1,251 research outputs found
Building a Sample of Distant Clusters of Galaxies
Candidate clusters of galaxies drawn from the sample identified from the
moderately deep I-band data of the ESO Imaging Survey (EIS), have been used for
follow-up optical/infrared imaging and spectroscopic observations. The
observations were conducted to assess the nature of these candidates over a
large range of redshifts. Currently, 163 EIS candidates have (V-I) colors, 15
have (I-K) and 65 cluster fields have been observed spectroscopically. From a
preliminary analysis of these data, we find that > 65% of the candidates
studied show strong evidence of being real physical associations, over the
redshift range 0.2<z<1.1. The evidence in some cases comes directly from
spectroscopic measurements, in others indirectly from the detection of
overdensities of objects with either the same color or the same photometric
redshift, or from a combination of color and spectroscopic information.
Preliminary results also suggest that the redshift derived from the
matched-filter algorithm is a reasonable measure of the cluster's redshift,
possibly overestimating it by Delta z ~0.1, at least for systems at z<0.7.
Overdensities of red objects have been detected in over 100 candidates, 38 of
which with estimated redshifts >0.6, and six candidates in the interval
0.45<z<0.81 have either been identified directly from measured redshifts or
have been confirmed by the measurement of at least one redshift for galaxies
located along a red-sequence typical of cluster early-type galaxies. Lastly,
five candidates among those already observed in the infrared have (I-Ks) colors
consistent with them being in the redshift interval 0.8<z<1.1. The sample of
"confirmed" clusters, already the largest of its kind in the southern
hemisphere, will be further enlarged by ongoing observations.Comment: To appear in "Large Scale Structure in the X-ray Universe", ed. M.
Plionis and I. Georgantopoulos (Paris: Editions Frontieres), in pres
Multi-object spectroscopy of low redshift EIS clusters. I
We report the results of the first multi-object spectroscopic observations at
the Danish 1.54m telescope at La Silla, Chile. Observations of five cluster
candidates from the ESO Imaging Survey Cluster Candidate Catalog are described.
From these observations we confirm the reality of the five clusters with
measured redshifts of 0.11<=z<=0.35. We estimate velocity dispersions in the
range 294-621km/s indicating rather poor clusters. This, and the measured
cluster redshifts are consistent with the results of the matched filter
procedure applied to produce the Cluster Candidate Catalog.Comment: 7pages, accepted by Astronomy and Astrophysic
Multi-object spectroscopy of low-redshift EIS clusters IV. Reliability of matched-filter results at z~0.3-0.4
abridged) In this paper we present new redshifts for 747 galaxies in 23 ESO
Imaging Survey (EIS) cluster fields. We use the "gap"-technique to search for
significant overdensities in redshift space for identifying groups/clusters of
galaxies. In this way we spectroscopically confirm systems in 10 of the 23
cluster candidate fields with a matched-filter estimated redshift z_MF=0.3-0.4
and with spectroscopic redshifts in the range from z=0.158 to z=0.534. We find
that the systems identified in the present paper span a broad range of
one-dimensional velocity dispersion (175-497 km/s) and richness
(12L*<=L<=65L*). Both undersampling and contamination by substructures
contribute to the uncertainty of these measurements. From the analysis of the
colours of the galaxy populations we find that ~60% of the spectroscopically
confirmed systems have a "significant" red sequence with a colour matching
passive stellar evolution models. With this paper we complete our spectroscopic
survey of the fields of 58 EIS cluster candidates with estimated redshifts
z<=0.4. We have measured a total of 1954 galaxy redshifts in the range z=0.0065
to z=0.6706. Of the 58 systems we confirm 42 (~75%) with redshifts between
z=0.095 and z=0.534.Comment: Accepted for publication in A&A, 19 pages, 11 figure
Prevention and control of iodine deficiency in pregnant and lactating women and in children less than 2-years-old: conclusions and recommendations of the Technical Consultation
ESO Imaging Survey VII. Distant Cluster Candidates over 12 square degrees
In this paper the list of candidate clusters identified from the I-band data
of the ESO Imaging Survey (EIS) is completed using the images obtained over a
total area of about 12 square degrees. Together with the data reported earlier
the total I-band coverage of EIS is 17 square degrees, which has yielded a
sample of 252 cluster candidates in the redshift range 0.2 \lsim z \lsim 1.3.
