Abstract
Massive galaxy clusters have been found that date to times as early as three billion years after the Big Bang, containing stars that formed at even earlier epochs1,2,3. The high-redshift progenitors of these galaxy clusters—termed ‘protoclusters’—can be identified in cosmological simulations that have the highest overdensities (greater-than-average densities) of dark matter4,5,6. Protoclusters are expected to contain extremely massive galaxies that can be observed as luminous starbursts7. However, recent detections of possible protoclusters hosting such starbursts8,9,10,11 do not support the kind of rapid cluster-core formation expected from simulations12: the structures observed contain only a handful of starbursting galaxies spread throughout a broad region, with poor evidence for eventual collapse into a protocluster. Here we report observations of carbon monoxide and ionized carbon emission from the source SPT2349-56. We find that this source consists of at least 14 gas-rich galaxies, all lying at redshifts of 4.31. We demonstrate that each of these galaxies is forming stars between 50 and 1,000 times more quickly than our own Milky Way, and that all are located within a projected region that is only around 130 kiloparsecs in diameter. This galaxy surface density is more than ten times the average blank-field value (integrated over all redshifts), and more than 1,000 times the average field volume density. The velocity dispersion (approximately 410 kilometres per second) of these galaxies and the enormous gas and star-formation densities suggest that this system represents the core of a cluster of galaxies that was already at an advanced stage of formation when the Universe was only 1.4 billion years old. A comparison with other known protoclusters at high redshifts shows that SPT2349-56 could be building one of the most massive structures in the Universe today.
This is a preview of subscription content, access via your institution
Access options
Access Nature and 54 other Nature Portfolio journals
Get Nature+, our best-value online-access subscription
$29.99 / 30 days
cancel any time
Subscribe to this journal
Receive 51 print issues and online access
$199.00 per year
only $3.90 per issue
Buy this article
- Purchase on Springer Link
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
Change history
21 June 2018
Change history: In this Letter, the Acknowledgements section should have included the following sentence: “The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.”. This omission has been corrected online.
References
Wang, T. et al. Discovery of a galaxy cluster with a violently starbursting core at z = 2.506. Astrophys. J. 828, 56 (2016).
Mantz, A. B. et al. The XXL Survey: XVII. X-ray and Sunyaev-Zel’dovich properties of the redshift 2.0 galaxy cluster XLSSC 122. Astron. Astrophys. https://doi.org/10.1051/0004-6361/201630096 (2017).
Stanford, S. A. et al. IDCS J1426.5+3508: discovery of a massive, infrared-selected galaxy cluster at z = 1.75. Astrophys. J. 753, 164 (2012).
Springel, V. et al. Simulating the joint evolution of quasars, galaxies and their large-scale distribution. Nature 435, 629–636 (2005).
Overzier, R. A. et al. ΛCDM predictions for galaxy protoclusters—I. The relation between galaxies, protoclusters and quasars at z ~ 6. Mon. Not. R. Astron. Soc. 394, 577–594 (2009).
Chiang, Y.-K., Overzier, R. A., Gebhardt, K. & Henriques, B. Galaxy protoclusters as drivers of cosmic star formation history in the first 2 Gyr. Astrophys. J. Lett. 844, L23 (2017).
Miley, G. & De Breuck, C. Distant radio galaxies and their environments. Astron. Astrophys. Rev. 15, 67–144 (2008).
Casey, C. M. et al. A massive, distant proto-cluster at z = 2.47 caught in a phase of rapid formation? Astrophys. J. Lett. 808, L33 (2015).
Chapman, S. C. et al. Do submillimeter galaxies really trace the most massive dark-matter halos? Discovery of a high-z cluster in a highly active phase of evolution. Astrophys. J. 691, 560–568 (2009).
Tamura, Y. et al. Spatial correlation between submillimetre and Lyman-α galaxies in the SSA22 protocluster. Nature 459, 61–63 (2009).
