J/A+A/644/A38 Halpha images of stellar bars in galaxies (Diaz-Garcia+, 2020)
Distribution of star formation in galactic bars as seen with Hα and
stacked GALEX UV imaging.
Diaz-Garcia S., Moyano F.D., Comeron S., Knapen J.H., Salo H.,
Bouquin A.Y.K.
<Astron. Astrophys. 644, A38 (2020)>
=2020A&A...644A..38D 2020A&A...644A..38D (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Galaxies, photometry ; Galaxy catalogs ;
Photometry, H-alpha ; Photometry, ultraviolet
Keywords: galaxies: structure - galaxies: star formation -
galaxies: evolution - galaxies: statistics
Abstract:
Stellar bars are known to gradually funnel gas to the central parts of
disk galaxies. It remains a matter of debate why the distribution of
ionized gas along bars and in the circumnuclear regions varies among
galaxies.
Our goal is to investigate the spatial distribution of star formation
(SF) within bars of nearby low-inclination disk galaxies (i<65deg)
from the S4G survey. We aim to link the loci of SF to global
properties of the hosts (morphological type, stellar mass, gas
fraction, and bar-induced gravitational torques), providing
constraints for the conditions that regulate SF in bars.
We use archival GALEX far- and near-UV imaging for 772 barred
galaxies, and for a control sample of 423 non-barred galaxies. We also
assemble a compilation of continuum-subtracted Hα images for 433
barred galaxies, 70 of which we produced from ancillary photometry and
MUSE and CALIFA integral field unit data cubes. We employ two
complementary approaches: i) the analysis of bar (2D) and disk (1D)
stacks built from co-added UV images (oriented and scaled with respect
to the stellar bars and the extent of disks) of hundreds of galaxies
that are binned based on their Hubble stage (T) and bar family; and
ii) the visual classification of the morphology of ionized regions
(traced from Hα and UV data) in individual galaxies into three
main SF classes: A) only circumnuclear SF; B) SF at the bar ends, but
not along the bar; and C) SF along the bar. Barred galaxies with
active and passive inner rings are likewise classified.
Massive, gas-poor, lenticular galaxies typically belong to SF class A;
this is probably related to bar-induced quenching of SF in the disk.
The distribution of SF class B peaks for early- and intermediate-type
spirals; this most likely results from the interplay of gas flow,
shocks, and enhanced shear in massive centrally concentrated galaxies
with large bar amplitudes (the latter is supported by the lack of a
dip in the radial distribution of SF in non-barred galaxies).
Late-type gas-rich galaxies with high gravitational torques are mainly
assigned to SF class C; we argue that this is a consequence of low
shear among the faintest galaxies. In bar stacks of spiral galaxies
the UV emission traces the stellar bars and dominates on their leading
side, as witnessed in simulations. Among early-type spirals the
central UV emission is ∼0.5mag brighter in strongly barred
galaxies, relative to their weakly barred counterparts; this is
probably related to the efficiency of strong bars sweeping the disk
gas and triggering central starbursts. On the contrary, in later types
the UV emission is stronger at all radii in strongly barred galaxies
than in weakly barred and non-barred ones. We also show that the
distributions of SF in inner-ringed galaxies are broadly the same in
barred and non-barred galaxies, including a UV and H{alpha) deficit in
the middle part of the bar; this hints at the effect of resonance
rings trapping gas that is no longer funneled inwards.
Distinct distributions of SF within bars are reported in galaxies of
different morphological types. Star-forming bars are most common among
late-type gas-rich galaxies. Bars are important agents in the
regulation of SF in disks.
Description:
Here we provide the tabulated classifications of the distribution of
star formation (SF) in bars for a sample of 804 non-highly inclined
(i<65deg) disk galaxies (See Diaz-Garcia et al. 2016, Cat.
J/A+A/587/160) from the Spitzer Survey of Stellar Structure in
Galaxies (S4G; Sheth et al. 2010, Cat. J/PASP/122/1397).
We applied a classification method in which the distribution of SF at
the bar region is assigned to a class with the following criteria:
- "A" = SF only in the bar central region.
- "B" = SF at the ends of the bar, but not along the bar;
- "C" = SF along the bar;
- "N" = No flux detection;
- "U" = Uncertain classification.
Subclasses "a" (circumnuclear SF) and "b" (no circumnuclear SF) are
also indicated. Likewise, we indicate whether inner rings are active
("rA") or passive ("rP"), whenever the classification is not uncertain
("rU").
