Exploring the physical properties of lensed star-forming clumps at $2\lesssim z \lesssim6$

Meštrić, U.; Vanzella, E.; Zanella, Anita; Castellano, M.; Calura, F.; Rosati, P.; Bergamini, P.; Mercurio, A.; Meneghetti, M.; Grillo, C.; Caminha, G. B.; Nonino, M.; Merlin, E.; Cupani, G.; Sani, E.

doi:10.48550/arxiv.2202.09377

“…We correct these values for lensing magnification using the lens model of Bergamini et al (2021) The magnification-corrected stellar masses we derived for our galaxies are very low, in the range of 10 5.5 M e  M *  10 10.5 M e . This range of values is in good agreement with what has been found in the literature in other analyses of (smaller) lensed galaxy samples (e.g., Karman et al 2017;Meštrić et al 2022). We show M * as a function of redshift for our sources in Figure 5.…”

Section: Sed-derived Propertiessupporting

confidence: 91%

The Galaxy Starburst/Main-sequence Bimodality over Five Decades in Stellar Mass at z ≈ 3–6.5

Rinaldi

¹

,

Caputi

²

,

Mierlo

³

et al. 2022

ApJ

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We study the relation between stellar mass (M *) and star formation rate (SFR) for star-forming galaxies over approximately five decades in stellar mass ( 5.5 ≲ log 10 ( M * / M ⊙ ) ≲ 10.5 ) at z ≈ 3–6.5. This unprecedented coverage has been possible thanks to the joint analysis of blank non-lensed fields (COSMOS/SMUVS) and cluster lensing fields (Hubble Frontier Fields) that allow us to reach very low stellar masses. Previous works have revealed the existence of a clear bimodality in the SFR–M * plane with a star formation Main Sequence and a starburst cloud at z ≈ 4–5. Here we show that this bimodality extends to all star-forming galaxies and is valid in the whole redshift range z ≈ 3–6.5. We find that starbursts constitute at least ≈20% of all star-forming galaxies with M * ≳ 109 M ⊙ at these redshifts and reach a peak of 40% at z = 4–5. More importantly, 60%–90% of the total SFR budget at these redshifts is contained in starburst galaxies, indicating that the starburst mode of star formation is dominant at high redshifts. Almost all the low stellar mass starbursts with log 10 ( M * / M ⊙ ) ≲ 8.5 have ages comparable to the typical timescales of a starburst event, suggesting that these galaxies are being caught in the process of formation. Interestingly, galaxy formation models fail to predict the starburst/main-sequence bimodality and starbursts overall, suggesting that the starburst phenomenon may be driven by physical processes occurring at smaller scales than those probed by these models.

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“…The combination of Hubble Space Telescope (HST) highresolution imaging with mainly ground-based spectroscopic follow-up of lens galaxy clusters has enabled a broad range of science cases, from the charaterization of the dark matter distribution in cluster cores (Grillo et al 2015;Limousin et al 2016;Cerny et al 2018;Diego et al 2020) to cluster physics (Bonamigo et al 2017(Bonamigo et al , 2018Annunziatella et al 2017;Montes 2022), from cluster galaxy evolution (Annunziatella et al 2016;Mercurio et al 2021) and the study of high-redshift galaxies (Coe et al 2013;Vanzella et al 2021;Meštrić et al 2022) to cosmological analyses (Jullo et al 2010;Caminha et al 2016;Grillo et al 2018). This has motivated numerous imaging programs with HST, such as the Cluster Lensing and Supernova 1324: PI Treu, Treu et al 2022) has recently obtained the deepest ERS data, by pointing at the galaxy cluster Abell 2744.…”

Section: Introductionmentioning

confidence: 99%

New high-precision strong lensing modeling of Abell 2744. Preparing for JWST observations