This is the largest optically-selected sample currently available in the
Southern Hemisphere. It is also well distributed in the sky thus providing
targets for a variety of VLT programs nearly year round.Comment: 5 pages, 3 figures, submitted to Astronomy & Astrophysic
Spectroscopic confirmation of clusters from the ESO imaging survey
We measure redshifts for 67 galaxies in the field of six cluster candidates
from the ESO Imaging Survey (EIS). The cluster candidates are selected in the
EIS patches C and D among those with estimated mean redshifts between 0.5 and
0.7. The observations were made with EFOSC2 at the 3.6m ESO telescope.
In the six candidate cluster fields, we identify 19 possible sets of 2 to 7
galaxies in redshift space. In order to establish which of the 19 sets are
likely to correspond to real dense systems we compare our counts with those
expected from a uniform distribution of galaxies with given luminosity
function. In order to take into account the effect of the Large Scale
Structure, we modulate the probability computed from the luminosity function
with random samplings of the Canada-France Redshift Survey.
We find that four out of six candidate EIS clusters are likely to correspond
to real systems in redshift space (> 95 % confidence level). Two of these
systems have mean redshift in agreement with the redshift estimate given by the
matched filter algorithm. The other two systems have significantly lower
redshifts.
We discuss the implications of our results in the context of our ongoing
research projects aimed at defining high-redshift optically-selected cluster
samples.Comment: To appear in A&A, main journal -- 12 pages, 9 figure
Primary School Teachers’ Knowledge Regarding Emergency Management of Avulsed Permanent Incisors
Objective: The goal of this study was to evaluate primary school teachers' knowledge regarding emergency management of avulsed permanent incisors.Materials and Methods: The study was conducted in fifty randomly chosen primary schools from Casablanca, Morocco. All teachers of the selected schools were included in the study. The data were collected by self administered questionnaires. The questions focusedon the teachers' general characteristics, experience of avulsed teeth and the importance of emergency management. The data were analyzed using chi square test.Results: A total of 501 teachers, of which 23.6% were male and 75.4% were female, answered the questionnaire. The results showed that 44.5 % of the teachers had an experience of avulsed tooth at school, 82.82% of them knew the importance of emergency managementand 32.6% would look for a dentist for treatment of the cases. Only 15.8% would reimplant the tooth themselves. Regarding the storage media, 21.95% would keep the avulsed tooth in milk. There was no significant difference between gender and education level (p>0.05).Conclusion: This study shows school teachers' lack of knowledge regarding dental trauma and especially tooth avulsion. Therefore, the results indicated that educational programs are necessary for improvement in their level of knowledge
ESO Imaging survey: Optical Deep Public Survey
This paper presents new five passbands (UBVRI) optical wide-field imaging
data accumulated as part of the DEEP Public Survey (DPS) carried out as a
public survey by the ESO Imaging Survey (EIS) project. Out of the 3 square
degrees originally proposed, the survey covers 2.75 square degrees, in at least
one band (normally R), and 1.00 square degrees in five passbands. The median
seeing, as measured in the final stacked images, is 0.97", ranging from 0.75"
to 2.0". The median limiting magnitudes (AB system, 2" aperture, 5 sigma
detection limit) are U_(AB)=25.65, B_(AB)=25.54, V_(AB)=25.18, R_(AB) = 24.8
and I_(AB)=24.12 mag, consistent with those proposed in the original survey
design. The paper describes the observations and data reduction using the EIS
Data Reduction System and its associated EIS/MVM library. The quality of the
individual images were inspected, bad images discarded and the remaining used
to produce final image stacks in each passband, from which sources have been
extracted. Finally, the scientific quality of these final images and associated
catalogs was assessed qualitatively by visual inspection and quantitatively by
comparison of statistical measures derived from these data with those of other
authors as well as model predictions, and from direct comparison with the
results obtained from the reduction of the same dataset using an independent
(hands-on) software system. Finally to illustrate one application of this
survey, the results of a preliminary effort to identify sub-mJy radio sources
are reported. To the limiting magnitude reached in the R and I passbands the
success rate ranges from 66 to 81% (depending on the fields). These data are
publicly available at CDS.Comment: 24 pages, 26 figures. Accepted for pubblication in A&
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