J/MNRAS/520/2180 Clumps in galaxies in JWST SMACS0723 field (Claeyssens+, 2023)
Star formation at the smallest scales A JWST study of the clump populations
in SMACS0723.
Claeyssens A., Adamo A., Richard J., Mahler G., Messa M.,
Dessauges-Zavadsky M.
<Mon. Not. R. Astron. Soc. 520, 2180-2203 (2023)>
=2023MNRAS.520.2180C 2023MNRAS.520.2180C (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Galaxies ; Gravitational lensing ; Photometry ;
Infrared ; Positional data ; Redshifts ; Star Forming Region ;
Extinction ; Stars, ages ; Abundances
Keywords: gravitational lensing: strong - galaxies: high-redshift -
galaxies: star clusters: general - galaxies: star formation
Abstract:
We present the clump populations detected in 18 lensed galaxies at
redshifts 1-- 8.5 within the lensing cluster field SMACS0723. The
recent JWST Early Release Observations of this poorly known region of
the sky have revealed numerous point-like sources within and
surrounding their host galaxies, undetected in the shallower Hubble
Space Telescope images. We use JWST multi-and photometry and the
lensing model of this galaxy cluster to estimate the intrinsic sizes
and magnitudes of the stellar clumps. We derive optical restframe
effective radii from <10 to hundreds pc and masses ranging from ∼105
to 109 M☉, overlapping with massive star clusters in the local
universe. Clump ages range from 1 Myr to 1 Gyr. We compare the
crossing time to the age of the clumps and determine that between 45
and 60 per cent of the detected clumps are consistent with being
gravitationally bound. On average, the dearth of Gyr old clumps
suggests that the dissolution time scales are shorter than 1 Gyr. We
see a significant increase in the luminosity (mass) surface density of
the clumps with redshift. Clumps in reionization era galaxies have
stellar densities higher than star clusters in the local universe. We
zoom in into single galaxies at redshift <6 and find for two galaxies,
the Sparkler and the Firework, that their star clusters/clumps show
distinctive colour distributions and location surrounding their host
galaxy that are compatible with being accredited or formed during
merger events. The ages of some of the compact clusters are between 1
and 4 Gyr, e.g. globular cluster precursors formed around 9--12 Gyr
ago. Our study, conducted on a small sample of galaxies, shows the
potential of JWST observations for understanding the conditions under
which star clusters form in rapidly evolving galaxies.
Description:
In this work we use the first imaging observation acquired with the
JWST of the galaxy lensing cluster SMACS J0723.3-7323 (hereafter,
SMACS0723, z = 0.388 in figure of Introduction section ). This region
has been previously observed with HST as part of the RELICS program.
We extended our analysis to the clump populations of galaxies in the
redshift range to 1 from 8. This statistical approach enables us to
look at clump formation and evolution across the most important phases
of galaxy growth and address key questions related to their survival
timescales, as well as the capability of detecting and resolving them
into their star cluster components. The used observations are taken
with Near-Infrared Camera (NIRCam) in F090W, F150W, and F200W short
wavelength (SW) and F277W, F356W, F444W long wavelength (LW) filters,
covering an observed wavelength range of λobs = 0.8-5 µm,
for a total of 12.5 h of integration time. The NIRspec are also used
to redshift determinations. (see observations program ID 2736; PI:
Pontoppidan, Pontoppidan et al. 2022ApJ...936L..14P 2022ApJ...936L..14P).
To detect clumps populations, we adopt a model the galaxy cluster mass
distribution surrounding our targets as a combination of dual
pseudo-isothermal ellipsoids. Using a MCMC method we estimate the mass
model parameters and their uncertainties (i.e more in section 3). In
our case, we focus on studying stellar clumps within galaxies with a
robust redshift measurement and/or a high lensing magnification factor
(i.e. to get high spatial resolution on these images). A significant
fraction of targeted galaxies has been selected from the multiple
systems identified and used to build the lens model. Among them, we
have spectroscopic redshift value measured from muse data and from the
NIRSpec data. The remaining systems have a geometric redshift value
obtained from the lens model optimisation. Each galaxy image has been
visually inspected on NIRCam F150W and F200W filters (reference
filters) to confirm that at least one stellar clump (compact source
surrounded by diffuse extended emission) is clearly detected in both
filters (i.e. section 4).
Of the 21 multiple systems identified, we rejected 12 systems with
poorly constrained redshift estimations from the lens model (with a
1σ uncertainty >0.3) and/or very faint/diffuse (S/N<3)
detections in NIRCam images. In addition to the multiple systems, we
include nine galaxies located outside the multiple images area, but
for which we were able to measure a robust spectroscopic redshift from
the available NIRSpec data. The final sample is, therefore, composed
of 18 galaxies producing 36 images presented in galaxies.dat. Finally as
exposed in sections 5 and 6, we proceeded to clumps identification,
modelling and SED fitting to extract 228 NIRCam photometry values
presented in tableb1.dat and 223 clumps SED physical properties (Reff,
F150WMag, logM*, Age, E(B-V), Z) presented in tableb2.dat.
