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— Histogram vs redshift showing the photometric redshifts of galaxies in the IRAC Shallow Survey. The area covered by the solid red histogram is 3 ′ × 3 ′ around the z = 1.41 cluster. The solid black histogram represents the average of 100 3 ′ × 3 ′ patches randomly chosen from the entire ∼9 degree 2 IRAC survey in the Boötes field. The dashed histograms represent the 1 and 2 σ uncertainties on the average value histogram.
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We report the discovery of a galaxy cluster at z = 1.41. ISCS J143809+341419 was found in the Spitzer/IRAC Shallow Survey of the Boötes field in the NOAO Deep Wide-Field Survey carried out using IRAC. The cluster candidate was initially identified as a high-density region of objects with photometric redshifts in the range 1.3 < z < 1.5. Optical spe...
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Citations
... The Spitzer Adaptation of the Red-Sequence Cluster Survey (SpARCS; [171,172,185]) identified clusters using z − 3.6 µm color selection at z > 1 over 42 deg 2 with multi-wavelength coverage and was the basis of follow-up optical spectroscopic campaigns for the well-studied Gemini Cluster Astrophysics Spectroscopic Survey (GCLASS; 10 clusters at 0.85 < z < 1.34; [34]) and Gemini Observations of Galaxies in Rich Early Environments (GOGREEN; 21 groups and clusters at 1 < z < 1.5; [186]) samples, which will be discussed extensively in Section 4. The IRAC Shallow and Distant Cluster Surveys (ISCS/IDCS; [169,187]) used extensive multiwavelength coverage in the 8.5 deg 2 Boötes field to identify >300 log M 200 /M ∼ 13.8 cluster candidates from 0.1 < z < 2 as overdensities using robust photometric redshifts [165]. Spectroscopy from the AGN and Galaxy Evolution Survey (AGES; [188]) and targeted follow-up [165,169,175,[189][190][191][192] were used to confirm >120 clusters in this sample and halo mass measurements were made using X-ray, SZ, and weak lensing as well as statistical arguments [187,190,[193][194][195][196][197][198]. Substantial M/FIR follow-up was obtained for this sample as well, adding to the available X-ray to NIR photometry [199]; this survey will be discussed extensively in Section 5. We note two additional surveys covering up to ∼100 deg 2 : ∼1,000 group and low-mass cluster candidates were identified using the Red Sequence cluster finder redMapper [200] in the 24 deg 2 Spitzer-HETDEX Exploratory Large Area survey (SHELA; [201]) and 279 cluster candidates at z > 1.3 were identified using color selection in the 94 deg 2 Spitzer South Pole Telescope Deep Field survey (SSDF; [202]). ...
Environment is one of the primary drivers of galaxy evolution; via multiple mechanisms, it can control the critical process of transforming galaxies from star forming to quiescent, commonly termed “quenching”. Despite its importance, however, we still do not have a clear view of how environmentally-driven quenching proceeds even in the most extreme environments: galaxy clusters and their progenitor proto-clusters. Recent advances in infrared capabilities have enabled transformative progress not only in the identification of these structures but in detailed analyses of quiescence, obscured star formation, and molecular gas in (proto-)cluster galaxies across cosmic time. In this review, we will discuss the current state of the literature regarding the quenching of galaxies in (proto-)clusters from the observational, infrared perspective. Our improved understanding of environmental galaxy evolution comes from unique observables across the distinct regimes of the near-, mid-, and far-infrared, crucial in the push to high redshift where massive galaxy growth is dominated by highly extinct, infrared-bright galaxies.
... Studies that analyze cluster galaxies (both as individual objects and in aggregate) at z < 1 suggest that massive galaxies in clusters form stars in an epoch of early and rapid star formation (at z > ∼3), before quickly settling into a mode of quiescent evolution (Dressler & Gunn 1982;Stanford et al. 1998;Balogh et al. 1999;Dressler et al. 2004;Stanford et al. 2005;Holden et al. 2005;Mei et al. 2006). Thus, observations of clusters at higher redshifts should sample an epoch where this star formation-or at least its end stages-is observed in situ. ...
