J/MNRAS/437/3883 A non-parametric method for galaxy morphology (Grootes+, 2014)
Non-parametric cell-based photometric proxies for galaxy morphology:
methodology and application to the morphologically-defined star
formation-stellar mass relation of spiral galaxies in the local universe.
Grootes M.W., Tuffs R.J., Popescu C.C., Robotham A.S.G., Seibert M.,
Kelvin L.S.
<Mon. Not. R. Astron. Soc. 437, 3883 (2014)>
=2014MNRAS.437.3883G 2014MNRAS.437.3883G
ADC_Keywords: Galaxies, nearby ; Galaxies, photometry ; Morphology
Keywords: galaxies: fundamental parameters - galaxies: photometry -
galaxies: spiral - galaxies: structure -
Abstract:
We present a non-parametric cell-based method of selecting highly pure
and largely complete samples of spiral galaxies using photometric and
structural parameters as provided by standard photometric pipelines
and simple shape fitting algorithms. The performance of the method is
quantified for different parameter combinations, using purely
human-based classifications as a benchmark. The discretization of the
parameter space allows a markedly superior selection than commonly
used proxies relying on a fixed curve or surface of separation.
Moreover, we find structural parameters derived using passbands
longwards of the g band and linked to older stellar populations,
especially the stellar mass surface density mu* and the r band
effective radius re, to perform at least equally well as parameters
more traditionally linked to the identification of spirals by means of
their young stellar populations, e.g. UV/optical colours. In
particular the distinct bimodality in the parameter mu*, consistent
with expectations of different evolutionary paths for spirals and
ellipticals, represents an often overlooked yet powerful parameter in
differentiating between spiral and non-spiral/elliptical galaxies. We
use the cell-based method for the optical parameter set including re
in combination with the Sersic index n and the i-band magnitude to
investigate the intrinsic specific star-formation rate - stellar mass
relation (ψ*-M*) for a morphologically defined volume limited
sample of local universe spiral galaxies. The relation is found to be
well described by ψ*∝M*-0.5 over the range of
109.5M☉≤M*≤1011M☉ with a mean interquartile range
of 0.4dex. This is somewhat steeper than previous determinations based
on colour-selected samples of star-forming galaxies, primarily due to
the inclusion in the sample of red quiescent disks.
Description:
Tables listing full discretization of the parameter space spanned by
the parameter combinations (log(n),log(re),Mi),
(log(n),log(re),log(mu*)), and (log(n),log(M*),log(mu*)). The
tables provide the resolution level, the front left corner of each
cell in a mathematically right-handed cartesian coordinate system, the
size of the cell in each parameter direction, the spiral fraction of
the cell's population, the relative error on the spiral fraction, the
elliptical fraction of the cell's population, and the relative error
on the elliptical fraction. Galaxies with a Galaxy Zoo DR1 (Lintott et
al., 2008MNRAS.389.1179L 2008MNRAS.389.1179L, 2011, Cat. J/MNRAS/410/166) debiased
probability (Bamford et al., 2009MNRAS.393.1324B 2009MNRAS.393.1324B) of ≥0.7 of being a
spiral are considered to be spirals, for the definition of spiral
fractions. The elliptical fraction is defined analogously.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 95 666 Cell-based discretizations for the parameter
combination (log(n),log(re),Mi)
tablea2.dat 95 666 Cell-based discretizations for the parameter
combination (log(n),log(re),log(µ*))
tablea3.dat 95 603 Cell-based discretizations for the parameter
combination (log(n),log(M*),log(µ*))
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See also:
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/435/2835 : Morphological types from Galaxy Zoo 2 (Willett+, 2013)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1 I1 --- Res [2/4] Resolution level to which cell belongs
3- 10 F8.5 [-] log(n) [-0.3/0.84] Value of Sersic index, log(n),
for front lower left corner of cell
12- 19 F8.5 [kpc] log(re) Value of effective radius, log(re), for
front lower left corner of cell
21- 28 F8.4 mag iMAG Value of absolute i band magnitude (AB system)
Mi for front lower left corner of cell
30- 37 F8.5 [-] dlog(n) Extent of cell in log(n)
39- 46 F8.5 [kpc] dlog(re) Extent of cell in log(re)
48- 55 F8.5 mag dMi Extent of cell in Mi
57- 64 F8.5 --- SPF [0/1]?=0 Spiral fraction of cell's galaxy
population (default 0.)
66- 75 E10.4 --- e_SPF [0/1.42]?=1E+6 Relative error on the cell's
spiral fraction expressed as a fraction
77- 84 F8.5 --- EF [0/1]?=0 Elliptical fraction of cell's galaxy
population (default 0.)
86- 95 E10.4 --- e_EF [0/1.42]?=1E+6 Relative error on the cell's
elliptical fraction expressed as a fraction
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 I1 --- Res [1/4] Resolution level to which cell belongs
3- 10 F8.5 [-] log(n) [-0.3/0.84] Value of Sersic index, log(n),
for front lower left corner of cell
12- 19 F8.5 [kpc] log(re) Value of effective radius, log(re), for
front lower left corner of cell
21- 28 F8.5 [Msun/kpc2] log(mu*) Value of stellar mass surface density,
log(µ*), for front lower left corner of
cell
30- 37 F8.5 [-] dlog(n) Extent of cell in log(n)
39- 46 F8.5 [kpc] dlog(re) Extent of cell in log(re)
48- 55 F8.5 [Msun/kpc2] dlog(mu*) Extent of cell in log(µ*)
57- 64 F8.5 --- SPF [0/1]?=0 Spiral fraction of cell's galaxy
population (default 0.)
66- 75 E10.4 --- e_SPF [0/1.42]?=1E+6 Relative error on the cell's
spiral fraction expressed as a fraction
77- 84 F8.5 --- EF [0/1]?=0 Elliptical fraction of cell's
galaxy population (default 0.)
86- 95 E10.4 --- e_EF [0/1.42]?=1E+6 Relative error on the cell's
elliptical fraction expressed as a fraction
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 I1 --- Res [2/4] Resolution level to which cell belongs
3- 10 F8.5 [-] log(n) [-0.3/0.84] Value of Sersic index, log(n),
for front lower left corner of cell
12- 19 F8.5 [Msun] log(M*) Value of stellar mass, log(M*), for front
lower left corner of cell
21- 28 F8.5 [Msun/kpc2] log(mu*) Value of stellar mass surface density,
log(µ*), for front lower left corner of
cell
30- 37 F8.5 [-] dlog(n) Extent of cell in log(n)
39- 46 F8.5 [Msun] dlog(M*) Extent of cell in log(M*)
48- 55 F8.5 [Msun/kpc2] dlog(mu*) Extent of cell in log(µ*)
57- 64 F8.5 --- SPF [0/1]?=0 Spiral fraction of cell's galaxy
population (default 0.)
66- 75 E10.4 --- e_SPF [0/1.42]?=1E+6 Relative error on the cell's
spiral fraction expressed as a fraction
77- 84 F8.5 --- EF [0/1]?=0 Elliptical fraction of cell's
galaxy population (default 0.)
86- 95 E10.4 --- e_EF [0/1.42]?=1E+6 Relative error on the cell's
elliptical fraction expressed as a fraction
--------------------------------------------------------------------------------
Acknowledgements:
Meiert Grootes, meiert.grootes(at)mpi-hd.mpg.de,
MPI fuer Kernphysik, Heidelberg, German
(End) M.W. Grootes [MPI fuer Kernphysik], Patricia Vannier [CDS] 05-Feb-2014