Ma, J. et al. Stellar masses and star formation rates of lensed, dusty, star-forming galaxies from the SPT survey. Astrophys. J. 812, 88 (2015).
Chiang, Y.-K., Overzier, R. & Gebhardt, K. Ancient light from young cosmic cities: physical and observational sgnatures of galaxy proto-clusters. Astrophys. J. 779, 127 (2013).
Vieira, J. D. et al. Extragalactic millimeter-wave sources in the South Pole Telescope survey data: source counts, catalog, and statistics for an 87 square-degree field. Astrophys. J. 719, 763–783 (2010).
Mocanu, L. M. et al. Extragalactic millimeter-wave point source catalog, number counts and statistics from 771 square degrees of the SPT-SZ survey. Astrophys. J. 779, 61 (2013).
Vieira, J. D. et al. Dusty starburst galaxies in the early Universe as revealed by gravitational lensing. Nature 495, 344–347 (2013).
Spilker, J. et al. ALMA imaging and gravitational lens models of South Pole Telescope-selected dusty, star-forming galaxies at high redshifts. Astrophys. J. 826, 112 (2016).
Strandet, M. L. et al. The redshift distribution of dusty star forming galaxies from the SPT survey. Astrophys. J. 822, 80 (2016).
Beers, T. C. et al. Measures of location and scale for velocities in clusters of galaxies—a robust approach. Astron. J. 100, 32 (1990).
Evrard, A. E. et al. Virial scaling of massive dark matter halos: why clusters prefer a high normalization cosmology. Astrophys. J. 672, 122–137 (2008).
Cole, S., Helly, J., Frenk, C. S. & Parkinson, H. The statistical properties of Lambda cold dark matter halo formation. Mon. Not. R. Astron. Soc. 383, 546–556 (2008).
Ono, Y., Ouchi, M., Kurono, Y. & Momose, R. Faint submillimeter galaxies revealed by multifield deep ALMA observation: number counts, spatial clustering, and a dark submillimeter line emitter. Astrophys. J. 795, 5 (2014).
Simpson, J. M. et al. An ALMA survey of submillimeter galaxies in the extended Chandra deep field south: the redshift distribution and evolution of submillimeter galaxies. Astrophys. J. 788, 125 (2014).
Oteo, I. et al. An extreme proto-cluster of luminous dusty starbursts in the early Universe. Preprint at https://export.arxiv.org/pdf/1709.02809 (2017).
Granato, G. L. et al. The early phases of galaxy clusters formation in IR: coupling hydrodynamical simulations with GRASIL-3D. Mon. Not. R. Astron. Soc. 450, 1320–1332 (2015).
Renzini, A. Stellar population diagnostics of elliptical galaxy formation. Annu. Rev. Astron. Astrophys. 44, 141–192 (2006).
Oñorbe, J. et al. How to zoom: bias, contamination and Lagrange volumes in multimass cosmological simulations. Mon. Not. R. Astron. Soc. 437, 1894–1908 (2013).
Carlstrom, J. E. et al. The 10 meter South Pole Telescope. Publ. Astron. Soc. Pacific 123, 568 (2011).
Ashby, M. L. N. et al. The Spitzer South Pole Telescope deep field: survey dDesign and infrared array camera catalogs. Astrophys. J. Suppl. Ser. 209, 22 (2013).
Planck Collaboration. Planck 2013 results. XXII. Constraints on inflation. Astron. Astrophys. 571, A22 (2014).
Weiß, A. et al. ALMA redshifts of millimeter-selected galaxies from the SPT survey: the redshift distribution of dusty star-forming galaxies. Astrophys. J. 767, 88 (2013).
Siringo, G. et al. The Large APEX BOlometer CAmera LABOCA. Astron. Astrophys. 497, 945–962 (2009).
Weiß, A. et al. LABOCA observations of nearby, active galaxies. Astron. Astrophys. 490, 77–86 (2008).
