Issue |
A&A
Volume 506, Number 3, November II 2009
|
|
---|---|---|
Page(s) | 1083 - 1094 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361/200912287 | |
Published online | 27 August 2009 |
Online Material
Appendix A: Compact sources at 610 MHz and optical counterparts
To identify optical counterparts for the radio sources we have overlaid the 610 MHz radio contours on SDSS images, see Figs. A.1, A.2, and A.3.
Source A is resolved, 13
by 19
,
with the brightest part of the emission located to the southeast. The
resolution is insufficient to classify the source, but the morphology
is consistent with a head-tail source. A spectral index gradient is
also observed towards the northwest (Sect. 5.1). An
optical counterpart is visible to the southwest of the center of the
radio source, close to the peak of the radio emission (see
Fig. A.1).
The photometric redshift (
)
of this galaxy is 0.32, consistent with being a cluster member. The
E/S0 galaxy (mag
= 18.65) has a close companion
(mag
= 21.12) about 3
to the southwest.
The spectral index of A is -0.92, between 157 and 1400 MHz,
typical for a radio galaxy. The source therefore does not seem to be
directly related to the diffuse emission within the cluster, as
suggested by Bagchi
et al. (2002).
Source B has a peculiar morphology, resembling a head-tail
galaxy. A mag
= 18.65 E/S0 counterpart is
located at
.
The direction of the tail suggest the galaxy is falling in from the
north towards the cluster center. The spectral index of the source is
-0.76 (between 241 and 610 MHz). Other sources north of the
cluster center are sources C, E, and F. Source C has a blue
star-forming galaxy (mag
)
as an optical counterpart at z=0.261 (spectroscopic
redshift). The SDSS DR6 spectrum of this galaxy shows strong emission
lines (in particular H
).
A close companion is located about 4
to the west. The
E/S0 mag
= 18.06 counterpart of source F
has a spectroscopic redshift of 0.269,
and the SDSS spectrum shows a strong Balmer break. The mag
= 20.11 optical counterpart of
E is located at
and may therefore not be associated with the cluster.
To the south of the cluster center we have sources G, H, I, J,
K, and L. Source G is probably a head-tail source, with the tail
pointing south, indicating the galaxy is also falling towards the
cluster center. The spectral index
of -1.53 is consistent with such an identification, and there is a hint
of spectral steepening towards the south. The counterpart of source G
is an E/S0 mag
= 18.35 galaxy (located at
)
with two close companions. The counterpart of source H is a blue mag
= 18.02 galaxy at
.
The spectral index
of
-1.08, quite
steep for a star-forming galaxy (e.g., Thompson
et al. 2006; Bondi et al. 2007;
Windhorst
et al. 1993), this indicates that an AGN may also be
present. The counterpart of source I is an E/S0 mag
galaxy located at
.
The counterpart of source L is an E/S0 mag
= 19.84 galaxy with
and
.
The galaxy is located roughly in the middle between RS-1 and RS-2.
Radio sources J and K are diffuse with sizes of about 10
.
Source K has no counterpart, while source J has a possible mag
,
counterpart.
However, J and K could also be the two lobes of a distant
radio galaxy.
![]() |
Figure A.1:
SDSS DR7 image color image (g, r,
and i bands) of the cluster center overlaid with
radio contours. The 610 MHz contour levels are drawn at
|
Open with DEXTER |
![]() |
Figure A.2: SDSS DR7 image color image (g, r, and i bands) of the northern part of the cluster overlaid with 610 MHz radio contours. Contours are drawn at the same levels as in Fig. A.1. |
Open with DEXTER |
![]() |
Figure A.3: SDSS DR7 image color image (g, r, and i bands) of the southern part of the cluster overlaid with 610 MHz radio contours. Contours are drawn at the same levels as in Fig. A.1. |
Open with DEXTER |
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