J/A+A/631/A94 Avg pitch angles & spiral amplitudes in S4G (Diaz-Garcia+, 2019)
The shapes of spiral arms in the S4G survey and their connection with
stellar bars.
Diaz-Garcia S., Salo H., Knapen J.H., Herrera-Endoqui M.
<Astron. Astrophys. 631, A94 (2019)>
=2019A&A...631A..94D 2019A&A...631A..94D (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Galaxies, IR ; Galaxies, photometry ;
Galaxies, rotation ; Galaxy catalogs
Keywords: galaxies: structure - galaxies: evolution - galaxies: statistics -
galaxies: spiral - galaxies: fundamental parameters -
galaxies: photometry
Abstract:
Spiral galaxies are very common in the local Universe, but their
formation, evolution, and interplay with bars remain poorly understood
after more than a century of astronomical research on the topic.
We use a sample of 391 nearby galaxies from the S4G survey to
characterise the winding angle and amplitude of spiral arms as a
function of disc properties, such as bar strength, in all kinds of
spirals (grand-design, multi-armed, and flocculent).
We derived global pitch angles in 3.6um de-projected images from i)
average measurements of individual logarithmic spiral segments, and
ii) for a subsample of 32 galaxies, from 2-D Fourier analyses. The
strength of spirals was quantified from the tangential-to-radial force
ratio and from the normalised m=2 Fourier density amplitudes.
In galaxies with more than one measured logarithmic segment, the
spiral pitch angle varies on average by ∼10° between segments, but
by up to ≥15-20°. The distribution of the global pitch angle
versus Hubble type (T) is very similar for barred and non-barred
galaxies when 1≤T≤5. Most spiral galaxies (>90%) are barred for T>5.
The pitch angle is not correlated with bar strength, and only weakly
with spiral strength. The amplitude of spirals is correlated with bar
strength (and less tightly, with bar length) for all types of spirals.
The mean pitch angle is hardly correlated with the mass of the
supermassive black hole (estimated from central stellar velocity
dispersion), with central stellar mass concentration, or with shear,
questioning previous results in the literature using smaller samples.
We do not find observational evidence that spiral arms are driven by
stellar bars or by invariant manifolds. Most likely, discs that are
prone to the development of strong bars are also reactive to the
formation of prominent spirals, explaining the observed coupling
between bar and spiral amplitudes.
Description:
We provide the tabulated average pitch angles and amplitudes of the
spiral arms of a sample of 391 not-highly inclined spiral galaxies
(i<65° in Salo et al. 2015, Cat. J/ApJS/219/4) in the Spitzer
Survey of Stellar Structure in Galaxies (Sheth et al. 2010, Cat.
J/PASP/122/1397). See Table A.1. in the paper.
For each galaxy, we list the mean and median spiral pitch angle (and
its dispersion), calculated from the fits of the logarithmic segments
carried out by Herrera-Endoqui et al. (2015A&A...582A..86H 2015A&A...582A..86H)
using 3.6um images. We also provide the mean weighted by the arc
length of the logarithmic segments, and the mean of the innermost
segments. In addition, we tabulate the mean spiral strength, and the
dispersion, calculated from gravitational torques (QT=FT/) and m=2
Fourier amplitudes (A2) (from Diaz-Garcia et al.,
2016A&A...587A.160D 2016A&A...587A.160D) evaluated at the radial ranges where the pitch
angle of logarithmic segments were fitted, also including the dark
matter halo in the force calculation.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 153 391 Average pitch angles and spiral amplitudes
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See also:
J/PASP/122/1397 : Spitzer Survey of Stellar Structure in Galaxies (Sheth+ 2010)
J/A+A/582/A86 : Catalogue of features in the S4G (Herrera-Endoqui+, 2015)
J/ApJS/217/32 : S4G galaxy morphologies in the CVRHS system (Buta+, 2015)
J/ApJS/219/4 : S4G pipeline 4: multi-component decompositions (Salo+, 2015)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Galaxy Galaxy identification (Galaxy)
14 A1 --- Type [GMF] Spiral types according to Buta et al.
(2015, Cat J/ApJS/217/32) (Type) (1)
16 I1 --- Flag [1/2] Quality flag for the spiral fit from
Herrera-Endoqui et al. (2015,
Cat. J/A+A/582/A86) (Flag) (2)
18 I1 --- N Number of logarithmic segments fitted by
Herrera-Endoqui et al.
