J/PASP/125/2 Galaxy Zoo: A catalog of overlapping galaxy pairs (Keel+, 2013)
Galaxy Zoo: A catalog of overlapping galaxy pairs for dust studies.
Keel W.C., Manning A.M., Holwerda B.W., Mezzoprete M., Lintott C.J.,
Schawinski K., Gay P., Masters K.L.
<Publ. Astron. Soc. Pac., 125, 2-16 (2013)>
=2013PASP..125....2K 2013PASP..125....2K
ADC_Keywords: Galaxy catalogs ; Morphology ; Redshifts
Keywords: galaxies
Abstract:
Analysis of galaxies with overlapping images offers a direct way to
probe the distribution of dust extinction and its effects on the
background light. We present a catalog of 1990 such galaxy pairs
selected from the Sloan Digital Sky Survey (SDSS) by volunteers of the
Galaxy Zoo project. We highlight subsamples which are particularly
useful for retrieving such properties of the dust distribution as UV
extinction, the extent perpendicular to the disk plane, and extinction
in the inner parts of disks. The sample spans wide ranges of
morphology and surface brightness, opening up the possibility of using
this technique to address systematic changes in dust extinction or
distribution with galaxy type. This sample will form the basis for
forthcoming work on the ranges of dust distributions in local disk
galaxies, both for their astrophysical implications and as the
low-redshift part of a study of the evolution of dust properties.
Separate lists and figures show deep overlaps, where the inner regions
of the foreground galaxy are backlit, and the relatively small number
of previously-known overlapping pairs outside the SDSS DR7 sky
coverage.
Description:
The bulk of this catalog consists of pairs originally selected by
volunteer members of the Galaxy Zoo project, http://www.galaxyzoo.org .
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 119 1989 Overlapping galaxy pairs
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See also:
J/ApJ/711/284 : Galaxy Zoo: AGN host galaxies (Schawinski+, 2010)
J/MNRAS/396/818 : Blue early-type galaxies in Galaxy Zoo (Schawinski+, 2009)
J/MNRAS/405/783 : Passive red spirals in Galaxy Zoo (Masters+, 2010)
J/MNRAS/410/166 : Morphological types from Galaxy Zoo 1 (Lintott+, 2011)
J/MNRAS/420/1684 : End of red sequence galaxies in Galaxy Zoo (Wong+, 2012)
http://www.galaxyzoo.org : Galaxy Zoo Home Page
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [SDSS]
6- 24 A19 --- SDSS SDSS name of the brighter member of the pair,
(JHHMMSS.ss+DDMMSS.s)
26- 43 I18 --- objID ? SDSS identification number (1)
45- 49 F5.2 mag rmag1 ? SDSS model r magnitude of brighter source
51- 55 F5.2 mag rmag2 ? SDSS model r magnitude of fainter source (2)
56- 63 F8.5 --- z1 ? Redshift of brighter source
64- 66 A3 --- n_z1 Type of brighter source (3)
69- 74 F6.4 --- z2 ? Redshift of fainter source
76- 78 A3 --- n_z2 Type of fainter source (3)
81- 84 A4 --- Type Pair type indicator (4)
86- 87 A2 --- dz [dz] large redhift difference (3)
90-119 A30 ---- Names Cross-identification(s)
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Note (1): There are pairs outside the SDSS DR8 imaging region, recognized by
their lack of an SDSS ObjID identifier.
Note (2): A value of 30.00 was assigned if the images were so strongly blended
that no estimate for the fainter galaxy was reasonable.
Note (3): these remarks include the location of the galaxy (N/S/E/W),
ctr (center?), abs/em for absorption/emission spectrum,
fg/bg for fore/background detection in a single SDSS spectrum
Note (4): Type indicators as follows:
B = the background galaxy has much smaller angular size than the
foreground disk
E = pairs containing only elliptical or S0 galaxies, as judged from the SDSS
F = spirals seen nearly face-on in front of an elliptical
or S0 background system
Phi = the spiral is seen essentially edge-on, at least partially backlit
by a smooth galaxy (Φ)
Q = the background galaxy is nearly edge-on and is projected nearly radial
to the foreground galaxy, so the backlit area spans a large range in
radius but a narrow one azimuthally within the foreground system
R = we use this code to flag a few objects which might be either
near-central superpositions or polar rings, where better imagery or
spectroscopic information would be needed to be sure
S = spiral/spiral overlaps
SE = spiral/elliptical superpositions that do not fall in one of the other
geometric categories above
X = both galaxies are seen nearly edge-on, with their disks crossing
as seen either near both nuclei or along one disk
misc = for the nineteen pairs that do not fall in any of these
geometrically-defined categories
dz = these are selected to have a known redshift difference so large
that the two galaxies will not be interacting with each other
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 26-Mar-2013