Optical and near-infrared observations of the SPT2349-56 proto-cluster core at <i>z</i> = 4.3

Rotermund, K. M.; Chapman, Scott; Phadke, Kedar A.; Hill, Ryley; Pass, Emily K.; Aravena, M.; Babul, Arif; Béthermin, M.; Canning, Rebecca; Breuck, C. De; Dong, Chenxing; Gonzalez, Anthony H.; Hayward, Christopher C.; Jarugula, Sreevani; Marrone, Daniel P.; Narayanan, Desika; Reuter, C.; Scott, Douglas; Spilker, Justin; Vieira, J. D.; Wang, G; Weiß, A.

doi:10.1093/mnras/stab103

Cited by 21 publications

(49 citation statements)

References 91 publications

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“…The velocity distribution and halo mass of the AzTEC14 group are similar to those of SPT234956, which is known as an extreme overdensity of SMGs at z = 4.3 (Miller et al 2018;Hill et al 2020). Rotermund et al (2021) shows that the stellar mass of the most massive member and total stellar mass of SPT234956 are at least -…”

Section: Size and Mass Evolutionmentioning

confidence: 68%

A Massive Quiescent Galaxy Confirmed in a Protocluster at z = 3.09

Kubo

Umehata

Matsuda

et al. 2021

ApJ

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We report a massive quiescent galaxy at = -+ z 3.0922 spec 0.004 0.008 spectroscopically confirmed at a protocluster in the SSA22 field by detecting the Balmer and Ca II absorption features with the multi-object spectrometer for infrared exploration on the Keck I telescope. This is the most distant quiescent galaxy confirmed in a protocluster to date. We fit the optical to mid-infrared photometry and spectrum simultaneously with spectral energy distribution (SED) models of parametric and nonparametric star formation histories (SFHs). Both models fit the observed SED well and confirm that this object is a massive quiescent galaxy with a stellar mass of = -+  M M log 11.26 0.04 0.03 ( )  and -+ 11.54 0.00 0.03 , and a star formation rate of SFR/M e yr −1 < 0.3 and = -+0.01 0.01 0.03 for parametric and nonparametric models, respectively. The SFH from the former modeling is described as an instantaneous starburst whereas that of the latter modeling is longer-lived, but both models agree with a sudden quenching of the star formation at ∼0.6 Gyr ago. This massive quiescent galaxy is confirmed in an extremely dense group of galaxies predicted as a progenitor of a brightest cluster galaxy formed via multiple mergers in cosmological numerical simulations. We discover three new plausible [O III]λ5007 emitters at 3.0791 z spec 3.0833 serendipitously detected around the target. Two of them just between the target and its nearest massive galaxy are possible evidence of their interactions. They suggest the future great size and stellar mass evolution of this massive quiescent galaxy via mergers.Unified Astronomy Thesaurus concepts: Galaxy evolution (594); Galaxy environments (2029); Giant elliptical galaxies (651); Protoclusters (1297)

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Section: Size and Mass Evolutionmentioning

confidence: 68%

A Massive Quiescent Galaxy Confirmed in a Protocluster at z = 3.09

Kubo

Umehata

Matsuda

et al. 2021

ApJ

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“…The Spitzer Space Telescope was used to observe SPT2349−56 at two wavelengths: 3.6 𝜇m (hereafter 'ch1') and 4.5 𝜇m (hereafter 'ch2'). A total of four observations have now been carried out since 2009, the first two of which were presented in Rotermund et al (2021), where further details can be found. The two subsequent observations used in this paper were carried out in January 2018 (proposal ID 13224, PI S. Chapman) and October 2019 (proposal ID 14216, PI S. Chapman), and uniformly covered ch1 and ch2 with 324 × 100 s dithered exposures (162 exposures per observation for each channel).…”

Section: Iracmentioning

confidence: 99%

“…The Gemini observations used in this paper were presented in Rotermund et al (2021), where details of the imaging, calibration, and data reduction can be found. Here we only provide a brief summary.…”

Section: Geminimentioning

confidence: 99%

“…One such source, SPT2349−56, was discovered in the South Pole Telescope's extragalactic mm-wave point-source catalogue (Vieira et al 2010;Mocanu et al 2013;Everett et al 2020), and is now known to contain dozens of spectroscopically-confirmed galaxies (Miller et al 2018;Hill et al 2020), several LBGs (Rotermund et al 2021), and a number of LAEs, alongside a Lyman-𝛼 blob (Apostolovski et al in prep.). This protocluster lies at a redshift of 4.3 and has an integrated star-formation rate (SFR) of over 10,000 M yr −1 within a diameter of about 500 proper kiloparsecs, well above what is seen in current simulations (Lim et al 2021).…”

mentioning

confidence: 99%

“…Optical observations of SPT2349−56 were initially carried out using the GMOS and FLAMINGOS-2 instruments mounted on the Gemini South telescope, and Spitzer-IRAC was used to observe this protocluster core in the infrared (Rotermund et al 2021). These data were used to obtain rest-frame ultraviolet photometry for nine out of the 14 galaxies originally reported by Miller et al (2018), as well as identifying four LBGs at the same redshift as the structure.…”