Objects:
----------------------------------------------------------------------------
RA (2000) DE Designation(s)
----------------------------------------------------------------------------
07 23 13.29 -73 27 25.1 SMACS J0723.3-7327 = 1RXS J072319.7-732735
----------------------------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
galaxies.dat 32 36 Selected galaxies in SMACS J0723.3-7327 cluster
tableb1.dat 126 228 NIRCam photometry of our clumps sample
tableb2.dat 147 223 Main astrometric informations and physical
properties of our the clumps sample
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See also:
J/A+A/666/A80 : Star clusters and fields in the LMC (Narloch+, 2022)
J/ApJ/884/85 : RELICS: Reionization Lensing Cluster Survey (Coe+, 2019)
J/ApJ/686/948 : CO in extragalactic giant molecular clouds (Bolatto+,2008)
J/ApJ/499/112 : HST CFRS and LDSS redshift surveys. I. (Brinchmann+ 1998)
J/ApJS/157/1 : Red-Sequence Cluster Survey (Gladders+, 2005)
J/AJ/140/75 : Antennae galaxies (NGC 4038/4039) revisited
(Whitmore+, 2010)
J/ApJS/107/1 : Morphologies of distant galaxies II (Abraham+ 1996)
J/other/NatAs/2.76 : MACSJ1206.2-08474714 clumps photometry (Cava+, 2018)
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
Byte-by-byte Description of file: galaxies.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Img Galaxy images name identifier (ImageID)
7- 8 I2 h RAh Right ascension of the component (J2000)
10- 11 I2 min RAm Right ascension of the component (J2000)
13- 17 F5.2 s RAs Right ascension of the component (J2000)
19 A1 --- DE- Declination sign of the component (J2000)
20- 21 I2 deg DEd Declination of the component (J2000)
23- 24 I2 arcmin DEm Declination of the component (J2000)
26- 29 F4.1 arcsec DEs Declination of the component (J2000)
31- 32 I2 --- Nclump Number of clumps identified in galaxy image
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Byte-by-byte Description of file: tableb1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- Img Image name identifier (ImageID)
7- 11 A5 --- Clump Clump name identifier (ClumpID)
13- 18 F6.4 --- z Redshift (z)
20- 29 F10.6 deg RAdeg Right ascension (J2000) (RA)
31- 40 F10.6 deg DEdeg Declination (J2000) (DEC)
42- 47 F6.2 --- mu Lensing magnification factor (µ)
49- 54 F6.2 --- E_mu Upper uncertainty of mu
56- 60 F5.2 --- e_mu Lower uncertainty of mu
62- 66 F5.2 mag F090Wmag The JWST NIRCam F090W magnitude in AB system
(F090W)
68- 71 F4.2 mag e_F090Wmag Uncertainty of F090Wmag
73- 77 F5.2 mag F150Wmag The JWST NIRCam F150W magnitude in AB system
(F150W)
79- 82 F4.2 mag e_F150Wmag Uncertainty of F150Wmag
84- 88 F5.2 mag F200Wmag The JWST NIRCam F200W magnitude in AB system
(F200W)
90- 93 F4.2 mag e_F200Wmag Uncertainty of F200Wmag
95- 99 F5.2 mag F277Wmag The JWST NIRCam F277W magnitude in AB system
(F277W)
101-104 F4.2 mag e_F277Wmag Uncertainty of F277Wmag
106-110 F5.2 mag F356Wmag The JWST NIRCam F356W magnitude in AB system
(F356W)
112-115 F4.2 mag e_F356Wmag Uncertainty of F356Wmag
117-121 F5.2 mag F444Wmag The JWST NIRCam F444W magnitude in AB system
(F444W)
123-126 F4.2 mag e_F444Wmag Uncertainty of F444Wmag
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tableb2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- Img Image name identifier (ImageID)
7- 11 A5 --- Clump Clump name identifier (ClumpID)
13- 18 F6.4 --- z Redshift (z)
20- 29 F10.6 deg RAdeg Right ascension (J2000) (RA)
31- 40 F10.6 deg DEdeg Declination (J2000) (DEC)
42- 47 F6.2 --- mu Lensing magnification factor (µ)
50- 55 F6.2 --- E_mu Upper uncertainty of mu
58- 62 F5.2 --- e_mu Lower uncertainty of mu
64 A1 --- l_Reff Upper limit flag on Reff values
66- 68 I3 pc Reff Intrinsic effective radius measured on
NIRCam/F150W with method described in
section 5.3 (Reff)
71- 73 I3 pc E_Reff ? Upper uncertainty of Reff
76- 78 I3 pc e_Reff ? Lower uncertainty of Reff
80- 85 F6.2 mag F150WMag The NIRCam/F150W intrinsic absolute
magnitude in AB system (F150Wabs)
87- 90 F4.2 mag e_F150WMag Uncertainty of F150WMag
92- 94 F3.1 [Msun] logM* ? Derived stellar mass with SED analysis
reference model explained in section 5 and 6
(logM*)
97- 99 F3.1 [Msun] E_logM* ? Upper uncertainty of logM*
102-104 F3.1 [Msun] e_logM* ? Lower uncertainty of logM*
106-109 I4 Myr Age ? Estimated age with SED analysis reference
model explained in section 5 and 6 (Age)
112-115 I4 Myr E_Age ? Upper uncertainty of Age
118-121 I4 Myr e_Age ? Lower uncertainty of Age
123-126 F4.2 mag E(B-V) ? Estimated extinction with SED analysis
reference model explained in section 5 and 6
(EB-V)
129-132 F4.2 mag E_E(B-V) ? Upper uncertainty of E (B-V)
135-138 F4.2 mag e_E(B-V) ? Lower uncertainty of E (B-V)
140 A1 --- n_E(B-V) Note for clumps with an E(B-V) value at
fitted with no extinction
142-147 F6.4 --- Z ? Best estimates of the metallicity fixed to
for SED fits either at 0.02, 0.008, 0.004 or
0.0004 (Metallicity)
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History:
From electronic version of the journal
License: CC-BY-4.0 [see https://spdx.org/licenses/]
(End) Luc Trabelsi [CDS] 12-Mar-2026