Aravena, M. et al. The ALMA spectroscopic survey in the Hubble ultra deep field: search for CII line and dust emission in 6 < z < 8 galaxies. Astrophys. J. 833, 71 (2016).
Williams, J. P. et al. Clumpfind: determining structure in molecular clouds (Astrophysics Source Code Library ascl:1107.014, 2011).
Wilson, W. E. et al. The Australia Telescope Compact Array broad-band backend: description and first results. Mon. Not. R. Astron. Soc. 416, 832–856 (2011).
Sault, R. J., Teuben, P. J. & Wright, M. C. H. A retrospective view of Miriad. Astron. Data Analysis Software Systems IV 77, 433 (1995).
Mcmullin, J. P., Waters, B., Schiebel, D., Young, W. & Golap, K. CASA architecture and applications. Astron. Data Analysis Software Systems XVI 376, 127 (2007).
Solomon, P. M. et al. The molecular interstellar medium in ultraluminous infrared galaxies. Astrophys. J. 478, 144–161 (1997).
Fazio, G. G. et al. The Infrared Array Camera (IRAC) for the Spitzer Space Telescope. Astrophys. J. Suppl. Ser. 154, 10–17 (2004).
Werner, M. W. et al. The Spitzer Space Telescope Mission. Astrophys. J. Suppl. Ser. 154, 1–9 (2004).
Béthermin, M., Dole, H., Cousin, M. & Bavouzet, N. Submillimeter number counts at 250, 350 and 500 microns in BLAST data. Astron. Astrophys. 516, A43 (2010).
Barger, A. J. et al. Is there a maximum star formation rate in high-redshift galaxies? Astrophys. J. 784, 9 (2014).
Safarzadeh, M., Hayward, C. C., Ferguson, H. C. & Somerville, R. S. What shapes the far-infrared spectral energy distributions of galaxies? Astrophys. J. 818, 62 (2016).
Bothwell, M. S. et al. A survey of molecular gas in luminous sub-millimetre galaxies. Mon. Not. R. Astron. Soc. 429, 3047–3067 (2013).
Burgarella, D. et al. Star formation and dust attenuation properties in galaxies from a statistical ultraviolet-to-far-infrared analysis. Mon. Not. R. Astron. Soc. 360, 1413–1425 (2005).
Noll, S. et al. Analysis of galaxy spectral energy distributions from far-UV to far-IR with CIGALE: studying a SINGS test sample. Astron. Astrophys. 507, 1793–1813 (2009).
Bruzual, G. & Charlot, S. Stellar population synthesis at the resolution of 2003. Mon. Not. R. Astron. Soc. 344, 1000–1028 (2003).
Chabrier, G. The galactic disk mass function: reconciliation of the Hubble Space Telescope and nearby determinations. Astrophys. J. 586, L133–L136 (2003).
Casey, C. M. The ubiquity of coeval starbursts in massive galaxy cluster progenitors. Astrophys. J. 824, 36 (2016).
Chapman, S. C., Blain, A. W., Smail, I. & Ivison, R. J. A redshift survey of the submillimeter galaxy population. Astrophys. J. 622, 772–796 (2005).
Blain, A. W., Chapman, S. C., Smail, I. & Ivison, R. Clustering of submillimetre-selected galaxies. Astrophys. J. 611, 725–731 (2004).
Kurk, J. D. et al. A search for clusters at high redshift. I. Candidate Lyalpha emitters near 1138-262 at z = 2.2. Astron. Astrophys. 358, L1–L4 (2000).
Kuiper, E. et al. A SINFONI view of flies in the Spiderweb: a galaxy cluster in the making. Mon. Not. R. Astron. Soc. 415, 2245–2256 (2011).
Dannerbauer, H. et al. An excess of dusty starbursts related to the Spiderweb galaxy. Astron. Astrophys. 570, A55 (2014).
Steidel, C. et al. A large structure of galaxies at redshift z ∼ 3 and its cosmological implications. Astrophys. J. 492, 428–438 (1998).
