J/ApJ/853/108 Clumpy galaxies in CANDELS. II. 0.5≤z<3.0 (Guo+, 2018)
Clumpy galaxies in CANDELS.
II. Physical properties of UV-bright clumps at 0.5≤z<3.
Guo Y., Rafelski M., Bell E.F., Conselice C.J., Dekel A., Faber S.M.,
Giavalisco M., Koekemoer A.M., Koo D.C., Lu Yu, Mandelker N., Primack J.R.,
Ceverino D., de Mello D.F., Ferguson H.C., Hathi N., Kocevski D.,
Lucas R.A., Perez-Gonzalez P.G., Ravindranath S., Soto E., Straughn A.,
Wang W.
<Astrophys. J., 853, 108 (2018)>
=2018ApJ...853..108G 2018ApJ...853..108G
ADC_Keywords: Galaxies, photometry; Photometry, HST; Ultraviolet; Redshifts;
Photometry, UBVRI
Keywords: galaxies: evolution ; galaxies: formation ; galaxies: starburst ;
galaxies: star formation ; galaxies: structure ; ultraviolet: galaxies
Abstract:
Studying giant star-forming clumps in distant galaxies is important to
understand galaxy formation and evolution. At present, however,
observers and theorists have not reached a consensus on whether the
observed "clumps" in distant galaxies are the same phenomenon that is
seen in simulations. In this paper, as a step to establish a benchmark
of direct comparisons between observations and theories, we publish a
sample of clumps constructed to represent the commonly observed
"clumps" in the literature. This sample contains 3193 clumps detected
from 1270 galaxies at 0.5≤z<3.0. The clumps are detected from
rest-frame UV images, as described in our previous paper. Their
physical properties (e.g., rest-frame color, stellar mass (M*), star
formation rate (SFR), age, and dust extinction) are measured by
fitting the spectral energy distribution (SED) to synthetic stellar
population models. We carefully test the procedures of measuring clump
properties, especially the method of subtracting background fluxes
from the diffuse component of galaxies. With our fiducial background
subtraction, we find a radial clump U-V color variation, where clumps
close to galactic centers are redder than those in outskirts. The
slope of the color gradient (clump color as a function of their
galactocentric distance scaled by the semimajor axis of galaxies)
changes with redshift and M* of the host galaxies: at a fixed M*, the
slope becomes steeper toward low redshift, and at a fixed redshift, it
becomes slightly steeper with M*. Based on our SED fitting, this
observed color gradient can be explained by a combination of a
negative age gradient, a negative E(B-V) gradient, and a positive
specific SFR gradient of the clumps. We also find that the color
gradients of clumps are steeper than those of intra-clump regions.
Correspondingly, the radial gradients of the derived physical
properties of clumps are different from those of the diffuse component
or intra-clump regions.
Description:
The galaxies used in this paper are from the CANDELS/GOODS-S sample
presented in Paper I (Guo+, 2015ApJ...800...39G 2015ApJ...800...39G), which is based on
the CANDELS survey (Grogin+ 2011ApJS..197...35G 2011ApJS..197...35G ;
Koekemoer+ 2011ApJS..197...36K 2011ApJS..197...36K).
Clump detection is detailed in Paper I. Briefly, clumps are detected
in rest-frame near-UV (NUV; ∼2800Å), i.e., ACS F435W at 0.5≤z<1.0,
F606W at 1.0≤z<2.0, and F775W at 2.0≤z<3.0. See section 2.2.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 561 22351 Catalog of clumps from 1270 galaxies
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See also:
II/261 : GOODS initial results (Giavalisco+, 2004)
J/AJ/112/359 : Galaxies in the Hubble Deep Field (van den Bergh+ 1996)
J/ApJS/147/1 : Classification of nearby galaxies (Conselice+, 2003)
J/ApJ/612/202 : Catalog of spheroids in UGC 10214 field (Menanteau+, 2004)