... Second, to conduct evolutionary studies and characterize the precursors of lower-redshift clusters, we need to study the appropriate antecedents of lower-redshift massive clusters-which are high-redshift lower-mass systems. This is a no-trivial sample to build; z > 1 systems measured with these observations are few in number (Stanford et al. 2005(Stanford et al. , 2014Brodwin et al. 2006Brodwin et al. , 2011Elston et al. 2006;Wilson et al. 2006;Eisenhardt et al. 2008;Muzzin et al. 2009;Papovich et al. 2010;Demarco et al. 2010;Santos et al. 2011;Gettings et al. 2012;Zeimann et al. 2012;Gonzalez et al. 2015;Balogh et al. 2017;Paterno-Mahler et al. 2017). Third, a challenge with optical and IR cluster surveys is whether the selection of galaxy clusters based on member galaxy properties systematically affects the studies of the said galaxies, e.g., while red-sequence selection of clusters has proven extremely fruitful for finding clusters and groups across a broad range of mass and redshift, it remains a concern whether this selection biases our understanding of quiescent (i.e., red sequence) cluster galaxies, particularly at higher redshifts. ...
Using stellar population synthesis models to infer star formation histories (SFHs), we analyze photometry and spectroscopy of a large sample of quiescent galaxies that are members of Sunyaev–Zel’dovich (SZ)-selected galaxy clusters across a wide range of redshifts. We calculate stellar masses and mass-weighted ages for 837 quiescent cluster members at 0.3 < z < 1.4 using rest-frame optical spectra and the Python-based Prospector framework, from 61 clusters in the SPT-GMOS Spectroscopic Survey (0.3 < z < 0.9) and three clusters in the SPT Hi-z cluster sample (1.25 < z < 1.4). We analyze spectra of subpopulations divided into bins of redshift, stellar mass, cluster mass, and velocity-radius phase-space location, as well as by creating composite spectra of quiescent member galaxies. We find that quiescent galaxies in our data set sample a diversity of SFHs, with a median formation redshift (corresponding to the lookback time from the redshift of observation to when a galaxy forms 50% of its mass, t 50 ) of z = 2.8 ± 0.5, which is similar to or marginally higher than that of massive quiescent field and cluster galaxy studies. We also report median age–stellar mass relations for the full sample (age of the universe at t 50 (Gyr) = 2.52 (±0.04)–1.66 (±0.12) log 10 ( M /10 ¹¹ M ⊙ )) and recover downsizing trends across stellar mass; we find that massive galaxies in our cluster sample form on aggregate ∼0.75 Gyr earlier than lower-mass galaxies. We also find marginally steeper age–mass relations at high redshifts, and report a bigger difference in formation redshifts across stellar mass for fixed environment, relative to formation redshifts across environment for fixed stellar mass.
... Our sample consists of 126 cluster galaxies selected from 11 massive (log M 200 /M e ∼ 14) galaxy clusters at z = 1-1.75 with uniquely deep Herschel/PACS imaging at 100 and 160 μm. The clusters are drawn from the IRAC Shallow and IRAC Distant Cluster Surveys (ISCS and IDCS, respectively; Eisenhardt et al. 2008;Stanford et al. 2012), identified as near-infrared (NIR) (stellar mass) overdensities in (R.A., Decl., photometric redshift) space and confirmed via targeted spectroscopic follow-up (Stanford et al. 2005Brodwin et al. 2006Brodwin et al. , 2011Brodwin et al. , 2013Elston et al. 2006;Eisenhardt et al. 2008;Zeimann et al. 2012Zeimann et al. , 2013. We note that these 11 clusters were chosen for follow-up based on their being significant overdensities, and not on the basis of their SF activity, which shows considerable variation from cluster to cluster. ...
