Spectroscopic Identification of a Protocluster at z = 2.300: Environmental Dependence of Galaxy Properties at High Redshift

By C. Steidel, K. Adelberger, A. Shapley, D. Erb, Naveen A. Reddy, M. Pettini. 2005

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We have discovered a highly significant overdensity of galaxies at z = 2.300 ± 0.015 in the course of a redshift survey designed to select star-forming galaxies in the redshift range z = 2.3 ± 0.4 in the field of the bright z = 2.72 QSO HS 1700+643. The structure has a redshift-space galaxy overdensity of δ ≃ 7 and an estimated matter overdensity in real space of δm ≃ 1.8, indicating that it will virialize by z ~ 0 with a mass scale of ≃1.4 × 1015 M☉, that of a rich galaxy cluster. Detailed modeling of the spectral energy distribution—from the rest-frame far-UV to the rest-frame near-IR—of the 72 spectroscopically confirmed galaxies in this field for which we have obtained Ks and Spitzer IRAC photometry allows for a first direct comparison of galaxy properties as a function of large-scale environment at high redshift. We find that galaxies in the protocluster environment have mean stellar masses and inferred ages that are ~2 times larger (at z = 2.30) than identically UV-selected galaxies outside of the structure, and we show that this is consistent with simple theoretical expectations for the acceleration of structure formation in a region that is overdense on large scales by the observed amount. The protocluster environment contains a significant number of galaxies that already appear old, with large stellar masses (>1011 M☉), by z = 2.3.

Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/ea3b34080cbaf609cf1a7577cb707b71a3110cd5

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Citations in the corpus

Protoclusters associated with z > 2 radio galaxies - I. Characteristics of high redshift protoclusters (2006, background): “In recent years, several distant forming clusters (potoclusters) have been serendipitously discovered in field surveys (e.g., Steidel et al., 1998, 2005; Shimasaku et al., 2003; Ouchi et al., 2005).”
Galaxy Protoclusters as Drivers of Cosmic Star Formation History in the First 2 Gyr (2017, background): “Direct observations of z & 2 protoclusters have also shown a total SFR of hundreds to a few thousands M yr −1 in these extended regions (Steidel et al. 2005; Koyama et al. 2014; Casey et al. 2015).”
A SPITZER-SELECTED GALAXY CLUSTER AT z = 1.62 (2010, background): “However, this selection is biased potentially against clusters whose galaxies have had recent star formation (and overdensities of blue, star– forming galaxies at high redshift have been identified, e.g., Steidel et al. 2005).”
DUST OBSCURATION AND METALLICITY AT HIGH REDSHIFT: NEW INFERENCES FROM UV, Hα, AND 8 μm OBSERVATIONS OF z ∼ 2 STAR-FORMING GALAXIES (2010, methodology): “In addition to the longslit Hα spectroscopy, we targeted the z = 2.300 redshift overdensity in the HS1700+64 (“Q1700”) field (Steidel et al. 2005) with narrowband Brγ (2.17 µm/0.04 µm) observations that trace Hα at that redshift.”
ANCIENT LIGHT FROM YOUNG COSMIC CITIES: PHYSICAL AND OBSERVATIONAL SIGNATURES OF GALAXY PROTO-CLUSTERS (2013, methodology): “…a modification based on the insights 5 One can perform a correction based on the Zel’dovich approximation and assumptions of spherical symmetry and dynamical stage of the collapsing structures as in Steidel et al. (1998; see also Bardeen et al.1986; Steidel et al. 2005). drawn from simulations.”
Distant radio galaxies and their environments (2008, background): “…with several overdense regions found at large redshifts in the form of ”redshift spikes” or ”filaments” (e.g. Steidel et al 1998; Keel et al 1999; Steidel et al 2000; Möller and Fynbo 2001; Shimasaku et al 2003; Hayashino et al 2004; Matsuda et al 2005; Steidel et al 2005; Ouchi et al 2005).”
The Evolution of the Star Formation Activity in Galaxies and Its Dependence on Environment (2005, background): “Thus it could be the “primordial local density” at very high redshift that determines the properties (star formation history, morphology - and probably mass, see Steidel et al. 2005) of galaxies formed in that region.”
The first appearance of the red sequence of galaxies in proto-clusters at 2 <~ z <~ 3 (2007, methodology): “…radio galaxies using narrow-band imaging and/or spectroscopy in the optical (e.g., Kurk et al. 2000, Venemans et al. 2002; Venemans et al. 2007; Steidel et al. 2000; 2005), which in fact successfully found a number of over-dense regions at high redshifts traced by young star forming galaxies.”
Clusters of Galaxies in the First Half of the Universe from the IRAC Shallow Survey (2008, background): “Lyman break galaxy surveys with intensive follow-up spectroscopy on the Keck Telescopes have also identified highly overdense structures at z ¼ 2:30 and 3.09 (Steidel et al. 1998, 2005), and Ouchi & SXDS (2007) discuss a z ¼ 5:7 structure identified via Ly emission in a narrowband imaging survey.”
The realm of the galaxy protoclusters (2016, background): “…properties related to the kinematics, stellar populations and gas properties of galaxies inside and outside the overdense regions, provided that the spectra have sufficient signalto-noise and spectral resolution (e.g., Steidel et al., 2000, 2005; Cucciati et al., 2014; Lemaux et al., 2014).”
EVOLUTION OF THE COLOR–MAGNITUDE RELATION IN GALAXY CLUSTERS AT z ∼ 1 FROM THE ACS INTERMEDIATE REDSHIFT CLUSTER SURVEY (2008, background): “Steidel et al. (2005) find that protocluster galaxies are on average older and more massive than similar galaxies in the field, although there is no evidence for a correlation of morphology with environment at these redshifts (Peter et al. 2007; Overzier et al. 2008).”
A mature cluster with X-ray emission at z = 2.07 (2010, background): “While several overdensities of Lyα emitters atz > 2 have been reported (Pentericci et al. 1997, Miley et al. 2006, Steidel et al. 2005, Overzier et al. 2006), CL J1449+0856 is different in some key aspects because of the evidence of extended X-ray emission from an intra-cluster medium and a centre…”
On the evolution and environmental dependence of the star formation rate versus stellar mass relation since z ∼ 2 (2013, result): “We note that this trend is qualitatively consistent with some earlier studies showing a higher stellar masses in star-forming galaxies in z > 2 proto-clusters (e.g. Steidel et al. 2005; Kurk et al. 2009; Hatch et al. 2011; Matsuda et al. 2011; Koyama et al. 2013).”
SINFONI Integral Field Spectroscopy of z ~ 2 UV-selected Galaxies: Rotation Curves and Dynamical Evolution (2006, background): “…out, much of the signal leading to this high correlation length comes from a single field, which may bias the average result (see also the discussion by Steidel et al. 2005, who found a significant redshift overdensity for BX sources in another of the four fields used by Adelberger et al. 2005b).”
DIFFUSE Lyα EMITTING HALOS: A GENERIC PROPERTY OF HIGH-REDSHIFT STAR-FORMING GALAXIES (2011, methodology): “A galaxy over-density was again identified from spectroscopic follow-up, with z = 2.299± 0.03 (Shapley et al. 2005; Steidel et al. 2005).”