SF is traced from GALEX FUV imaging (available from Bouquin et al.
2018, Cat. J/ApJS/234/18 for 772 galaxies) and from a compilation of
continuum-subtracted Hα images for 433 barred galaxies, 70 of
which we produced from ancillary photometry and MUSE and CALIFA
integral field unit data cubes. These images are made publicly
available here, and the sources are tabulated.
For each galaxy, we also list total stellar masses (from Munoz-Mateos
et al. 2015, Cat. J/ApJS/219/3), atomic gas masses (from HyperLEDA),
revised Hubble stages (from Buta et al. 2015, Cat. J/ApJS/217/32) and
bar torque parameters (from Diaz-Garcia et al. 2016, Cat.
J/A+A/587/160), as these parameters were used in the statistical
analysis of the associated paper (see Sect. 3) and listed in Table A1.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea1.dat 72 804 Fundamental galaxy parameters, classifications
of the distribution of SF in bars, SF activity
in inner rings, and sources of H_alpha imaging
refs.dat 175 54 References
list.dat 149 857 List of fits images
fits/* . 857 Individual fits images
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See also:
J/PASP/122/1397 : Spitzer Survey of Stellar Structure in Galaxies (Sheth+ 2010)
J/ApJS/217/32 : S4G galaxy morphologies in the CVRHS system (Buta+, 2015)
J/A+A/587/A160 : 3.6um S4G Galactic bars characterization (Diaz-Garcia+, 2016)
J/ApJS/234/18 : GALEX/S4G surface brightness profiles. I. (Bouquin+, 2018)
Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Galaxy Galaxy identification
14- 19 F6.2 Msun M* ?=-99.99 Total stellar mass from
Munoz-Mateos et al. (2015, Cat. J/ApJS/219/3)
23- 28 F6.2 Msun MHI ?=-99.99 Total HI gas mass from HyperLEDA
30- 31 I2 --- T Hubble type from Buta et al.
(2015, Cat. J/ApJS/217/32)
35- 40 F6.2 --- Qb ?=-99.99 Bar maximum gravitational torque
from Diaz-Garcia et al.
(2016, Cat. J/A+A/587/160)
42- 43 A2 --- SFclassFUV Bar SF class (A, B, C, N, U), and subclasses
a/b, based on GALEX FUV imaging (1)
45- 46 A2 --- RingSFFUV Determination of active (rA) and passive (rP)
inner rings (including uncertain cases rU),
using GALEX FUV imaging (2)
48- 49 A2 --- SFclassHa Bar SF class based on continuum-subtracted
Hα images (1)
51- 52 A2 --- RingSFHa Inner rings SF activity based on
continuum-subtracted Hα images (2)
55 A1 --- AISFUV [Y/N-] Flagging of GALEX UV images from
All-Sky Imaging Survey (AIS) (Yes/No)
57- 72 A16 --- SourceHa Literature sources of Hα images,
in refs.dat file
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Note (1): Bar SF class as follows:
A = SF only in the bar central region
B = SF at the ends of the bar, but not along the bar
C = SF along the bar
N = No flux detection
U = Uncertain classification
Bar SF Subclass as follows
a = with circumnuclear SF
b = without circumnuclear SF
Note (2): Inner rings SF activity as follows:
rA = active
rP = passive
rU = uncertain case
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Byte-by-byte Description of file: refs.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- Ref Reference code
7- 25 A19 --- BibCode BibCode
27- 51 A25 --- Aut Author's name
53-175 A123 --- Com Comments
--------------------------------------------------------------------------------
Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Galaxy Galaxy name
12- 20 F9.5 deg RAdeg Right Ascension of center (J2000)
21- 29 F9.5 deg DEdeg Declination of center (J2000)
31- 35 F5.3 arcsec/pix scale ? Scale of the image
37- 40 I4 --- Nx Number of pixels along X-axis
42- 45 I4 --- Ny Number of pixels along Y-axis
47 I1 --- Nz ? Number of pixels along Z-axis
49- 71 A23 "datime" Obs.date Observation date
73- 77 I5 Kibyte size Size of FITS file
79-101 A23 --- FileName Name of FITS file, in subdirectory fits
103-149 A47 --- Title Title of the FITS file
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Acknowledgements:
Simon Diaz-Garcia, simondiazgar(at)gmail.com,
Instituto de Astrofisica de Canarias, Spain - Queen's University, Canada
(End) Patricia Vannier [CDS] 03-Nov-2020