J/ApJ/735/L22 : HUDF galaxy properties at z∼2 (Szomoru+, 2011)
J/ApJS/203/24 : Structural param. of galaxies in CANDELS (van der Wel+, 2012)
J/ApJS/207/24 : GOODS-S CANDELS multiwavelength catalog (Guo+, 2013)
J/ApJ/763/73 : Surface density profiles of GOODS-South gal. (Szomoru+, 2013)
J/ApJ/793/101 : CANDELS z∼2 galaxy properties (Trump+, 2014)
J/ApJ/796/60 : ECDFS galaxies photom. redshifts + counterparts (Hsu+, 2014)
J/ApJS/214/24 : 3D-HST+CANDELS catalog (Skelton+, 2014)
J/ApJS/218/33 : Spitzer-CANDELS catalog within 5 deep fields (Ashby+, 2015)
J/ApJS/221/11 : CANDELS visual classifications for GOODS-S (Kartaltepe+, 2015)
J/ApJ/801/97 : GOODS-S & UDS stellar masses from CANDELS (Santini+, 2015)
J/A+A/592/A122 : Starburst galaxies in the COSMOS field (Hinojosa-Goni+, 2016)
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- Gal [18/26834] CANDELS galaxy ID (1)
7- 15 F9.6 deg RAGdeg [52.9/53.3] Galaxy Right Ascension in
decimal degrees (J2000)
17- 26 F10.6 deg DEGdeg [-28/-27.6] Galaxy Declination in
decimal degrees (J2000)
28- 32 F5.3 --- z [0.5/3] Galaxy redshift (2)
34- 39 F6.3 [Msun] logM* [8.8/11.5] log galactic stellar mass (3)
41- 45 F5.3 [Msun] e_logM* [0.06/0.9] Uncertainty in logM*
47- 52 F6.3 [Msun/yr] logSFR [-1.7/3.3] log galactic Star Formation Rate
54- 58 F5.3 [Msun/yr] e_logSFR [0.02/6] Uncertainty in logSFR
60- 66 F7.3 mag GUmag [-23.1/-16.7] Galaxy rest-frame U-band AB
magnitude
68- 74 F7.3 mag GVmag [-24/-18.1] Galaxy rest-frame V-band AB
magnitude
76- 82 F7.3 mag GJmag [-25/-19] Galaxy rest-frame J-band AB
magnitude
84- 88 F5.3 arcsec Rad [0.2/5.4] Galaxy semi-major axis (4)
90- 94 F5.3 arcsec e_Rad [0/0.7] Uncertainty in Rad
96- 97 I2 --- CID [1/18] Clump identifier within Gal (5)
99-107 F9.6 deg RAdeg [52.9/53.3] Clump Right Ascension in
decimal degrees (J2000)
109-118 F10.6 deg DEdeg [-28/-27.6] Clump Declination in
decimal degrees (J2000)
120 A1 --- Det Clump detection band ("v", "b" or "i") (6)
122-126 F5.3 --- fLUV [0.03/1] Ratio of clump to galaxy UV
luminosity (5)
128-135 A8 --- BSC Background subtraction configuration (7)
137-146 F10.6 uJy F435W [-0.6/2.3]?=-99 HST/ACS F435W flux density
148-157 F10.6 uJy e_F435W [0.001/0.05]?=-99 Uncertainty in F435W
159-168 F10.6 uJy F606W [-0.03/3.5]?=-99 HST/ACS F606W flux density
170-179 F10.6 uJy e_F606W [0.0009/0.02]?=-99 Uncertainty in F606W
181-190 F10.6 uJy F775W [-0.07/6.2]?=-99 HST/ACS F775W flux density
192-201 F10.6 uJy e_F775W [0.001/0.04]?=-99 Uncertainty in F775W
203-212 F10.6 uJy F814W [-0.1/5.8]?=-99 HST/ACS F814W flux density
214-223 F10.6 uJy e_F814W [0.004/0.05]?=-99 Uncertainty in F814W
225-234 F10.6 uJy F850LP [-0.1/7.2]?=-99 HST/ACS F850LP flux density
236-245 F10.6 uJy e_F850LP [0.001/0.04]?=-99 Uncertainty in F850LP
247-256 F10.6 uJy F105W [-0.7/8]?=-99 HST/WFC3 F105W flux density
258-267 F10.6 uJy e_F105W [0.001/0.03]?=-99 Uncertainty in F105W
269-278 F10.6 uJy F125W [-0.2/9.6]?=-99 HST/WFC3 F125W flux density
280-289 F10.6 uJy e_F125W [0.001/0.2]?=-99 Uncertainty in F125W
291-300 F10.6 uJy F140W [-0.3/13]?=-99 HST/WFC3 F140W flux density
302-311 F10.6 uJy e_F140W [0.001/0.06]?=-99 Uncertainty in F140W
313-322 F10.6 uJy F160W [-0.6/15]?=-99 HST/WFC3 F160W flux density
324-333 F10.6 uJy e_F160W [0.001/0.05]?=-99 Uncertainty in F160W
335-339 F5.3 --- Dist [0.3/7.5] Galactocentric distance;
normalized by galaxy MajAxis
341-347 F7.3 --- zphot [0.2/4]?=-99 Clump photometric redshift;
see Section 3.2
349-351 I3 --- q_zphot [-99/1] Flag on zphot (1=bad or 0=good)
353-358 F6.3 [Msun] CMass [5.4/11] log clump stellar mass;
Section 4.1 (8)
