Access to Astronomical Catalogues

← Click to display the menu
J/ApJ/723/737  Catalog of variability selected AGNs in GOODS  (Villforth+, 2010)

A new extensive catalog of optically variable active galactic nuclei in the GOODS fields and a new statistical approach to variability selection. Villforth C., Koekemoer A.M., Grogin N.A. <Astrophys. J., 723, 737-754 (2010)> =2010ApJ...723..737V
ADC_Keywords: Active gal. nuclei ; QSOs ; Photometry ; Redshifts Keywords: catalogs - galaxies: active - quasars: general Abstract: Variability is a property shared by practically all active galactic nuclei (AGNs). This makes variability selection a possible technique for identifying AGNs. Given that variability selection makes no prior assumption about spectral properties, it is a powerful technique for detecting both low-luminosity AGNs in which the host galaxy emission is dominating and AGNs with unusual spectral properties. In this paper, we will discuss and test different statistical methods for the detection of variability in sparsely sampled data that allow full control over the false positive rates. We will apply these methods to the GOODS North and South fields and present a catalog of variable sources in the z band in both GOODS fields. Out of the 11 931 objects checked, we find 155 variable sources at a significance level of 99.9%, corresponding to about 1.3% of all objects. After rejection of stars and supernovae, 139 variability-selected AGNs remain. Their magnitudes reach down as faint as 25.5mag in z. Spectroscopic redshifts are available for 22 of the variability-selected AGNs, ranging from 0.046 to 3.7. The absolute magnitudes in the rest-frame z band range from ~-18 to -24, reaching substantially fainter than the typical luminosities probed by traditional X-ray and spectroscopic AGN selection in these fields. Therefore, this is a powerful technique for future exploration of the evolution of the faint end of the AGN luminosity function up to high redshifts. Description: Basic properties of the sample of variability selected AGN in the GOODS North and South Fields. Objects identified as Stars are included in this catalogue but marked as 'Star' in the comment field. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table5.dat 121 155 Basic properties of variability selected AGNs
See also: II/261 : GOODS initial results (Giavalisco+, 2004) J/ApJ/640/603 : Catalog of AGNs in the GOODS fields (Treister+, 2006) Byte-by-byte Description of file: table5.dat
Bytes Format Units Label Explanations
1- 19 A19 --- GOODS GOODS ID (, J2000) 21- 24 A4 --- n_GOODS Object detected in other studies (1) 26- 36 F11.7 deg RAdeg Right ascension in decimal degrees (J2000.0) 38- 48 F11.7 deg DEdeg Declination in decimal degrees (J2000.0) 50- 54 F5.2 mag zmag Magnitude in F850LP band 56- 59 F4.2 --- Stel [0/1] Stellarity Measure ClassStar from Sextractor (1 is point like, 0 is extended) 61- 65 F5.2 --- C C-Statistics (2) 67- 71 F5.2 % Var Variability Strength 73- 78 A6 --- Det Detection significance (3) 80-104 A25 --- Comment Description of Morphology or Identification as Star 105 A1 --- r_Comment Reference for Comment (4) 107-112 F6.4 --- z ?=- Spectroscopic redshift 113 A1 --- q_z [LSTN] Quality of redshift (5) 114 A1 --- r_z [fj] Redshift reference if not Popesso et al. (2009A&A...494..443P) (6) 116-121 F6.2 mag zMAG ?=- Absolute magnitude in restframe F850LP band only if redshift known
Note (1): Abbreviations used as follows: C = Cohen et al. (2006ApJ...639..731C) T = Trevese et al. (2008, Cat. J/A+A/488/73) KS = Klesman & Sarajedini (2007ApJ...665..225K) Note (2): Measure of Variability, this value was used to determine which objects are variable. Note (3): Catalog ID: Normal = this object is in the catalog with 99.9% significance Clean = this object is in the catalog with 99.99% significance Note (4): References as follows: a = Popesso et al., 2009A&A...494..443P b = Wolf et al., 2008A&A...492..933W c = Groenewegen et al., 2002, Cat. J/A+A/392/741 d = Santini et al., 2009, Cat. J/A+A/504/751 e = Hatziminaoglou et al., 2002, Cat. J/A+A/384, 81 g = Straughn et al., 2006, Cat. J/ApJ/639/724 h = Taylor et al., 2009, Cat. J/ApJ/639/724 i = Mendez & Guzman, 1998A&A...333..106M k = Riess et al., 2004, Cat. J/ApJ/607/665 Note (5): Notes on z as follows: L = likely redshift S = secure redshift T = tentative redshift N = if spectroscopy was performed but no redshift could be derived Note (6): References as follows: f = Szokoly et al. 2004, Cat. J/ApJS/155/271 j = Hornschemeier et al., 2001, Cat. J/ApJ/554/742
Acknowledgements: Carolin Villforth, villfort(at),
(End) Carolin Villforth [STScI, USA], Patricia Vannier [CDS] 09-Nov-2010
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

catalogue service