Hayashino, T. et al. Large-scale structure of emission-line galaxies at z = 3.1. Astron. J. 128, 2073–2079 (2004).
Chapman, S. C. et al. Submillimeter imaging of a protocluster region at z = 3.09. Astrophys. J. 548, L17–L21 (2001).
Geach, J. E. et al. A submillimetre survey of Lyman α haloes in the SA 22 protocluster at z = 3.1. Mon. Not. R. Astron. Soc. 363, 1398–1408 (2005).
Umehata, H. et al. ALMA deep field in SSA22: a concentration of dusty starbursts in a z = 3.09 protocluster core. Astrophys. J. Lett. 815, L8 (2015).
Hung, C.-L. et al. Large scale structure around a z = 2.1 cluster. Astrophys. J. 826, 130 (2016).
Daddi, E. et al. Two bright submillimeter galaxies in a z = 4.05 protocluster in GOODS-North, and accurate radio-infrared photometric redshifts. Astrophys. J. 694, 1517–1538 (2009).
Daddi, E. et al. A CO emission line from the optical and near-IR undetected submillimeter galaxy GN10. Astrophys. J. 695, L176–L180 (2009).
Walter, F. et al. The intense starburst HDF 850.1 in a galaxy overdensity at z ∼ 5.2 in the Hubble Deep Field. Nature 486, 233–236 (2012).
Lewis, A. J. R. et al. Ultra-red galaxies signpost candidate proto-clusters at high redshift. Preprint at https://arxiv.org/pdf/1711.08803v1.pdf (2017).
Noirot, G. et al. HST grism confirmation of two z ∼ 2 structures from the clusters around radio-loud AGN (CARLA) survey. Astrophys. J. 830, 90 (2016).
Ivison, R. J. et al. Herschel-ATLAS: a binary HyLIRG pinpointing a cluster of starbursting proto-ellipticals. Astrophys. J. 772, 137 (2013).
Fu, H. et al. The rapid assembly of an elliptical galaxy of 400 billion solar masses at a redshift of 2.3. Nature 498, 338–341 (2013).
Chapman, S. C. et al. A millimetre-wave redshift search for the unlensed HyLIRG, HS1700.850.1. Mon. Not. R. Astron. Soc. 453, 951–959 (2015).
Miller, T. B., Hayward, C. C., Chapman, S. C. & Behroozi, P. S. The bias of the submillimetre galaxy population: SMGs are poor tracers of the most-massive structures in the z ∼ 2 Universe. Mon. Not. R. Astron. Soc. 452, 878–883 (2015).
Trainor, R. F. & Steidel, C. C. The halo masses and galaxy environments of hyperluminous QSO’s at z ∼ 2.7 in the Keck Baryonic Structure Survey. Astrophys. J. 752, 39 (2012).
Rosati, P. et al. Multi-wavelength study of XMMU J2235.3-2557: the most massive galaxy cluster at z > 1. Astron. Astrophys. 508, 583–591 (2009).
Brodwin, M. et al. IDCS J1426.5+3508: the most massive galaxy cluster at z > 1.5. Astrophys. J. 817, 122 (2016).
Andreon, S. et al. JKCS 041: a Coma cluster progenitor at z = 1.803. Astron. Astrophys. 565, A120 (2014).
Gobat, R. et al. A mature cluster with X-ray emission at z = 2.07. Astron. Astrophys. 526, A133 (2011).
Gobat, R. et al. WFC3 GRISM confirmation of the distant cluster Cl J1449+0856 at < z > = 2.00: quiescent and star-forming galaxy populations. Astrophys. J. 776, 9 (2013).
Bocquet, S. et al. Mass calibration and cosmological analysis of the SPT-SZ galaxy cluster sample using velocity dispersion and X-ray measurements. Astrophys. J. 799, 214 (2014).