Bergamini¹,

Acebron²,

Grillo³

et al. 2022

Preprint

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We present a new strong lensing model of the Hubble Frontier Fields galaxy cluster Abell 2744, at z = 0.3072, by exploiting archival Hubble Space Telescope (HST) multi-band imaging and Multi Unit Spectroscopic Explorer (MUSE) follow-up spectroscopy. The lens model considers 90 spectroscopically confirmed multiple images (from 30 background sources), which represents the largest secure sample for this cluster field prior to the recently acquired James Webb Space Telescope observations. The inclusion of the substructures within several extended sources as model constraints allows us to accurately characterize the inner total mass distribution of the cluster and the position of the cluster critical lines. We include the lensing contribution of 225 cluster members, 202 of which are spectroscopically confirmed. We complement this sample with 23 photometric member galaxies which are identified with a convolution neural network methodology with a high degree of purity. We also measure the internal velocity dispersion of 85 cluster galaxies, down to m F160W = 22, to independently estimate the role of the subhalo mass component in the lens model. We investigate the effect of the cluster environment on the total mass reconstruction of the cluster core with two different mass parameterizations. We consider the mass contribution from three external clumps, either based on previous weak-lensing studies, or extended HST imaging of luminous members around the cluster core. In the latter case, the observed positions of the multiple images are better reproduced, with a remarkable accuracy of ∼ 0.37 , a factor of ∼ 2 smaller than previous lens models, that exploited the same HST and MUSE data-sets. As part of this work, we develop and make publicly available a Strong Lensing Online Tool (SLOT) to exploit the predictive power and the full statistical information of this and future models, through a simple graphical interface. We plan to apply our new high-precision strong lensing model to the first analysis of the GLASS-JWST-ERS program, specifically to measure the intrinsic physical properties of high-z galaxies from robust magnification maps.

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“…We, therefore, simultaneously fit for clump size and fluxes, using the method initially developed by Messa et al (2019) and later improved and adapted to take into account lensing models as presented in Messa et al (2022). A similar approach has also been adopted by Meštrić et al (2022).…”

Section: Clumps Modelingmentioning

confidence: 99%

“…The fate and survival of clumps in high-redshift galaxies has been since long debated. On one side, fundamental constraints have been produced by studies of stellar clumps in gravitationally lensed galaxies (Jones et al 2010;Livermore et al 2012Livermore et al , 2015Adamo et al 2013;Johnson et al 2017;Cava et al 2018;Vanzella et al 2017bVanzella et al ,a, 2022bMeštrić et al 2022). Once the magnification, which can reach factors between 2 and >30 at the center of lensing cluster, is accounted for, few to several clumps are detected within these star-forming galaxies with sizes from a few parsecs to hundred parsecs and masses ranging between 10 5 and 10 8 M (e.g., Dessauges-Zavadsky et al 2017;Tamburello et al 2017).…”

Section: Introductionmentioning

confidence: 99%

“…Initial HST studies of clumps in lensed galaxies at redshift 2, find age ranges between a few and tens of Myr up to a few hundreds of Myr (e.g., Adamo et al 2013;Johnson et al 2017;Messa et al 2022;Vanzella et al 2022b). The main limitation has been so far the lack of homogeneous coverage of the UV-optical rest-frame of galaxies at redshift > 2 (e.g., see Meštrić et al 2022, who included ground-based data, although limiting, to improve age and mass estimates of clumps), a key phase for star formation and galaxy evolution.…”

Section: Introductionmentioning

confidence: 99%

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Star formation at the smallest scales; A JWST study of the clump populations in SMACS0723

Claeyssens¹,

Adamo²,

Richard³

et al. 2022

Preprint

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We present the clump populations detected in 18 lensed galaxies at redshifts 1 to 8 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 HST images. We use JWST multiband 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 100s pc and masses ranging from ∼ 10 5 to 10 8 M , overlapping with massive star clusters in the local universe. The ages range from 1 to 100s Myr. We compare the crossing time to the age of the clumps and determine that between 30 and 50 % of the detected clumps are consistent with being gravitationally bound. The lack of Gyr old clumps suggest 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 galaxies at the reionisation era have stellar densities higher than massive 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 color distributions and location within and surrounding their host galaxy that are compatible with recent (100-500 Myr) merger events. 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.

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Exploring the physical properties of lensed star-forming clumps at $2\lesssim z \lesssim6$

Cited by 13 publications

References 81 publications

The Galaxy Starburst/Main-sequence Bimodality over Five Decades in Stellar Mass at z ≈ 3–6.5

The Galaxy Starburst/Main-sequence Bimodality over Five Decades in Stellar Mass at z ≈ 3–6.5

New high-precision strong lensing modeling of Abell 2744. Preparing for JWST observations

Star formation at the smallest scales; A JWST study of the clump populations in SMACS0723

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