We present the average gas properties derived from Atacama Large Millimeter Array (ALMA) Band 6 dust continuum imaging of 126 massive (log M ⋆ / M ⊙ ≳ 10.5), star-forming cluster galaxies across 11 galaxy clusters at z = 1–1.75. Using stacking analysis on the ALMA images, combined with UV–far-infrared data, we quantify the average infrared spectral energy distributions (SEDs) and gas properties (molecular gas masses, M mol ;gas depletion timescales, τ depl ; and gas fractions, f gas ) as functions of cluster-centric radius and properties including stellar mass and distance from the main sequence. We find a significant dearth in the ALMA fluxes relative to that expected in the field—with correspondingly low M mol and f gas , and short τ depl —with weak or no dependence on cluster-centric radius out to twice the virial radius. The Herschel+ALMA SEDs indicate warmer dust temperatures (∼36–38 K) than coeval field galaxies (∼30 K). We perform a thorough comparison of the cluster galaxy gas properties to field galaxies, finding deficits of 2–3×, 3–4×, and 2–4× in M mol , τ depl , and f gas compared to coeval field stacks, and larger deficits compared to field scaling relations built primarily on detections. The cluster gas properties derived here are comparable with stacking analyses of (proto-)clusters in the literature, and at odds with findings of field-like τ depl and enhanced f gas reported using CO and dust continuum detections. Our analysis suggests that environment has a considerable impact on gas properties out to large radii, in good agreement with cosmological simulations which project that gas depletion begins beyond the virial radius and largely completes by first passage of the cluster core.
... This cluster catalog comprises ∼300 cluster candidates between 0.1 < z < 2, with ∼100 candidates at z > 1. Clusters are identified as overdensities of 4.5 µm flux selected galaxies in three-dimensional (RA, DEC, photometric redshift) space using a wavelet detection algorithm . At high redshift, more than 20 clusters from the sample have been spectroscopically confirmed (Stanford et al. 2005;Eisenhardt et al. 2008;Brodwin et al. 2006Brodwin et al. , 2011Brodwin et al. , 2013Zeimann et al. 2013), and the rate of contamination by spurious line-of-sight associations is expected to be ∼ 10% over the sample (Eisenhardt et al. 2008). From clustering measurements and halo mass ranking simulations, the median halo mass of the cluster sample is log M 200 /M ∼ 13.8 − 13.9 and does not change within the redshift range of our study (Brodwin et al. 2007;Lin et al. 2013;Alberts et al. 2014). ...
Combined observations from UV to IR wavelengths are necessary to fully account for the star-formation in galaxy clusters. Low mass (log M/Msun<10) galaxies are typically not individualy detected, particularly at higher redshifts (z~1-2) where galaxy clusters are undergoing rapid transitions from hosting mostly active, dust-obscured star-forming galaxies to quiescent, passive galaxies. To account for these undetected galaxies, we measure the total light emerging from GALEX/NUV stacks of galaxy clusters between z=0.5-1.6. Combined with existing measurements from Spitzer, WISE, and Herschel, we study the average UV through far-infrared (IR) spectral energy distribution (SED) of clusters. From the SEDs, we measure the total stellar mass and amount of dust-obscured and unobscured star-formation arising from all cluster-member galaxies, including the low mass population. The relative fraction of unobscured star-formation we observe in the UV is consistent with what is observed in field galaxies. There is tentative evidence for lower than expected unobscured star-formation at z~0.5, which may arise from rapid redshift evolution in the low mass quenching efficiency in clusters reported by other studies. Finally, the GALEX data places strong constraints on derived stellar-to-halo mass ratios at z<1 which anti-correlate with the total halo mass, consistent with trends found from local X-ray observations of clusters. The data exhibit steeper slopes than implementations of the cluster star-formation efficiency in semi-analytical models.
... Studies that analyze cluster galaxies (both as individual objects and in aggregate) at z < 1 suggest that mas-sive galaxies in clusters form stars in an epoch of early and rapid star formation (at z >∼ 3), before quickly settling into a mode of quiescent evolution (Dressler & Gunn 1982;Stanford et al. 1998;Balogh et al. 1999;Dressler et al. 2004;Stanford et al. 2005a;Holden et al. 2005;Mei et al. 2006). Thus, observations of clusters at higher redshifts should sample an epoch where this star formation -or at least its end stages -is observed in situ. ...
