J/A+A/457/79 VIMOS VLT Deep Survey: faint type-1 AGN sample (Gavignaud+, 2006)
The VIMOS VLT Deep Survey: the faint type-1 AGN sample.
Gavignaud I., Bongiorno A., Paltani S., Mathez G., Zamorani G., Moller P.,
Picat J.P., Le Brun V., Marano B., Le Fevre O., Bottini D., Garilli B.,
Maccagni D., Scaramella R., Scodeggio M., Tresse L., Vettolani G.,
Zanichelli A., Adami C., Arnaboldi M., Arnouts S., Bardelli S.,
Bolzonella M., Cappi A., Charlot S., Ciliegi P., Contini T., Foucaud S.,
Franzetti P., Guzzo L., Ilbert O., Iovino A., Mccracken H.J., Marinoni C.,
Mazure A., Meneux B., Merighi R., Pello R., Pollo A., Pozzetti L.,
Radovich M., Zucca E., Bondi M., Busarello G., Cucciati O., De La Torre S.,
Gregorini L., Lamareille F., Mellier Y., Merluzzi P., Ripepi V., Rizzo D.,
Vergani D.
<Astron. Astrophys., 457, 79-90 (2006)>
=2006A&A...457...79G 2006A&A...457...79G
ADC_Keywords: Surveys ; Active gal. nuclei ; Redshifts ; Photometry, UBVRI
Keywords: catalogs - surveys - galaxies: active - galaxies: Seyfert -
quasars: general
Abstract:
We present the type-1 active galactic nuclei (AGN) sample extracted
from the VIMOS VLT Deep Survey's first observations of 21000 spectra
in 1.75°2. This sample, which is purely magnitude-limited and
free of morphological or color-selection biases, contains 130
broad-line AGN (BLAGN) spectra with redshift up to 5. Our data are
divided into a wide (IAB≤22.5) and a deep (IAB≤24) subsample
containing 56 and 74 objects, respectively. Because of its depth and
selection criteria, this sample is uniquely suited for studying the
population of faint type-1 AGN. Our measured surface density
(∼472±48 BLAGN per square degree with IAB≤24) is significantly
higher than that of any other optically selected sample of BLAGN with
spectroscopic confirmation. By applying a morphological and color
analysis to our AGN sample, we find that (1) ∼23% of the AGN brighter
than IAB=22.5 are classified as extended, and this percentage
increases to ∼42 for those with z<1.6; (2) a non-negligible fraction
of our BLAGN are lying close to the color-space area occupied by stars
in the u*-g' versus g'-r' color-color diagram. This leads us to the
conclusion that the classical optical-ultraviolet preselection
technique, if employed at such deep magnitudes (IAB=22.5) in
conjuction with a preselection of point-like sources, can miss up to
∼35% of the AGN population. Finally, we present a composite spectrum
of our sample of objects. While the continuum shape is very similar to
that of the SDSS composite at short wavelengths, it is much redder
than that of the SDSS composite at λ≥3000Å. We interpret
this as due to significant contamination from emission of the host
galaxies, as expected from the faint absolute magnitudes sampled by
our survey.
Description:
The B, V, R, and I observations were performed from November 1999 to
October 2000 at the 3.6m Canada-France-Hawaii Telescope, with the
CFH12K wide-field mosaic camera.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 93 115 Broad-line AGN (BLAGN) with secure redshift
(flags 14 and 13)
tablea2.dat 119 15 BLAGN with a single emission line detected and
more than one possible redshift (flag 19)
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See also:
III/250 : The VIMOS VLT deep survey (VVDS-DEEP) (Le Fevre+ 2005)
J/A+A/428/1043 : Redshifts from VIMOS VLT Deep Survey (Le Fevre+, 2004)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- Field Field
9 A1 --- Sample [dw] deep (d, IAB≤22.5) or
wide (w, IAB≤24) sample
11- 12 I2 --- Nagn Number of AGN in the field
14- 22 I9 --- VVDS Object designation number
24- 25 I2 h RAh Right ascension (J2000)
27- 28 I2 min RAm Right ascension (J2000)
30- 34 F5.2 s RAs Right ascension (J2000)
36 A1 --- DE- Declination sign (J2000)
37- 38 I2 deg DEd Declination (J2000)
40- 41 I2 arcmin DEm Declination (J2000)
43- 47 F5.2 arcsec DEs Declination (J2000)
49- 54 F6.4 --- z Redshift
56- 57 I2 --- Flag [13,14] BLAGN flag (1)
58 A1 --- n_Flag [SF] Note on Flag (2)
60- 64 F5.2 mag Imag I magnitude in AB system
66- 70 F5.2 mag Bmag ?=- B magnitude in AB system
72- 76 F5.2 mag Vmag ?=- V magnitude in AB system
78- 82 F5.2 mag Rmag ?=- R magnitude in AB system
84- 93 A10 --- Morph Morphological classification for objects
with IAB<22.5 (G1)
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Note (1): Flags as follows:
13 = BLAGN with only one line detection but with the redshift
secured from other informations such as:
- no other possible identification for the given wavelength range
- an intervening absorption-line system is detected, which this
leaves only one redshift solution for the BLAGN
- strong iron features, so-called "bumps", are detected
- a second line is marginally detected
14 = BLAGN with secure redshift measurement (i.e.: two lines or more)
Note (2): Note on Flags as follows:
F = AGN re-observed in the 3800-6500 range with FORS1 in our
follow-up program.
S = Redshift confirmed by matching the catalog from
Szokoly et al. (2004, Cat. J/ApJS/155/271).
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Byte-by-byte Description of file: tablea2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- Field Field
9 A1 --- Sample [dw] deep (d, IAB≤22.5) or
wide (w, IAB≤24) sample
11- 12 I2 --- Nagn Number of AGN in the field
14- 22 I9 --- VVDS Object designation number
24- 25 I2 h RAh Right ascension (J2000)
27- 28 I2 min RAm Right ascension (J2000)
30- 34 F5.2 s RAs Right ascension (J2000)
36 A1 --- DE- Declination sign (J2000)
37- 38 I2 deg DEd Declination (J2000)
40- 41 I2 arcmin DEm Declination (J2000)
43- 47 F5.2 arcsec DEs Declination (J2000)
49- 52 I4 0.1nm lambda Wavelength observed
54- 59 F6.4 --- z1 Redshift solution
60 A1 --- n_z1 [a-d] identification of the emission line (1)
62- 67 F6.4 --- z2 Redshift solution
68 A1 --- n_z2 [a-d] identification of the emission line (1)
70- 75 F6.4 --- z3 ? Redshift solution
76 A1 --- n_z3 [a-d] identification of the emission line (1)
78- 83 F6.4 --- z4 ? Redshift solution
84 A1 --- n_z4 [a-d] identification of the emission line (1)
86- 90 F5.2 mag Imag I magnitude in AB system
92- 96 F5.2 mag Bmag ?=- B magnitude in AB system
98-102 F5.2 mag Vmag ?=- V magnitude in AB system
104-108 F5.2 mag Rmag ?=- R magnitude in AB system
110-119 A10 --- Morph Morphological classification for objects
with IAB<22.5 (G1)
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Note (1): Note on redshift solution as follows:
a = Emission line identified as Hα
b = Emission line identified as MgII
c = Emission line identified as C III]
d = Emission line identified as CIV
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Global notes:
Note (G1): Objects in the VVDS-CDFS field are not classified. See Sect. 7.1.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 30-Apr-2007