in the ICM environment (Draine & Salpeter 1979).…”

Infrared properties of the SDSS-maxBCG galaxy clusters

“…In fact, nowadays the only claimed (and still controversial) detection of this IR emission comes from the studies on the Coma cluster of Stickel et al (1998Stickel et al ( , 2002, who measured a diffuse dust mass of M dust ≈ 10 7 M , while other attempts resulted in non detections (see, e.g., Bai et al 2007).…”

ISO’s Contribution to the Study of Clusters of Galaxies

“…Quillen et al (1999) suggested integrated emission from the cluster galaxies as the most likely source for the detected signal at the centre of Coma. Stickel et al (2002) replied that if this was indeed the case, the same signal should have been detected in all clusters observed. The absence of any signature for intra-cluster dust in five clusters and the rather low inferred dust mass in Abell 1656 indicates that intra-cluster dust is probably not responsible for the excess X-ray absorption reported in cooling flow clusters (White et al 1991).…”

“…But only upper-limits or occasionally, and with marginal significance, global or average cluster FIR emission, could constrain scenarios for the role of dust in the physics of the clusters as a whole. Stickel et al (1998Stickel et al ( , 2002) used ISOPHOT to observe extended FIR emission of six Abell clusters. Strip scanning measurements were performed at 120 µm and 180 µm.…”