Mandelker, N., van Dokkum, P. G., Brodie, J. P., van den Bosch, F. C. & Ceverino, D. Cold filamentary accretion and the formation of metal poor globular clusters and halo stars. Preprint at https://arxiv.org/abs/1711.09108v1 (2017).
Cautun, M., van de Weygaert, R., Jones, B. J. T. & Frenk, C. S. Evolution of the cosmic web. Mon. Not. R. Astron. Soc. 441, 2923–2973 (2014).
Bower, R. G. et al. Breaking the hierarchy of galaxy formation. Mon. Not. R. Astron. Soc. 370, 645–655 (2006).
Hopkins, P. F., Hernquist, L., Cox, T. J. & Kereš, D. A cosmological framework for the co-evolution of quasars, supermassive black holes, and elliptical galaxies. I. Galaxy mergers and quasar activity. Astrophy. J. Suppl. Ser. 175, 356–389 (2008).
Hayward, C. C. et al. Spatially unassociated galaxies contribute significantly to the blended submillimetre galaxy population: predictions for follow-up observations of ALMA sources. Mon. Not. R. Astron. Soc. 434, 2572–2581 (2013).
Prada, F., Klypin, A. A., Cuesta, A. J., Betancort-Rijo, J. E. & Primack, J. Halo concentrations in the standard Λ cold dark matter cosmology. Mon. Not. R. Astron. Soc. 423, 3018–3030 (2012).
Behroozi, P. S., Wechsler, R. H. & Wu, H.-Y. The rockstar phase-space temporal halo finder and the velocity offsets of cluster cores. Astrophys. J. 762, 109 (2011).
Behroozi, P. S., Wechsler, R. H. & Conroy, C. The average star formation histories of galaxies in dark matter halos from z = 0−8. Astrophys. J. 770, 57 (2013).
Sargent, M. T. et al. The contribution of starbursts and normal galaxies to infrared luminosity functions at z < 2. Astrophys. J. 747, L31 (2012).
Hayward, C. C. et al. Submillimetre galaxies in a hierarchical universe: number counts, redshift distribution and implications for the IMF. Mon. Not. R. Astron. Soc. 428, 2529–2547 (2013).
Hayward, C. C. et al. What does a submillimeter galaxy selection actually select? The dependence of submillimeter flux density on star formation rate and dust mass. Astrophys. J. 743, 159 (2011).
Acknowledgements
This paper makes use of the following ALMA data (http://www.almaobservatory.org/en/home/): ADS/JAO.ALMA#2016.1.00236.T and ADS/JAO.ALMA#2015.1.01543.T. ALMA is a partnership of the European Southern Observatory (ESO, representing its member states), the National Science Foundation (NSF, USA) and the National Institute of Natural Sciences (NINS, Japan), together with the National Research Council (NRC, Canada) and the National Security Council (NSC) and the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA, Taiwan), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, Associated Universities Inc. (AUI)/National Radio Astronomy Observatory (NRAO) and the National Astronomical Observatory of Japan (NAOJ). This work is also based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. The SPT is supported by the NSF through grant PLR-1248097, with partial support through grant PHY-1125897, the Kavli Foundation and the Gordon and Betty Moore Foundation grant GBMF 947. This publication is based on data acquired with the Atacama Pathfinder Experiment (APEX) under programmes E-299.A-5045A-2017 and ID M-091.F-0031-2013. APEX is a collaboration between the Max-Planck-Institut für Radioastronomie, the ESO, and the Onsala Space Observatory. Supporting observations were obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the NSF (USA), the NRC (Canada), Comisión Nacional de Investigación Científica y Tecnológica (CONICYT, Chile), Ministerio de Ciencia, Tecnologa e Innovacion Productiva (Argentina), and Ministerio da Ciencia, Tecnologia e Inovacao (Brazil). The Australia Telescope Compact Array (ATCA) is part of the Australia Telescope National Facility which is funded by the Australian Government for operation as a National Facility managed by the Commonwealth Scientific and Industrial Research Organisation (CSIRO). D.P.M., J.S.S., J.D.V., K.C.L. and J.S. acknowledge support from the US NSF under grant AST-1312950. S.C.C., T.B.M. and A.B. acknowledge support from the National Sciences and Engineering Research Council (NSERC). S.C.C. and T.B.M. acknowledge the Canada Foundation for Innovation (CFI) and the Killam trust. M.A. acknowledges partial support from the Fondo Nacional de Desarrollo Científica y Tecnológico (FONDECYT, Chile) through grant 114009. The Flatiron Institute is supported by the Simons Foundation. J.D.V. acknowledges support from an A.P. Sloan Foundation Fellowship. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
Reviewer information
Nature thanks P. Capak and C. Papovich for their contribution to the peer review of this work.
