J/ApJ/405/94 Far-infrared emission from 5 galaxy clusters (Wise+ 1993)
Far-infrared emission from the intracluster medium.
Wise M.W., O'Connell R.W., Bregman J.N., Roberts M.S.
<Astrophys. J. 405, 94 (1993)>
=1993ApJ...405...94W 1993ApJ...405...94W
ADC_Keywords: Clusters, galaxy ; Infrared sources ; Spectra, infrared
Keywords: galaxies: clustering - infrared: galaxies - intergalactic medium
Abstract:
We have analyzed IRAS image data using a random position,
multiple-aperture photometry method to study diffuse far-infrared
emission for a sample of 56 clusters of galaxies at 60 and 100um. Five
of the clusters in the sample exhibit excess far-infrared emission,
but at low levels of significance. For A496 (Perseus) and MKW 1, this
emission appears to be associated with a strong point source: in
A2344, the observed excess is probably due to a foreground cirrus
cloud. Two clusters, A262 and A2670, show evidence for extended
diffuse emission. This emission is unlikely to be due to point sources
associated with the clusters. In these two clusters, the diffuse
emission shows evidence of being extended along the cluster's major
axis. Far-infrared maps at 60 and 100um are presented for these five
clusters. We find that contamination due to diffuse Galactic cirrus
represents the major source of uncertainty in the measurement of
far-infrared emission. The mean cluster fluxes for the sample as a
whole are 44 and 107mJy for a 4' diameter aperture at 60 and 100um,
respectively. The corresponding fluxes for a 10' diameter aperture are
138 and 253mJy at 60 and 100um. Photometry for the entire sample shows
statistical evidence for excess emission at 60um associated with
clusters in apertures 4' and 10' in diameter. This result is unlikely
to be caused by random sampling errors. The flux distributions are
analyzed for evidence that excess far-infrared radiation correlates
with cluster environmental characteristics. Although we find evidence
that poorer X-ray clusters are stronger far-infrared emitters, this
result is tentative owing to the small sample sizes involved. The
far-infrared luminosities, dust temperatures, and dust masses which
these results imply are also presented. Finally, the origin and
possible heating mechanism for dust in the intracluster medium is
discussed.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 65 238 Extracted point sources
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See also:
II/125 : IRAS catalogue of Point Sources, Version 2.0 (IPAC 1986)
II/156 : IRAS Faint Source Catalog, |b| > 10, Version 2.0 (Moshir+ 1989)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Cluster Cluster name
7- 8 I2 h RAh Right ascension (1950)
10- 11 I2 min RAm Right ascension (1950)
13- 14 I2 s RAs Right ascension (1950)
16 A1 --- DE- Declination sign
17- 18 I2 deg DEd Declination (1950)
20- 21 I2 arcmin DEm Declination (1950)
23- 24 I2 arcsec DEs Declination (1950)
26- 35 A10 --- PSC Point Source designation, generally not
in IRAS-PSC (Cat. II/125)
37- 41 F5.2 Jy F60umExt ? Extracted point source 60um flux
43- 47 F5.2 Jy F60umPSC IRAS-PSC or FSS (Cat. II/156) 60um flux
49- 53 F5.2 Jy F100umExt ? Extracted point source 100um flux
55- 59 F5.2 Jy F100umPSC IRAS-PSC or FSS 100um flux
61- 64 F4.2 --- r/rA Radius in Abell radius
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History: Prepared via OCR at CDS.
(End) James Marcout, Patricia Bauer [CDS] 26-Feb-1998