J/A+A/632/A15 Star-forming low-mass gal. stellar host (Lumbreras-Calle+, 2019)
The stellar host in star-forming low-mass galaxies: Evidence for two classes.
Lumbreras-Calle A., Mendez-Abreu J., Munoz-Tunon C.
<Astron. Astrophys. 632, A15 (2019)>
=2019A&A...632A..15L 2019A&A...632A..15L (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Galaxy catalogs ; Morphology ; Photometry
Keywords: galaxies: star formation - galaxies: photometry -
galaxies: structure - galaxies: evolution - galaxies: starburst -
galaxies: fundamental parameters
Abstract:
The morphological evolution of star-forming galaxies provides
important clues to understand their physical properties, as well as
the triggering and quenching mechanisms of star formation.
We analyze the morphology of galaxies hosting star-forming events at
low redshift (z<0.36). We aim at connecting morphology and
star-formation properties of low-mass galaxies (median stellar mass
∼108.5M☉) beyond the local Universe.
We use a sample of medium-band selected star-forming galaxies from the
GOODS-North field. H images for the sample are created combining both
spectral energy distribution fits and HST data. Using them, we mask
the star forming regions to obtain an unbiased two-dimensional model
of the light distribution of the host galaxies. For this purpose we
use PHI, a new Bayesian photometric decomposition code. We applied it
independently to 7 HST bands, from the ultraviolet to the
near-infrared, assuming a Sersic surface brightness model.
Star-forming galaxy hosts show low Sersic index (with median n∼0.9),
as well as small sizes (median Re∼1.6kpc), and negligible change of
the parameters with wavelength (except for the axis ratio, which grows
with wavelength in 46% of the sample). Using a clustering algorithm,
we find two different classes of star-forming galaxies: A more compact,
redder, and high-n (class A) and a more extended, bluer and lower-n
one (class B). This separation holds across all seven bands analyzed.
In addition, we find evidence that the first class is more
spheroidal-like (according to the distribution of observed axis
ratios). We compute the color gradients of the host galaxies finding
that 48% of the objects where the analysis could be performed show
negative gradients, and only in 5% they are positive.
The host component of low-mass star-forming galaxies at z<0.36
separates into two different classes, similar to what has been found
for their higher mass counterparts. The results are consistent with an
evolution from class B to class A. Several mechanisms from the
literature, like minor and major mergers, and violent disk
instability, can explain the physical process behind the likely
transition between the classes.
Description:
The data in this table 1 is the output of the photometric
decomposition code PHI (2018MNRAS.479.3076A 2018MNRAS.479.3076A) using a single Sersic
model, applied to the galaxies selected in 2019A&A...621A..52L 2019A&A...621A..52L. This
was performed on HST images from the CANDELS survey
(2011ApJS..197...36K 2011ApJS..197...36K, 2011ApJS..197...35G 2011ApJS..197...35G) using the filters F435W,
F606W, F775W, and F850LP in ACS and F125W, F140W, and F160W in WFC3.
