J/ApJS/179/306 Radio galaxy morphologies (Russell+, 2008)
Optical morphologies of millijansky radio galaxies observed by the
Hubble Space Telescope and in the very large array FIRST survey.
Russell J., Ryan R.E.Jr, Cohen S.H., Windhorst R.A., Waddington I.
<Astrophys. J. Suppl. Ser., 179, 306-318 (2008)>
=2008ApJS..179..306R 2008ApJS..179..306R (SIMBAD/NED BibCode)
ADC_Keywords: Photometry, HST ; Galaxies, radio ; Morphology
Keywords: galaxies: starburst - radio continuum: galaxies
Abstract:
We report on a statistical study of 51 radio galaxies at the
millijansky flux level selected from the Faint Images of the Radio Sky
at Twenty cm survey, including their optical morphologies and
structure obtained with the Hubble Space Telescope (HST). Our optical
imaging is significantly deeper (∼2mag) than previous studies with the
superior angular resolution of space-based imaging. We that find 8/51
(16%) of the radio sources have no optically identifiable counterpart
to AB∼24mag. For the remaining 43 sources, only 25 are sufficiently
resolved in the HST images to reliably assign a visual classification:
15 (60%) are elliptical galaxies, two (8%) are late-type spiral
galaxies, one (4%) is an S0, three (12%) are pointlike objects
(quasars), and four (16%) are merger systems. We find a similar
distribution of optical types with measurements of the Sersic index.
Description:
We begin by correlating the positions from the FIRST catalog with the
HST WFPC2 Archive. We excise 300x300 pixel "postage stamp" images from
the astrometrically corrected and stacked WFPC2 mosaics centered on
each FIRST source position.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 73 43 Targeted sources removed from sample
table3.dat 32 8 Unidentified radio sources
table4.dat 79 54 Flux results
table5.dat 76 51 Morphological and structural results
--------------------------------------------------------------------------------
See also:
B/hst : HST Archived Exposures Catalog (STScI, 2007)
VIII/71 : The FIRST Survey Catalog, Version 03Apr11 (Becker+ 2003)
II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- FIRST Radio source name (JHHMMSS.s-DDMMSS) (G1)
18- 27 F10.6 deg RAdeg Right ascension in degree (J2000)
29- 38 F10.6 deg DEdeg Declination in degree (J2000)
40- 43 F4.2 mJy S1.4GHz Integrated flux at 1.4GHz from FIRST,
cat. VIII/71
45- 73 A29 --- WFPC2 WFPC2 target (targname) (1)
--------------------------------------------------------------------------------
Note (1): This is the header keyword for the field target from the WFPC2 images.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- FIRST Radio source name (JHHMMSS.s-DDMMSS) (G1)
18- 22 A5 --- Passband F814W or F606W bandpass
24- 27 F4.1 mag Limit Limiting I or V band AB magnitude (1)
29- 32 F4.2 mJy S1.4GHz Integrated flux at 1.4GHz from FIRST cat.
--------------------------------------------------------------------------------
Note (1): The limiting AB magnitude in specified filter given as 50%
completeness limit following Snigula et al. (2002MNRAS.336.1329S 2002MNRAS.336.1329S).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- FIRST Radio source name (JHHMMSS.s-DDMMSS) (G1)
18 A1 --- Band [VI] V or I band (1)
20- 24 F5.2 mag mag ?=- V or I band magnitude
26- 30 F5.2 mag/arcsec2 SB ?=- Surface brightness within effective
radius (see Re in table 5)
32- 35 F4.2 mJy S1.4GHz Integrated flux at 1.4GHz from FIRST cat.
37- 40 F4.1 mag Depth ?=- Field depth (2)
42- 46 F5.2 --- LR ?=- Likelihood ratio (3)
48- 52 F5.2 mag i'mag ?=- SDSS-DR5 i' band magnitude (4)
54- 57 F4.2 mag e_i'mag ? Error in i'mag
59- 63 F5.2 mag (g'-r') ?=- SDSS-DR5 (g'-r') color index (4)
65- 68 F4.2 mag e_(g'-r') ? Error in (g'-r') color index
70- 74 F5.2 mag (r'-i') ?=- SDSS-DR5 (r'-i') color index (4)
76- 79 F4.2 mag e_(r'-i') ? Error in (r'-i') color index
--------------------------------------------------------------------------------
Note (1): V and I refer to the HST WFPC2 bandpasses F606W or F814W, respectively.
Note (2): The 50% completeness limit as determined by the Snigula et al.
(2002MNRAS.336.1329S 2002MNRAS.336.1329S) method (see Section 2.4).
Note (3): The likelihood ratio (LR) technique described by de Ruiter et al.
(1977A&AS...28..211D 1977A&AS...28..211D). Objects with LR≥2 are a positive
identification. (See section 2.4 for the complete equation)
Note (4): Obtained from SDSS DR5 (Adelman-McCarthy et al., 2007, Cat.
II/276, superseded by Cat. II/294, SDSS-DR7).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- FIRST Radio source name (JHHMMSS.s+DDMMSS) (G1)
18- 21 F4.2 arcsec Re ?=- Effective radius (1)
23- 26 F4.2 --- n ?=- The Sersic index (2)
28- 31 F4.2 --- e_n ? Error in n
33- 36 F4.2 --- Chi2V ?=- Reduced Chi2ν (3)
38- 41 F4.1 --- ANNt ?=- Artificial Neural Network type
classification (4)
43- 56 A14 --- VisType Morphology of optical counterpart (5)
58- 76 A19 --- WFPC2 WFPC2 target (6)
--------------------------------------------------------------------------------
Note (1): Half-light radius as measured by LMORPHO (Odewahn et al. 1996).
Note (2): Defined by eq. (6): I(r)=Ieexp{-bn[(R/Re)1/n-1]} where Ie is
the intensity at the effective radius Re and bn is a constant
defined in terms of n, which describes the shape of the profile (e.g.,
Graham & Driver, 2005PASA...22..118G 2005PASA...22..118G).
Note (3): Reduced chi2ν between the observed profile and below eq. (6).
Note (4): Artificial Neural Network type classification as measured by LMORPHO
(Odewahn et al., 1996ApJ...472L..13O 1996ApJ...472L..13O).
Note (5): Morphology of optical counterpart including flags as follows:
E = Elliptical galaxy
SBb-SBc = Late-type spiral galaxy
S0 = S0 galaxy
ps = pointlike object (quasar)
Merger = merger system
x = objects too small to assign a reliable morphology
xC = object is compact
xE = object is extended
UNID = unidentified
Note (6): This is the header keyword for the field target from the WFPC2 images,
which helped us assess the "randomness" of each WFPC2 field.
--------------------------------------------------------------------------------
Global Notes:
Note (G1): The name of the source as per IAU recommendations, as used by FIRST:
Jhhmmss.s+ddmmss in which the coordinates are equinox J2000.0 and are
truncated (Becker et al., 1995ApJ...450..559B 1995ApJ...450..559B).
History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 16-Sep-2009