Poster
Abstract
: We investigate the nature and the
physical properties of z, Y and,
J‐dropouts galaxies selected behind
the lensing cluster A2667. This field
is part of our project aimed at
identifying z~7‐10 candidates
accessible to spectroscopic studies,
based on deep photometry with ESO/VLT
HAWK‐I and FORS2 (zYJH and Ks‐band
images, AB(3 sigma)~26‐27) on a sample
of lensing clusters extracted from our
multi‐wavelength combined surveys with
SPITZER, HST, and Herschel. We have
selected 1 J‐dropout, 8 Y‐drops and 1
z‐drops within the common field of ~33
arcmin2 (effective area once corrected
for contamination and lensing
dilution). All of them are detected in
H and Ks bands in addition to J and/or
IRAC 3.6/4.5, with H(AB)~23.4 to 26.5,
and have modest magnification factors.
Although best‐fit photometric
redshifts place all these candidates
at high‐z, the contamination by low‐z
interlopers is estimated at 50‐75%
level based on previous studies, and
the comparison with the blank‐field
WIRCAM Ultra‐Deep Survey (WUDS). The
same result is obtained when
photometric redshifts include a
luminosity prior, allowing us to
remove half of the original sample as
likely z~1.7‐3 interlopers with young
stellar pulsations and strong
extinction. Two additional sources
among the remaining sample could be
identified at low‐z based on a
detection on Herschel data. Another
source, our J-drop candidate, was also
removed from our original high-z
sample using X-Shooter
observations. These low‐z
interlopers are not well described by
current templates given the large
break, and cannot be easily identified
based solely on optical and near‐IR
photometry. Given the estimated dust
extinction and high SFRs, some of them
could be also detected in the IR or
sub‐mm bands. After correction for
likely contaminants, the observed
counts at z>7.5 seem to be in
agreement with an evolving LF. We are
able to constraint the bright end of
the LF at z~8 and 9 after correction
for contamination and incompleteness.
Our results are consistent with
previous studies.
|
Bibliography
- "The
bright end of the luminosity
function at z ~ 9" Laporte et al.,
2012, A&A, 2012, 542L...31L
- "A
peculiar galaxy appears at redshift
11: properties of a
moderate-redshift interloper" Hayes,
Laporte et al., 2012, MNRAS,
425L...19H
- "Far-infrared
constraints on the contamination by
dust-obscured galaxies of high-z
dropout searches" Boone et al.,
2011, A&A, 534A...124B
- "Optical
dropout galaxies lensed by the
cluster A2667" Laporte, Pello et
al., 2011, A&A, 531A...74L
|