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confidence: 99%

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Rapid build-up of the stellar content in the protocluster core SPT2349$-$56 at $z\,{=}\,4.3$

Hill,

Chapman,

Phadke

et al. 2021

Preprint

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The protocluster core SPT2349−56 at 𝑧 = 4.3 is one of the most actively star-forming regions known, yet constraints on the total stellar mass of this system are highly uncertain. We have therefore carried out deep optical and infrared observations of this system, probing rest-frame ultraviolet to infrared wavelengths. Using the positions of the spectroscopically-confirmed protocluster members, we identify counterparts and perform detailed source deblending, allowing us to fit spectral energy distributions in order to estimate stellar masses. We show that the galaxies in SPT2349−56 have stellar masses proportional to their high star-formation rates, consistent with other protocluster galaxies and field submillimetre galaxies (SMGs) around redshift 4. The galaxies in SPT2349−56 have on average lower molecular gas-to-stellar mass fractions and depletion timescales than field SMGs, although with considerable scatter. We construct the stellar-mass function for SPT2349−56 and compare it to the stellar-mass function of 𝑧 = 1 galaxy clusters, finding both to be best described by a Schechter function. We measure rest-frame ultraviolet half-light radii from our HST-F160W imaging, finding that on average the galaxies in our sample are similar in size to typical star-forming galaxies around the same redshift. However, the brightest HST-detected galaxy in our sample, found near the luminosity-weighted centre of the protocluster core, remains unresolved at this wavelength. Hydrodynamical simulations predict that the core galaxies will quickly merge into a brightest cluster galaxy, thus our observations provide a direct view of the early formation mechanisms of this class of object.

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Molecular gas properties of Planck-selected protocluster candidates at z ≃ 1.3–3

Polletta

Dole

Martinache

et al. 2022

A&A

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We report on IRAM 30-m/EMIR observations of 38 Herschel sources chosen as the brightest red submillimeter (submm) sources in 18 Planck-selected fields drawn from the Planck high-z (PHz) sample of protocluster candidates. These fields host overdensities of red Herschel sources, with high star formation rates (∼10 000 M⊙ yr−1), as obtained from the Planck measurements. The goals of these observations are to measure the spectroscopic redshifts of the Herschel sources in the PHz fields, investigate the origin of their bright submm emission, and find evidence of their association with high-z protoclusters. We detected 40 CO lines on a total of 24 bright (S350 μm > 40 mJy) Herschel sources in 14 of the 18 PHz fields. The measured average redshift is ⟨zCO⟩ = 2.25 ± 0.09, spanning a range from 1.32 to 2.75. We measured the redshifts for multiple Herschel sources in projected proximity in eight PHz fields. In half of those fields, we detected between two and three objects at similar redshifts, supporting the idea that the PHz fields contain high-z protoclusters. The detection of sources at different redshifts in the same field demonstrates that foreground and background sources also contribute to the total submm emission. We compared the properties of the molecular gas and of the star formation activity of our sources with samples of normal star-forming galaxies (SFGs), submm galaxies (SMGs), and CO-detected cluster and protocluster galaxies drawn from the literature at similar redshifts. We find that the PHz-IRAM sources are mainly normal SFGs, with only ∼20% undergoing a starburst phase. The PHz-IRAM sources are characterized by star formation rates (⟨SFR⟩ = 1043 ± 157 M⊙ yr−1) and gas masses (⟨Mgas⟩ = (4.0 ± 0.7) × 1011 M⊙) that are, on average, eight and five times higher than those typical of normal SFGs at similar redshifts. Their dust temperatures (⟨Tdust⟩ = 29.2 ± 0.9 K) and depletion timescales (⟨τdep⟩ = 0.47 ± 0.07 Gyr) are instead consistent with those of normal SFGs. The analysis of the CO spectral line energy distribution, available for ten PHz-IRAM sources, peaks at a low quantum rotation number (Jup = 3) in most of the cases, implying low gas excitation. These properties imply that a significant number of PHz-IRAM sources contain extended and cold molecular gas reservoirs at low excitation and that their star formation is driven by secular processes. Multiplicity and moderate gravitational lensing might also play a role in producing the observed properties. Some of these properties are also observed in other CO-detected infrared-luminous protocluster galaxies at z ≃ 1.3 − 3. We find that the protoclusters with the highest level of star formation, drawn from the largest volume simulations available to date, exhibit similar SFRs as compared to the PHz protoclusters; however, they separate out into a higher number of star-forming galaxies. Millimeter and CO observations at higher spatial resolution than those presented here would be necessary to further elucidate the properties of our PHz-IRAM sources and determine which mechanisms drive star formation in infrared-luminous protocluster galaxies.

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Optical and near-infrared observations of the SPT2349-56 proto-cluster core at z = 4.3

Cited by 21 publications

References 91 publications

A Massive Quiescent Galaxy Confirmed in a Protocluster at z = 3.09

A Massive Quiescent Galaxy Confirmed in a Protocluster at z = 3.09

Rapid build-up of the stellar content in the protocluster core SPT2349$-$56 at $z\,{=}\,4.3$

Molecular gas properties of Planck-selected protocluster candidates at z ≃ 1.3–3

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