Using stellar population synthesis models to infer star formation histories (SFHs), we analyse photometry and spectroscopy of a large sample of quiescent galaxies which are members of Sunyaev-Zel'dovich (SZ)-selected galaxy clusters across a wide range of redshifts. We calculate stellar masses and mass-weighted ages for 837 quiescent cluster members at 0.3 < z < 1.4 using rest-frame optical spectra and the Python-based Prospector framework, from 61 clusters in the SPT-GMOS Spectroscopic Survey (0.3 < z < 0.9) and 3 clusters in the SPT Hi-z cluster sample (1.25 < z < 1.4). We analyse spectra of subpopulations divided into bins of redshift, stellar mass, cluster mass, and velocity-radius phase-space location, as well as by creating composite spectra of quiescent member galaxies. We find that quiescent galaxies in our dataset sample a diversity of SFHs, with a median formation redshift (corresponding to the lookback time from the redshift of observation to when a galaxy forms 50% of its mass, t$_{50}$) of $z=2.8\pm0.5$, which is similar to or marginally higher than that of massive quiescent field and cluster galaxy studies. We also report median age-stellar mass relations for the full sample (age of the Universe at $t_{50}$ (Gyr) = $2.52 (\pm0.04) - 1.66 (\pm0.11)$ log$_{10}(M/10^{11} M\odot))$ and recover downsizing trends across stellar mass; we find that massive galaxies in our cluster sample form on aggregate $\sim0.75$ Gyr earlier than lower mass galaxies. We also find marginally steeper age-mass relations at high redshifts, and report a bigger difference in formation redshifts across stellar mass for fixed environment, relative to formation redshifts across environment for fixed stellar mass.
... This assumption has permitted to associate directly the SN Ia rate per unit mass, measured in a sample of clusters at redshift z, with the DTD at a delay t delay corresponding to the time elapsed between the formation redshift, z f , and the cluster redshift z. The short-burst assumption is likely justified, at least when analyzing clusters at z 1. Spectral analyses of the stellar populations of cluster galaxies have long shown that the bulk of their stars were formed quickly at z f ∼ 3 − 4 (e.g., Daddi et al. 2000;Stanford et al. 2005;Eisenhardt et al. 2008;Snyder et al. 2012;Stalder et al. 2013;Andreon et al. 2014Andreon et al. , 2016. Most recently, Salvador-Rusiñol et al. (2019) have analysed the ultraviolet-to-optical absorption lines in the high-signalto-noise stacked spectra of tens of thousands of massive early-type galaxies at z ∼ 0.4, and have set a stringent limit of < 0.5% on the fraction of these galaxies' stellar mass formed in the prior 2 Gyr. ...
The delay time distribution (DTD) of Type-Ia supernovae (SNe Ia) is the rate of SNe Ia, as a function of time, that explode in a hypothetical stellar population of unit mass, formed in a brief burst at time $t=0$, and is important for understanding chemical evolution, SN Ia progenitors, and SN Ia physics. Past estimates of the DTD in galaxy clusters have been deduced from SN Ia rates measured in cluster samples observed at various redshifts, corresponding to different time intervals after a presumed initial brief burst of star formation. Recently, Friedmann and Maoz analysed a cluster sample at $z=1.13-1.75$ and confirmed indications from previous studies of lower-redshift clusters, that the DTD has a power-law form whose normalisation is at least several times higher than measured in field-galaxy environments, implying that SNe Ia are produced in larger numbers by the stellar populations in clusters. This conclusion, however, could have been affected by the implicit assumption that the stars were formed in a single brief starburst at high $z$. Here, we re-derive the DTD from the cluster SN Ia data, but now relax the single-burst assumption. Instead, we allow for a range of star-formation histories and dust extinctions for each cluster. Via MCMC modeling, we simultaneously fit, using stellar population synthesis models and DTD models, the integrated galaxy-light photometry in several bands and the SN Ia numbers discovered in each cluster. With these more-realistic assumptions, we find a best-fit DTD with power-law index $\alpha=-1.09_{-0.12}^{+0.15}$, and amplitude, at delay $t=1~\rm Gyr$, $R_1=0.41_{-0.10}^{+0.12}\times 10^{-12}~{\rm yr}^{-1}{\rm M}_\odot^{-1}$. The derived cluster-environment DTD remains higher (at $3.8\sigma$ significance) than the field-galaxy DTD, by a factor $\sim 2-3$. Cluster and field DTDs both have consistent slopes of $\alpha\approx -1.1$.
