TY - JOUR
T1 - Megaparsec-scale structure around the protocluster core SPT2349-56 at z = 4.3
AU - Hill, Ryley
AU - Chapman, Scott
AU - Scott, Douglas
AU - Apostolovski, Yordanka
AU - Aravena, Manuel
AU - Béthermin, Matthieu
AU - Bradford, C. M.
AU - Canning, Rebecca E.A.
AU - De Breuck, Carlos
AU - Dong, Chenxing
AU - Gonzalez, Anthony
AU - Greve, Thomas R.
AU - Hayward, Christopher C.
AU - Hezaveh, Yashar
AU - Litke, Katrina
AU - Malkan, Matt
AU - Marrone, Daniel P.
AU - Phadke, Kedar
AU - Reuter, Cassie
AU - Rotermund, Kaja
AU - Spilker, Justin
AU - Vieira, Joaquin D.
AU - Weiß, Axel
N1 - Funding Information:
This paper makes use of the following ALMA data: ADS/JAO.ALMA#2017.1.00273.S, and ADS/JAO.ALMA#2018.1.00058.S. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), MOST and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO, and NAOJ. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 299.A-5045(A). The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. The SPT is supported by the National Science Foundation through grant PLR-1248097, with partial support through PHY-1125897, the Kavli Foundation and the Gordon and Betty Moore Foundation grant GBMF 947. This work was supported by the Natural Sciences and Engineering Research Council of Canada. The Flatiron Institute is supported by the Simons Foundation. MA has been supported by the grant ‘CONICYT+PCI+REDES 190194’. DPM, JDV, KCL, and KP acknowledge support from the US NSF under grants AST-1715213 and AST-1716127. KCL acknowledges support from the US NSF NRAO under grants SOSPA5-001 and SOSPA4-007, respectively. JDV acknowledges support from an Alfred P. Sloan Foundation Fellowship.
Publisher Copyright:
© 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.
PY - 2020/5/14
Y1 - 2020/5/14
N2 - We present an extensive ALMA spectroscopic follow-up programme of the $z\, {=}\, 4.3$ structure SPT2349-56, one of the most actively star-forming protocluster cores known, to identify additional members using their [C ii] 158 μm and CO(4-3) lines. In addition to robustly detecting the 14 previously published galaxies in this structure, we identify a further 15 associated galaxies at $z\, {=}\, 4.3$, resolving 55$\, {\pm }\,$5 per cent of the 870 μm flux density at 0.5 arcsec resolution compared to 21 arcsec single-dish data. These galaxies are distributed into a central core containing 23 galaxies extending out to 300 kpc in diameter, and a northern extension, offset from the core by 400 kpc, containing three galaxies. We discovered three additional galaxies in a red Herschel-SPIRE source 1.5 Mpc from the main structure, suggesting the existence of many other sources at the same redshift as SPT2349-56 that are not yet detected in the limited coverage of our data. An analysis of the velocity distribution of the central galaxies indicates that this region may be virialized with a mass of (9$\pm 5)\, {\times }\, 10^{12}$ M⊠, while the two offset galaxy groups are about 30 and 60 per cent less massive and show significant velocity offsets from the central group. We calculate the [C ii] and far-infrared number counts, and find evidence for a break in the [C ii] luminosity function. We estimate the average SFR density within the region of SPT2349-56 containing single-dish emission (a proper diameter of 720 kpc), assuming spherical symmetry, to be roughly 4$\, {\times }\, 10^4$ M⊠yr-1 Mpc-3; this may be an order of magnitude greater than the most extreme examples seen in simulations.
AB - We present an extensive ALMA spectroscopic follow-up programme of the $z\, {=}\, 4.3$ structure SPT2349-56, one of the most actively star-forming protocluster cores known, to identify additional members using their [C ii] 158 μm and CO(4-3) lines. In addition to robustly detecting the 14 previously published galaxies in this structure, we identify a further 15 associated galaxies at $z\, {=}\, 4.3$, resolving 55$\, {\pm }\,$5 per cent of the 870 μm flux density at 0.5 arcsec resolution compared to 21 arcsec single-dish data. These galaxies are distributed into a central core containing 23 galaxies extending out to 300 kpc in diameter, and a northern extension, offset from the core by 400 kpc, containing three galaxies. We discovered three additional galaxies in a red Herschel-SPIRE source 1.5 Mpc from the main structure, suggesting the existence of many other sources at the same redshift as SPT2349-56 that are not yet detected in the limited coverage of our data. An analysis of the velocity distribution of the central galaxies indicates that this region may be virialized with a mass of (9$\pm 5)\, {\times }\, 10^{12}$ M⊠, while the two offset galaxy groups are about 30 and 60 per cent less massive and show significant velocity offsets from the central group. We calculate the [C ii] and far-infrared number counts, and find evidence for a break in the [C ii] luminosity function. We estimate the average SFR density within the region of SPT2349-56 containing single-dish emission (a proper diameter of 720 kpc), assuming spherical symmetry, to be roughly 4$\, {\times }\, 10^4$ M⊠yr-1 Mpc-3; this may be an order of magnitude greater than the most extreme examples seen in simulations.
KW - galaxies: evolution
KW - galaxies: formation
UR - http://www.scopus.com/inward/record.url?scp=85091330644&partnerID=8YFLogxK
U2 - 10.1093/mnras/staa1275
DO - 10.1093/mnras/staa1275
M3 - Article
AN - SCOPUS:85091330644
VL - 495
SP - 3124
EP - 3159
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
SN - 0035-8711
IS - 3
ER -