J/A+A/572/A41 VUDS Discovery of a high-redshift protocluster (Lemaux+, 2014)
VIMOS Ultra-Deep Survey (VUDS):
Witnessing the assembly of a massive cluster at z∼3.3.
Lemaux B.C., Cucciati O., Tasca L.A.M., Le Fevre O., Zamorani G.,
Cassata P., Garilli B., Le Brun V., Maccagni D., Pentericci L., Thomas R.,
Vanzella E., Zucca E., Amorin R., Bardelli S., Capak P., Cassara L.,
Castellano M., Cimatti A., Cuby J.G., de la Torre S., Durkalec A.,
Fontana A., Giavalisco M., Grazian A., Hathi N.P., Ilbert O., Moreau C.,
Paltani S., Ribeiro B., Salvato M., Schaerer D., Scodeggio M., Sommariva V.,
Talia M., Taniguchi Y., Tresse L., Vergani D., Wang P.W., Charlot S.,
Contini T., Fotopoulou S., Gal R.R., Kocevski D.D., Lopez-Sanjuan C.,
Lubin L.M., Mellier Y., Sadibekova T., Scoville N.
<Astron. Astrophys. 572, A41 (2014)>
=2014A&A...572A..41L 2014A&A...572A..41L
ADC_Keywords: Galaxies, optical ; Photometry ; Redshifts
Keywords: galaxies: evolution - galaxies: high-redshift - galaxies: active -
galaxies: clusters: general - techniques: spectroscopic -
techniques: photometric
Abstract:
Using new spectroscopic observations obtained as part of the VIMOS
Ultra-Deep Survey (VUDS), we performed a systematic search for
overdense environments in the early universe (z>2) and report here on
the discovery of Cl J0227-0421, a massive protocluster at z=3.29. This
protocluster is characterized by both the large overdensity of
spectroscopically confirmed members, delta_gal=10.5±2.8, and a
significant overdensity in photometric redshift members. The halo mass
of this protocluster is estimated by a variety of methods to be
∼3x1014M☉ at z∼3.3, which, evolved to z=0 results in a halo
mass rivaling or exceeding that of the Coma cluster. The properties of
19 spectroscopically confirmed member galaxies are compared with a
large sample of VUDS/VVDS galaxies in lower density field environments
at similar redshifts. We find tentative evidence for an excess of
redder, brighter, and more massive galaxies within the confines of the
protocluster relative to the field population, which suggests that we
may be observing the beginning of environmentally induced quenching.
The properties of these galaxies are investigated, including a
discussion of the brightest protocluster galaxy, which appears to be
undergoing vigorous coeval nuclear and starburst activity. The
remaining member galaxies appear to have characteristics that are
largely similar to the field population. Though we find weaker
evidence of the suppression of the median star formation rates among
and differences in the stacked spectra of member galaxies with respect
to the field, we defer any conclusions about these trends to future
work with the ensemble of protostructures that are found in the full
VUDS sample.
Description:
Parameters for the 19 secure spectroscopic members and the 6
questionable spectroscopic members of Cl J0227-0421. The given
parameters are galaxy equatorial coordinates, all optical and NIR
magnitudes, spectroscopic redshifts with a corresponding confidence
flag, photometric redshifts, absolute magnitudes in the NUV, r', & J
bands, stellar mass, and star formation rate. The latter four
quantities only available when the photometry allowed for a fit.