... Spectroscopic follow-up of ISCS cluster candidates, shown in Fig. 1, by the AGN and Galaxy Evolution Survey (Kochanek et al. 2012) has confirmed dozens of clusters at z < 1. At z > 1, over 20 of the ISCS clusters have been spectroscopically confirmed through targeted follow-up with the Low-Resolution Imaging Spectrometer on Keck (Oke et al. 1995) or Hubble Space Telescope Wide Field Camera 3 (Kimble et al. 2008) spectroscopy (see Stanford et al. 2005;Brodwin et al. 2006Brodwin et al. , 2011Elston et al. 2006; (Kochanek et al. 2012), Keck (Stanford et al. 2005;Brodwin et al. 2006;Elston et al. 2006;Eisenhardt et al. 2008), and HST Zeimann et al. 2013). The dotted lines show the scatter in cluster photometric redshift accuracy, σ = 0.036 (1 + z). ...
... Spectroscopic follow-up of ISCS cluster candidates, shown in Fig. 1, by the AGN and Galaxy Evolution Survey (Kochanek et al. 2012) has confirmed dozens of clusters at z < 1. At z > 1, over 20 of the ISCS clusters have been spectroscopically confirmed through targeted follow-up with the Low-Resolution Imaging Spectrometer on Keck (Oke et al. 1995) or Hubble Space Telescope Wide Field Camera 3 (Kimble et al. 2008) spectroscopy (see Stanford et al. 2005;Brodwin et al. 2006Brodwin et al. , 2011Elston et al. 2006; (Kochanek et al. 2012), Keck (Stanford et al. 2005;Brodwin et al. 2006;Elston et al. 2006;Eisenhardt et al. 2008), and HST Zeimann et al. 2013). The dotted lines show the scatter in cluster photometric redshift accuracy, σ = 0.036 (1 + z). ...
Massive galaxy clusters undergo strong evolution from z ∼ 1.6 to z ∼ 0.5, with overdense environments at high-z characterized by abundant dust-obscured star formation and stellar mass growth which rapidly give way to widespread quenching. Data spanning the near- to far- infrared (IR) can directly trace this transformation; however, such studies have largely been limited to the massive galaxy end of cluster populations. In this work, we present “total light” stacking techniques spanning 3.4 − 500 μm aimed at revealing the total cluster emission, including low-mass members and potential intracluster dust. We detail our procedures for WISE, Spitzer, and Herschel imaging, including corrections to recover the total stacked emission in the case of high fractions of detected galaxies. We apply our techniques to 232 well-studied log M200/M⊙ ∼ 13.8 clusters in multiple redshift bins, recovering extended cluster emission at all wavelengths. We measure the averaged IR radial profiles and spectral energy distributions (SEDs), quantifying the total stellar and dust content. The near-IR profiles are well described by an NFW model with a high (c ∼ 7) concentration. Dust emission is similarly concentrated, albeit suppressed at r ≲ 0.3 Mpc. The measured SEDs lack warm dust, consistent with the colder SEDs of low-mass galaxies. We derive total stellar masses consistent with the theoretical Mhalo − M⋆ relation and specific-star formation rates that evolve strongly with redshift, echoing that of log M⋆/M⊙ ≳ 10 cluster galaxies. Separating out the massive population reveals the majority of cluster far-IR emission ($\sim 70-80\%$) is provided by the low-mass constituents, which differs from field galaxies. This effect may be a combination of mass-dependent quenching and excess dust in low-mass cluster galaxies.
... Massive galaxy clusters are now identified as early as ≈ 2 by searching for overdensities of red, early-type galaxies (e.g. Gladders & Yee 2000;Stanford et al. 2005;Wilson et al. 2006;Eisenhardt et al. 2008;Papovich et al. 2010;Tanaka et al. 2010;Gobat et al. 2011;Wylezalek et al. 2014;Noirot et al. 2016). These methods require near-and mid-infrared (IR) observations for redshifts 1, and have been successful at identifying structures in the early Universe. ...
