J/A+A/507/131 BzJK observations around radio galaxies (Galametz+, 2009)
Large scale structures around radio galaxies at z ∼ 1.5.
Galametz A., De Breuck C., Vernet J., Stern D., Rettura A., Marmo C.,
Omont A., Allen M., Seymour N.
<Astron. Astrophys., 507, 131-145 (2009)>
=2009A&A...507..131G 2009A&A...507..131G
ADC_Keywords: Radio sources ; Galaxies, photometry
Keywords: large scale structure of Universe - galaxies: clusters: general -
Galaxy: evolution - galaxies: individual: 7C 1756+6520 -
galaxies: individual: 7C 1751+6809
Abstract:
We explore the environments of two radio galaxies at z∼1.5,
7C 1751+6809 and 7C 1756+6520, using deep optical and near-infrared
imaging. Our data cover 15x15arcmin2 fields around the radio
galaxies. We develop and apply BzK color criteria to select cluster
member candidates around the radio galaxies and find no evidence of an
overdensity of red galaxies within 2Mpc of 7C 1751+6809. In contrast,
7C 1756+6520 shows a significant overdensity of red galaxies within
2Mpc of the radio galaxy, by a factor of 3.1±0.8 relative to the
four MUSYC fields. At small separation (r<6"), this radio galaxy also
has one z>1.4 evolved galaxy candidate, one z>1.4 star-forming galaxy
candidate, and an AGN candidate (at indeterminate redshift).
Description:
We imaged the two targets using the Bessel B-band filter of the Large
Format Camera (LFC) on the Palomar 5m Hale Telescope. We imaged the
radio galaxy fields using the z-band filter of Palomar/LFC. In
February 2005, we observed 7C 1751+6809 for 60-min under photometric
conditions. In August 2005, we observed 7C 1756+6520 for 135-min but
in non-photometric conditions.
The tables provide the B, z, J and Ks magnitudes and coordinates of
the pBzK* galaxies (red passively evolving candidates selected by
BzK=(z-K)-(B-z)←0.2 and (z-K)>2.2) for both fields. The B and z bands
were obtained using the Large Format Camera (LFC) on the Palomar 5m
Hale Telescope, and the J and Ks bands using Wide-field Infrared
Camera (WIRCAM) of the Canada-France-Hawaii Telescope (CFHT).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table5.dat 56 129 *pBzK* galaxies in 7C 1756+6520 field
table6.dat 56 106 *pBzK* galaxies in 7C 1751+6809 field
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Note on table5.dat, table6.dat: pBzK* galaxies (passive evolving galaxies
at z>1.4) are defined in the color diagram:
(z-Ks)-(B-Z)←0.2 and (z-Ks)>2.1
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Byte-by-byte Description of file: table[56].dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq Sequential number within the field
5- 6 I2 h RAh Right ascension (J2000)
8- 9 I2 min RAm Right ascension (J2000)
11- 15 F5.2 s RAs Right ascension (J2000)
17 A1 --- DE- Declination sign (J2000)
18- 19 I2 deg DEd Declination (J2000)
21- 22 I2 arcmin DEm Declination (J2000)
24- 27 F4.1 arcsec DEs Declination (J2000)
29 A1 --- l_Bmag Limit flag on Bmag
30- 34 F5.2 mag Bmag B magnitude (1)
35 A1 --- n_Bmag [a] Note on Bmag (1)
38- 42 F5.2 mag zmag z magnitude (1)
45- 49 F5.2 mag Jmag J magnitude (1)
52- 56 F5.2 mag Ksmag Ks magnitude (1)
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Note (1): Magnitudes are derived using SExtractor MAG_AUTO, with the
appropriate Galactic extinction correction applied. The color
selection for pBzK* galaxies has been made from aperture magnitudes
which give slightly different values.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 05-Feb-2010