Magnitudes are either MAG_AUTO (optical+JHK) or aperture-corrected
total magnitudes (Spitzer Channels 1 & 2) and are corrected for
Galactic extinction. Stellar masses and SFRs are calculated for a
Chabrier (2003PASP..115..763C 2003PASP..115..763C) initial mass function. Best-fit values
from the spectral energy distribution fitting are adopted. For
galaxies with a confidence flag 1 or 9, the redshift was not fixed in
the spectral energy distribution fitting process. For all other
galaxies the redshift was fixed to the spectroscopic redshift.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
specmem.dat 360 25 Protocluster spectroscopic member properties
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See also:
J/A+A/568/L8 : VUDS extreme emission line 0.2≲z≲0.9 galaxies (Amorin+, 2014)
Byte-by-byte Description of file: specmem.dat
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Bytes Format Units Label Explanations
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1- 10 I10 --- SpecID Internal VUDS/VVDS ID
12- 19 F8.6 --- zsp [3.2/3.4] Spectroscopic redshift
21- 22 I2 --- q_zsp [1/14] Spectroscopic confidence flag (1)
24- 32 F9.6 deg RAdeg Right ascension (J2000.0)
34- 43 F10.7 deg DEdeg Declination (J2000.0)
45- 51 F7.5 --- zph [0/3.5]?=9.99999 Photometric redshift (2)
53- 61 F9.6 mag umag ?=99 CFHT/Megacam u* band apparent
magnitude (2)
63- 73 F11.8 mag e_umag ?=99 u*-band mag error
75- 84 F10.7 mag gmag ?=99 CFHT/Megacam g' band apparent
magnitude (2)
86- 97 F12.9 mag e_gmag ?=99 g'-band mag error
99-107 F9.6 mag rmag ?=99 CFHT/Megacam r' band apparent
magnitude (2)
109-120 F12.9 mag e_rmag ?=99 r'-band mag error
122-130 F9.6 mag imag ?=99 CFHT/Megacam i' band apparent
magnitude (2)
132-143 F12.9 mag e_imag ?=99 i'-band mag error
145-153 F9.6 mag zmag ?=99 CFHT/Megacam z' band apparent
magnitude (2)
155-166 F12.9 mag e_zmag ?=99 z'-band mag error
168-176 F9.6 mag Jmag ?=99 CFHT/WIRCAM J band apparent
magnitude (2)
178-189 F12.9 mag e_Jmag ?=99 J-band mag error
191-199 F9.6 mag Hmag ?=99 CFHT/WIRCAM H band apparent
magnitude (2)
201-212 F12.9 mag e_Hmag ?=99 H-band mag error
214-222 F9.6 mag Kmag ?=99 CFHT/WIRCAM Ks band apparent
magnitude (2)
224-233 F10.7 mag e_Kmag ?=99 K_s-band mag error
235-241 F7.4 mag IRAC1 ?=99 Spitzer/IRAC 3.6µm band apparent
magnitude (2)
243-252 F10.7 mag e_IRAC1 ?=99 IRAC1 mag error
254-260 F7.4 mag IRAC2 ?=99 Spitzer/IRAC 4.5µm band apparent
magnitude (2)
262-271 F10.7 mag e_IRAC2 ?=99 IRAC2 mag error
273-280 F8.4 mag NUVMAG ?=99 GALEX NUV band absolute magnitude (2)
282-289 F8.4 mag rMAG ?=99 CFHT/Megacam r' band absolute
magnitude (2)
291-298 F8.4 mag JMAG ?=99 CFHT/WIRCAM J band absolute
magnitude (2)
300-307 F8.5 [Msun] logM* ?=99 Stellar mass (2)
309-316 F8.5 [Msun] E_logM* ?=99 1-σ positive error on logMass (2)
318-327 F10.7 [Msun] e_logM* ?=99 1-σ negative error on logMass (2)
329-338 F10.7 [Msun/yr] SFR ?=99 Star formation rate (2)
339-348 F10.7 [Msun/yr] E_SFR ?=99 1-σ positive error on logSFR (2)
350-359 F10.7 [Msun/yr] e_SFR ?=99 1-σ negative error on logSFR (2)
360 A1 --- Note [*] Unreliable data (3)
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Note (1): Flags 2, 3, 4, 13, and 14 are considered reliable spectroscopic
redshifts. A prefix of "1" followed by another digit indicates the presence of
a broadline active galactic nuclei. Flags 1 and 9 are considered questionable.
Note (2): A value of 99 or 9.99999 indicates that the quantity was not
measured/computed.
Note (3): *: Object 20463884 is too close to a bright star for the measured
photometry to be reliable.
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Acknowledgements:
Brian C. Lemaux, brian.lemaux(at)lam.fr
(End) Brian C. Lemaux [LAM, Marseille], Patricia Vannier [CDS] 28-Aug-2014