360-365 F6.3 [Msun] b_CMass [5/11] CMass 16% uncertainty boundary
367-372 F6.3 [Msun] B_CMass [5.6/11.2] CMass 84% uncertainty boundary
374-380 F7.3 [Msun/yr] CSFR [-11/3] log clump Star Formation Rate (8)
382-388 F7.3 [Msun/yr] b_CSFR [-20.5/2.6] CSFR 16% uncertainty boundary
390-395 F6.3 [Msun/yr] B_CSFR [-3/3] CSFR 84% uncertainty boundary
397-401 F5.3 mag E(B-V) [0/1] Clump color excess in (B-V) (8)
403-407 F5.3 mag b_E(B-V) [0/1] 16% uncertainty boundary in E(B-V)
409-413 F5.3 mag B_E(B-V) [0/1] 84% uncertainty boundary in E(B-V)
415-420 F6.3 [Gyr] logAge [-2/1] log clump age (8)
422-427 F6.3 [Gyr] b_logAge [-2/1] 16% uncertainty boundary in logAge
429-434 F6.3 [Gyr] B_logAge [-2/1] 84% uncertainty boundary in logAge
436-441 F6.3 [Gyr] logtau [-1/2] log τ-model value (8)
443-448 F6.3 [Gyr] b_logtau [-1/2] 16% uncertainty boundary in logtau
450-455 F6.3 [Gyr] B_logtau [-1/2] 84% uncertainty boundary in logtau
457-463 F7.3 mag CUmag [-22/-10.9]?=-99 Clump rest-frame
U-band AB magnitude
465-471 F7.3 mag e_CUmag [0.001/10]?=-99 Uncertainty in CUmag
473-479 F7.3 mag CBmag [-22.1/-11.4]?=-99 Clump rest-frame
B-band AB magnitude
481-487 F7.3 mag e_CBmag [0.001/9.6]?=-99 Uncertainty in CBmag
489-495 F7.3 mag CVmag [-22.1/-10.9]?=-99 Clump rest-frame
V-band AB magnitude
497-503 F7.3 mag e_CVmag [0.001/10]?=-99 Uncertainty in CVmag
505-516 E12.5 [Msun/yr] logUVSFR [-1.6/4]?=-99 log UV Star Formation Rate;
see Section 4.4
518-529 E12.5 [Msun/yr] e_logUVSFR [0.006/5e+25]?=-99 Uncertainty in logUVSFR
531-542 E12.5 mag UVE(B-V) [-6.8e-07/1.4]?=-99 UV derived E(B-V)
544-555 E12.5 mag e_UVE(B-V) [0/3]?=-99 Uncertainty in UVE(B-V)
557 I1 --- VRFlag [0/1] Very red flag (1=very red U-V;
0=blue)
559 I1 --- BMFlag [0/1] Bad mass flag (1=bad; 0=ok)
561 I1 --- EFlag [0/1] Extreme SFR flag (9)
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Note (1): Guo et al. (2013, J/ApJS/207/24).
Note (2): Dahlen et al. (2013ApJ...775...93D 2013ApJ...775...93D).
Note (3): Mobasher et al. (2015ApJ...808..101M 2015ApJ...808..101M).
Santini et al. (2015, J/ApJ/801/97).
Note (4): van der Wel et al. (2014ApJ...788...28V 2014ApJ...788...28V).
Note (5): Guo et al. (2015ApJ...800...39G 2015ApJ...800...39G).
Note (6): Guo et al. (2015ApJ...800...39G 2015ApJ...800...39G) or Section 2.2.
Note (7): We try different methods of background subtraction, see Section 3.1.
Table 2 gives the difference between subtractions:
-----------------------------------------------------------------------------
Method Clump Mask Background Median Photo-z Photo-z Comment
Size Aperture Relative σ Outlier
F160W Flux
(arcsec) (arcsec) (normalized)
-----------------------------------------------------------------------------
bgsub_v6 0.18 0.18-0.30 0.67 0.114 6.99% Very aggressive
subtraction
bgsub_v5 0.18 0.24-0.36 0.86 0.088 6.86% ---
bgsub_v4 0.24 0.24-0.36 1.00 0.074 6.66% Fiducial
subtraction
bgsub_v3 0.24 0.24-0.42 1.08 0.072 6.59% ---
bgsub_v2 0.24 0.30-0.42 1.14 0.073 6.55% ---
bgsub_v1 0.24 0.36-0.48 1.25 0.063 6.44% Very conservative
subtraction
bgsub_v0 --- --- 2.17 0.042 5.76% No background
subtraction
-----------------------------------------------------------------------------
Note (8): Median of 100 MC sampling.
Note (9): Extreme SFR flag as follows:
1 = log(SFR)>3 or log(SFR)<-2, indicating that the SED fitting chooses an
extreme solution, possibly due to an error in either photometry or
SED fitting;
0 = other.
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History:
From electronic version of the journal
References:
Guo et al. Paper I. 2015ApJ...800...39G 2015ApJ...800...39G
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 30-Oct-2018