(2015, Cat. J/A+A/582/A86) (N)
23- 27 F5.2 deg Pmean Mean pitch angle (P_mean)
29- 36 F8.2 deg e_Pmean ?=-9999.99 Standard deviation of the mean
pitch angle (ErrPmean)
38- 45 F8.2 deg s_Pmean ?=-9999.99 Standard deviation of the pitch
angle (SD_P)
50- 54 F5.2 deg Pmedian Median pitch angle (P_median)
59- 63 F5.2 deg Pinner Mean pitch angle of innermost spiral
segments (P_inner)
65- 72 F8.2 deg e_Pinner ?=-9999.99 Standard deviation of the mean
of inner pitch angle (ErrPinner)
77- 81 F5.2 deg Pweighted Mean pitch angle weighted by the arc length
of the logarithmic segments (P_weighted)
83- 90 F8.2 deg s_Pweighted ?=-9999.99 Weighted standard deviation of
the pitch angle (SDPweighted)
92- 99 F8.2 --- QTspiral ?=-9999.99 Mean gravitational torque
(QT=FT/) of the spiral arms
(QT_spiral)
101-108 F8.2 --- e_QTspiral ?=-9999.99 Uncertainty on mean spiral
torque associated with the disc thickness
determination (ErrQTspiral)
110-117 F8.2 --- s_QTspiral ?=-9999.99 Internal dispersion of spiral
torque associated to the different
segments (SDQTspiral)
119-126 F8.2 --- QTspiralhalo ?=-9999.99 Mean gravitational torque of the
spiral arms corrected for the dark matter
halo dilution (QTspiralhalo)
128-135 F8.2 --- s_QTspiralhalo ?=-9999.99 Internal dispersion of the
halo-corrected spiral torque associated to
the different segments (SDQTspiral_halo)
137-144 F8.2 --- A2spiral Mean m=2 Fourier amplitude of the spiral
arms (A2_spiral)
146-153 F8.2 --- s_A2spiral ?=-9999.99 Internal dispersion of the
maximum of A2 associated to the segments
(SDA2spiral)
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Note (1): Spiral types as follows:
G = grand-design
M = multi-armed
F = flocculent
Note (2): Quality flag as follows:
1 = good
2 = acceptable
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Acknowledgements:
Simon Diaz-Garcia, Instituto de Astrofisica de Canarias, Spain
References:
Buta et al., 2015ApJS..217...32B 2015ApJS..217...32B
A classical morphological analysis of galaxies in the Spitzer Survey of
Stellar Structure in Galaxies (S4G)
Diaz-Garcia et al., 2016A&A...587A.160D 2016A&A...587A.160D
Characterization of galactic bars from 3.6um S4G imaging
Herrera-Endoqui et al., 2015A&A...582A..86H 2015A&A...582A..86H
Catalogue of the morphological features in the Spitzer Survey of Stellar
Structure in Galaxies (S4G)
Salo et al., 2015ApJS..219....4S 2015ApJS..219....4S
The Spitzer Survey of Stellar Structure in Galaxies (S4G): Multi-component
decomposition strategies and data release
Sheth et al., 2010PASP..122.1397S 2010PASP..122.1397S
The Spitzer Survey of Stellar Structure in Galaxies (S4G)
(End) Simon Diaz-Garcia [IAC, Spain], Patricia Vannier [CDS] 19-Aug-2019