Author information
Authors and Affiliations
Contributions
T.B.M. led the data analysis and assembled the paper. S.C.C. designed the study, proposed the ALMA observations, re-imaged the data, and analysed the data products. C.C.H. developed the theoretical model and advised on the literature comparison. M.A. led the ATCA follow-up and the blind emission-line studies. A.W. procured and analysed the deep LABOCA imaging. M.Br. provided the cluster mass and evolution context and discussion. J.S.S. reimaged the calibrated data. K.A.P. performed the spectral energy distribution (SED) fitting. T.B.M, S.C.C., M.A., K.A.P. and A.W. made the figures. S.C.C., T.B.M., M.A., C.C.H., J.D.V. and A.W. wrote the manuscript. All authors discussed the results and provided comments on the paper. The authors are ordered alphabetically after A.W.
Corresponding author
Ethics declarations
Competing interests
The authors declare no competing interests.
Additional information
Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Extended data figures and tables
Extended Data Fig. 1 IRAC observations of SPT2349-56.
Circles show the locations of the 14 sources detected in ALMA band 7 (see Methods). Nine of the 14 ALMA sources are detected in the IRAC bands with at least 3σ confidence, including the two faintest [C ii] sources from the blind line survey.
Extended Data Fig. 2 Herschel–SPIRE image.
An RGB scale is used to represent sources selected at wavelengths of 500 μm (red), 350 μm (green) and 250 μm (blue), with the red SPT2349-56 extended complex clearly visible in a relative void in the foreground z ≈ 1 cosmic infrared background (blue to green coloured galaxies).
Extended Data Fig. 3 Wide-field 870-μm image and photometry.
A wide-field LABOCA image (21″ beam size; white circle) of SPT2349-56. The image r.m.s. noise is 1.3 mJy at the centre of region shown to the right, increasing to 2 mJy at the edges of this region. The total flux density recovered is 110.0 ± 9.5 mJy. Subregions are drawn with black outlines, showing three different regions and their recovered flux densities. Grey contours start at 3σ and increase in steps of 3σ. SPT 1.4-mm contours are also shown (blue), revealing that even with the 1′ beam of SPT, SPT2349-56 is resolved. One additional submillimetre source is detected at > 5σ in the LABOCA image to the east (left) of the primary source, though Herschel–SPIRE photometry indicates that it is unlikely to be at z ≈4.
Extended Data Fig. 4 CO(2–1) observations of SPT2349-56.
a, The colour map and red contours trace the CO(2–1) line integrated over the central 830 km s−1, with the contours spaced by 2σ, starting at 2σ. The grey contours show the 1.1-mm ALMA continuum detections. N, north; W, west; C, centre. Black circles show the location of the 14 [C ii]/continuum sources identified with ALMA. b, One-dimensional spectra extracted at the positions indicated with blue crosses in panel a.
