TY - JOUR
T1 - A Census of Galaxy Constituents in a Coma Progenitor Observed at z > 3
AU - Shi, Ke
AU - Lee, Kyoung Soo
AU - Dey, Arjun
AU - Huang, Yun
AU - Malavasi, Nicola
AU - Hung, Chao Ling
AU - Inami, Hanae
AU - Ashby, Matthew
AU - Duncan, Kenneth
AU - Xue, Rui
AU - Reddy, Naveen
AU - Hong, Sungryong
AU - Jannuzi, Buell T.
AU - Cooper, Michael C.
AU - Gonzalez, Anthony H.
AU - Röttgering, Huub J.A.
AU - Best, Phillip N.
AU - Tasse, Cyril
N1 - Funding Information:
Lee), which is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. The authors are honored to be permitted to conduct astronomical research on Iolkam Du’ag (Kitt Peak), a mountain with particular significance to the Tohono O’odham. This work was supported by a NASA Keck PI Data Award, administered by the NASA Exoplanet Science Institute. We thank NASA for its support, through grants NASA/JPL #1497290 and #1520350. This paper is based in part on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. This work is 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. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by NASA and the National Science Foundation. A.D.’s research was supported in part by NOAO, which is operated by AURA Inc. under a cooperative agreement with the National Science Foundation. This work was performed in part at the Aspen Center for Physics, supported by National Science Foundation grant PHY-1607611.
Publisher Copyright:
© 2019. The American Astronomical Society. All rights reserved.
PY - 2019/1/20
Y1 - 2019/1/20
N2 - We present a detailed census of galaxies in and around PC 217.96+32.3, a spectroscopically confirmed Coma analog at z = 3.78. Diverse galaxy types identified in the field include Lyα emitters (LAEs), massive star-forming galaxies, and ultramassive galaxies (≳ 10 11 M o ) which may have already halted their star formation. The sky distribution of the star-forming galaxies suggests the presence of a significant overdensity (δ SFG ≈ 8 ±2), which is spatially offset from the previously confirmed members by 3-4 Mpc to the west. Candidate quiescent and post-starburst galaxies are also found in large excess (a factor of ∼8-15 higher surface density than the field's), although their redshifts are less certain. We estimate that the total enclosed mass traced by the candidate star-forming galaxies is roughly comparable to that of PC 217.96+32.3 traced by the LAEs. We speculate that the true extent of PC 217.96+32.3 may be larger than previously known, half of which is missed by our LAE selection. Alternatively, the newly discovered overdensity may belong to another Coma progenitor not associated with PC 217.96+32.3. Expectations from theory suggest that both scenarios are equally unlikely (<1%) in the cosmic volume probed in our survey. If confirmed as a single structure, its total mass will be well in excess of Coma's, making it an exceptionally large cosmic structure rarely seen even in large cosmological simulations. Finally, we find that the protocluster galaxies follow the same star formation rate-M ∗ scaling relation as the field galaxies, suggesting that the environmental effect at z ∼ 4 is a subtle one at best for normal star-forming galaxies.
AB - We present a detailed census of galaxies in and around PC 217.96+32.3, a spectroscopically confirmed Coma analog at z = 3.78. Diverse galaxy types identified in the field include Lyα emitters (LAEs), massive star-forming galaxies, and ultramassive galaxies (≳ 10 11 M o ) which may have already halted their star formation. The sky distribution of the star-forming galaxies suggests the presence of a significant overdensity (δ SFG ≈ 8 ±2), which is spatially offset from the previously confirmed members by 3-4 Mpc to the west. Candidate quiescent and post-starburst galaxies are also found in large excess (a factor of ∼8-15 higher surface density than the field's), although their redshifts are less certain. We estimate that the total enclosed mass traced by the candidate star-forming galaxies is roughly comparable to that of PC 217.96+32.3 traced by the LAEs. We speculate that the true extent of PC 217.96+32.3 may be larger than previously known, half of which is missed by our LAE selection. Alternatively, the newly discovered overdensity may belong to another Coma progenitor not associated with PC 217.96+32.3. Expectations from theory suggest that both scenarios are equally unlikely (<1%) in the cosmic volume probed in our survey. If confirmed as a single structure, its total mass will be well in excess of Coma's, making it an exceptionally large cosmic structure rarely seen even in large cosmological simulations. Finally, we find that the protocluster galaxies follow the same star formation rate-M ∗ scaling relation as the field galaxies, suggesting that the environmental effect at z ∼ 4 is a subtle one at best for normal star-forming galaxies.
KW - cosmology: observations
KW - galaxies: clusters: general
KW - galaxies: evolution
KW - galaxies: formation
KW - galaxies: high-redshift
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U2 - 10.3847/1538-4357/aaf85d
DO - 10.3847/1538-4357/aaf85d
M3 - Article
AN - SCOPUS:85062038845
SN - 0004-637X
VL - 871
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 83
ER -