J/A+A/559/A2 Redshifts in the surroundings of MRC 0156-252 (Galametz+, 2013)
A large-scale galaxy structure at z=2.02 associated with the radio galaxy
MRC 0156-252.
Galametz A., Stern D., Pentericci L., De Breuck C., Vernet J.,
Wylezalek D., Fassbender R., Hatch N., Kurk J., Overzier R., Rettura A.,
Seymour N.
<Astron. Astrophys., 559, A2-2 (2013)>
=2013A&A...559A...2G 2013A&A...559A...2G
ADC_Keywords: Clusters, galaxy ; Redshifts ; Spectroscopy
Keywords: galaxies: clusters: general -
galaxies: clusters: individual: MRC 0156-252 -
galaxies: large-scale structure of Universe - individual: MRC 0156-252
Abstract:
We present the spectroscopic confirmation of a structure of galaxies
surrounding the radio galaxy MRC 0156-252 at z=2.02. The structure was
initially discovered as an overdensity of both near-infrared selected
z>1.6 and mid-infrared selected z>1.2 galaxy candidates. We used the
VLT/FORS2 multi-object spectrograph to target ∼80 high-redshift galaxy
candidates, and obtain robust spectroscopic redshifts for more than
half the targets. The majority of the confirmed sources are
star-forming galaxies at z>1.5. In addition to the radio galaxy, two
of its close-by companions (<6") also show AGN signatures. Ten
sources, including the radio galaxy, lie within |z-2.020|<0.015 (i.e.,
velocity offsets <1500km/s) and within projected 2Mpc comoving of the
radio galaxy. Additional evidence suggests not only that the galaxy
structure associated with MRC 0156-252 is a forming galaxy cluster but
also that this structure is most probably embedded in a larger-scale
structure.
Description:
We made use of the VLT/FORS2 multi-object spectrograph to target a
galaxy structure candidate in the surroundings of the radio galaxy
MRC0156-252 at z=2.02, reported in Galametz et al.
(2010A&A...522A..58G 2010A&A...522A..58G). We targeted ∼80 high-redshift galaxy
candidates. The two slit masks were observed on UT 2012 October 20
using the MXU mode of FORS2 with the blue-optimized detector and the
300V+10 grism with no order-sorting filter to cover a typical
wavelength range of 3300-6600Å (1100-2200Å at z=2). We obtained
robust spectroscopic redshifts for 45 targets between 0.2<z<3.1. Ten
were confirmed to be members of the same structure at z=2.02.
The table reports for each source its identification number,
coordinates, selection technique, spectroscopic redshift and error; it
also lists the detected absorption/emission lines along with the
galaxy type. It is a merging of Table A.1 and Table A.2 (Appendix A).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 142 10 Structure members in the redshift range 2<z<2.03
tablea2.dat 142 35 Other spectroscopic redshifts
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Byte-by-byte Description of file: tablea1.dat tablea2.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- ID [130/4439] Identification number
6- 7 I2 h RAh Right ascension (J2000) (1)
9- 10 I2 min RAm Right ascension (J2000) (1)
12- 16 F5.2 s RAs Right ascension (J2000) (1)
18 A1 --- DE- Declination sign (J2000) (1)
19- 20 I2 deg DEd Declination (J2000) (1)
22- 23 I2 arcmin DEm Declination (J2000) (1)
25- 29 F5.2 arcsec DEs Declination (J2000) (1)
31- 40 A10 --- Sel Selection criteria (3)
42- 47 F6.4 --- zsp Spectroscopic redshift
49- 54 F6.4 --- e_zsp rms uncertainty on zsp
56 A1 --- q_zsp [B] low-quality redshifts are marked by B
59-129 A71 --- lines Absoption/emission line or spectral features (2)
131-142 A12 --- Type Galaxy type (QSO, RG=Radui Galaxy, Type-2 AGN,
or star-forming galaxy)
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Note (1): Coordinates are derived from the B-band pre-imaging.
Note (2): Emission lines are marked by an asterisk.
Note (3): selection from near-IR YHK photometry (b-/r- for blue/red),
from Spitzer (IRAC) colors, galaxy companions, or Alignment
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 07-Mar-2014