Extended Data Fig. 5 SPIRE RGB image and source colours in the field surrounding SPT2349-56.
a, A deep SPIRE false-colour image is shown with LABOCA contours overlaid. Locations of the 250-μm peaks used for analysis are marked with crosses (the faintest are not visible because of the contrast adopted in the image). The turquoise, blue, green and white crosses relate to the turquoise, blue, green and black lines used in panels b and c. b, c, Colour–colour (b) and colour–flux (c) diagrams for the 250-μm sources. Error bars represent 1σ standard deviation. The colour–colour diagram shows sources with SNR(250 μm) ratios of more than 3 and is dominated by the z ≈ 1 cosmic infrared background in the foreground of SPT2349-56 (sources with colours ranging from blue to green). The colour–flux diagram applies an additional cut for SNR(500 μm) ratios of more than 3. The colour–colour and colour–flux diagrams show that one of three peaks associated with SPT2349-56 is probably a lower-redshift interloper (green symbol), but also that there are five additional sources (blue symbols) in the surrounding region with colours (S500μm > S350μm > S250μm) that are suggestive of z = 4.3.
Extended Data Fig. 6 Spectral energy distribution of SPT2349-56.
The SED of the extended SPT2349-56 source is shown, including the summed deconvolved Herschel–SPIRE flux densities, the total 870-μm LABOCA flux density, and the summed IRAC flux densities. Error bars represent 1σ measurement errors. We do not include the SPT 1.4-mm, 2.0-mm and 3.0-mm points because the source is elongated and flux measurements are difficult with the filtering used to make the map. Fitting the SED yields an infrared luminosity of (8.0 ± 1.0) × 1013Lʘ.
Extended Data Fig. 7 Geometry and dynamics of the SPT2349-56 system.
a, Velocity offsets of the 14 sources versus projected (physical) distance, compared with the escape velocity of a 1.16 × 1013Mʘ NFW halo (virial radius ≈ 200 kpc; concentration = 5). The grey shaded region shows our estimated halo-mass uncertainty; also shown is the escape velocity assuming a point mass halo of this same mass. Centres for the distribution of the 14 galaxies are shown at the mean of the distribution, and centred on the ‘B’ galaxy. All galaxies are bound for all but the lowest range of NFW halo masses. b, The cumulative velocity distribution of the SPT2349-56 galaxies, compared with a Gaussian distribution with our estimated dispersion (σ, 408 km s−1), is at least consistent with expectations for a relatively bound system. c, The physical distribution of the SPT2349-56 galaxies (blue squares), assuming that their redshifts are due to cosmic expansion rather than peculiar motions. This gives an extreme (but unlikely) possibility that the SPT2349-56 galaxies are stretched out along a filament compared with their 130-kpc maximum tangential extent, but this requires that none of the velocity offsets is a peculiar motion. The open symbols show analogues of SPT2349-56 found when we searched specifically for maximally extended filamentary structures in our N-body simulations. These simulated structures are not filaments; they are instead rather like collapsed structures that are slightly cigar-shaped. The SPT2349-56 galaxies could in principle be distributed like this, but it does not fundamentally change our discussion here. We also note that we are plotting two different things here: velocity offsets for SPT2349-56, and actual geometry (three-dimensional positions) for the simulation galaxies. Even though our search allowed for structures extending by about 5 Mpc along the line of sight (LOS), we found none that stretches beyond 1 Mpc. d, As for panel c, except that the full extent of our ALMA band 3 and 7 observations is shown. No structures are observed in the sidebands surrounding the 14 observed sources.
Rights and permissions
About this article
Cite this article
Miller, T.B., Chapman, S.C., Aravena, M. et al. A massive core for a cluster of galaxies at a redshift of 4.3. Nature 556, 469–472 (2018). https://doi.org/10.1038/s41586-018-0025-2
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1038/s41586-018-0025-2
This article is cited by
-
Predicted future fate of COSMOS galaxy protoclusters over 11 Gyr with constrained simulations
Nature Astronomy (2022)
-
Microwave spectro-polarimetry of matter and radiation across space and time
Experimental Astronomy (2021)
-
Spectroscopic confirmation of a mature galaxy cluster at a redshift of 2
Nature (2020)
-
The ancestors of most massive galaxy clusters
Nature Astronomy (2018)
Comments
By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.