The data in table 2 combines the results obtained in the photometric
decomposition with the results presented in 2019A&A...621A..52L 2019A&A...621A..52L.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 189 95 Physical properties, synthetic magnitudes,
and class to which each galaxy belongs
table1.dat 120 665 Photometric parameters obtained from PHI fitting
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 I8 --- ID SHARDS ID (release DR3 beta)
10- 18 F9.5 deg RAdeg Right Ascension (J2000)
20- 27 F8.5 deg DEdeg Declination (J2000)
29- 34 F6.3 [Msun] logMass Stellar mass of the galaxy
(taken from 2019A&A...621A..52L 2019A&A...621A..52L)
36- 40 F5.3 [Msun] E_logMass Error on logMass (upper value)
42- 46 F5.3 [Msun] e_logMass Error on logMass (lower value)
48- 54 F7.3 [yr-1] logsSFR Specific star formation rate
(SFR/Stellar Mass)
(taken from 2019A&A...621A..52L 2019A&A...621A..52L)
56- 60 F5.3 [yr-1] E_logsSFR Error on logsSFR (upper value)
62- 67 F6.3 [yr-1] e_logsSFR Error on logsSFR (lower value)
69- 74 F6.3 mag Umag Synthetic AB mag of the Sersic model
of the host galaxy in the
Johnson U filter
76- 81 F6.3 mag E_Umag Error on Umag (upper value)
83- 87 F5.3 mag e_Umag Error on Umag (lower value)
89- 94 F6.3 mag Vmag ?=99 Synthetic AB mag of the Sersic
model of the host galaxy in the
Johnson V filter
96-101 F6.3 mag E_Vmag ?=99 Error on Vmag (upper value)
103-108 F6.3 mag e_Vmag ?=99 Error on Vmag (lower value)
110-115 F6.3 mag Jmag Synthetic AB mag of the Sersic model
of the host galaxy in the
Johnson J filter
117-121 F5.3 mag E_Jmag Error on Jmag (upper value)
123-128 F6.3 mag e_Jmag Error on Jmag (lower value)
130-135 F6.3 mag gmag Synthetic AB mag of the Sersic model
of the host galaxy in the
SDSS g filter
137-141 F5.3 mag E_gmag Error on gmag (upper value)
143-147 F5.3 mag e_gmag Error on gmag (lower value)
149-154 F6.3 mag rmag ?=99 Synthetic AB mag of the Sersic
model of the host galaxy in the
SDSS r filter
156-161 F6.3 mag E_rmag ?=99 Error on rmag (upper value)
163-168 F6.3 mag e_rmag ?=99 Error on rmag (lower value)
170-175 F6.3 mag/arcsec+2/kpc g-rgrad g-r color gradient of
the host galaxy model
177-181 F5.3 mag/arcsec+2/kpc E_g-rgrad Error on g-r_grad (upper value)
183-187 F5.3 mag/arcsec+2/kpc e_g-rgrad Error on g-r_grad (lower value)
189 A1 --- Class [A/B] Class of the galaxy (A or B) (1)
--------------------------------------------------------------------------------
Note (1): Class of the galaxy as follows:
A = subsample of galaxies with lower radius, higher n, and redder U-V color
B = subsample of galaxies with larger, bluer, and lower n galaxies
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 I8 --- ID SHARDS ID (release DR3 beta)
10- 15 A6 --- Filter ? HST filter
17- 20 F4.2 --- chi2 ? Chi-squared value of the model fitting
22- 27 F6.3 mag/arcsec+2 mue ? Surface brightness of the Sersic model
at the effective radius
29- 33 F5.3 mag/arcsec+2 E_mue ? Error on mu_e (upper value)
35- 39 F5.3 mag/arcsec+2 e_mue ? Error on mu_e (lower value)
41- 46 F6.3 kpc Re ? Effective radius of the Sersic model
48- 53 F6.3 kpc E_Re ? Error on Re (upper value)
55- 60 F6.3 kpc e_Re ? Error on Re (lower value)
62- 66 F5.3 --- n ? Sersic index of the model
68- 72 F5.3 --- E_n ? Error on n (upper value)
74- 78 F5.3 --- e_n ? Error on n (lower value)
80- 84 F5.3 --- q ? Axis ratio of the Sersic model
86- 90 F5.3 --- E_q ? Error on q (upper value)
92- 96 F5.3 --- e_q ? Error on q (lower value)
98-104 F7.3 deg PA ? Position angle of the Sersic model
106-112 F7.3 deg E_PA ? Error on PA (upper value)
114-120 F7.3 deg e_PA ? Error on PA (lower value)
--------------------------------------------------------------------------------
Acknowledgements:
Alejandro Lumbreras-Calle, alumbrerascalle(at)gmail.com
References:
Lumbreras-Calle et al., Paper I 2019A&A...621A..52L 2019A&A...621A..52L
(End) Patricia Vannier [CDS] 12-Nov-2019