We present APEX-LABOCA 870 micron observations of the fields surrounding the nine brightest, high-redshift, unlensed objects discovered in the South Pole Telescope's (SPT) 2500 square degrees survey. Initially seen as point sources by SPT's 1-arcmin beam, the 19-arcsec resolution of our new data enables us to deblend these objects and search for submillimetre (submm) sources in the surrounding fields. We find a total of 98 sources above a threshold of 3.7 sigma in the observed area of 1300 square arcminutes, where the bright central cores resolve into multiple components. After applying a radial cut to our LABOCA sources to achieve uniform sensitivity and angular size across each of the nine fields, we compute the cumulative and differential number counts and compare them to estimates of the background, finding a significant overdensity of approximately 10 at 14 mJy. The large overdensities of bright submm sources surrounding these fields suggest that they could be candidate protoclusters undergoing massive star-formation events. Photometric and spectroscopic redshifts of the unlensed central objects range from 3 to 7, implying a volume density of star-forming protoclusters of approximately 0.1 per giga-parsec cube. If the surrounding submm sources in these fields are at the same redshifts as the central objects, then the total star-formation rates of these candidate protoclusters reach 10,000 solar masses per year, making them much more active at these redshifts than what has been seen so far in both simulations and observations.
... Spectroscopic follow-up of ISCS cluster candidates, shown in Figure 1, by the AGN and Galaxy Evolution Survey (AGES; Kochanek et al. 2012) has confirmed dozens of clusters at z < 1. At z > 1, over 20 of the ISCS clusters have been spectroscopically confirmed through targeted follow-up with the Low Resolution Imaging Spectrometer (LRIS) on Keck (Oke et al. 1995) or Hubble Space T elescope Wide Field Camera 3 (WFC3; Kimble et al. 2008) spectroscopy (see Stanford et al. 2005;Elston et al. 2006;Brodwin et al. 2006Brodwin et al. , 2011Eisenhardt et al. 2008;Zeimann et al. 2012;Brodwin et al. 2013;Zeimann et al. 2013). The photometric redshift accuracy for the confirmed ISCS clusters is σ = 0.036 (1 + z). ...
... Data reduction, catalog creation, and completeness simulations of the Böotes SPIRE maps used in this work are described in Alberts et al. (2014). (Stanford et al. 2005;Elston et al. 2006;Brodwin et al. 2006;Eisenhardt et al. 2008), and HST Zeimann et al. 2013). The dotted lines show the scatter in cluster photometric redshift accuracy, σ = 0.036 (1 + z). ...
Massive galaxy clusters undergo strong evolution from z~1.6 to z~0.5, with overdense environments at high-z characterized by abundant dust-obscured star formation and stellar mass growth which rapidly give way to widespread quenching. Data spanning the near- to far-infrared (IR) spectrum can directly trace this transformation; however, such studies have largely been limited to the massive galaxy end of cluster populations. In this work, we present ``total light" stacking techniques spanning 3.4-500{\mu}m aimed at revealing the total cluster IR emission, including low mass members and potential intracluster dust. We detail our procedures for WISE, Spitzer, and Herschel imaging, including corrections to recover the total stacked emission in the case of high fractions of detected galaxies. We apply our stacking techniques to 232 well-studied massive (log M200/Msun~13.8) clusters across multiple z bins, recovering extended cluster emission at all wavelengths, typically at >5sigma. We measure the averaged near- to far-IR radial profiles and SEDs, quantifying the total stellar and dust content. The near-IR radial profiles are well described by an NFW model with a high (c~7) concentration parameter. Dust emission is similarly concentrated, albeit suppressed at small radii (r<0.2Mpc). The measured SEDs lack warm dust, consistent with the colder SEDs expected for low mass galaxies. We derive total stellar masses consistent with the theoretical Mhalo-M_star relation and specific-star formation rates that evolve strongly with redshift, echoing that of massive (log Mstar/Msun>10) cluster galaxies. Separating out the massive galaxy population reveals that the majority of cluster far-IR emission (~70-80%) is provided by the low mass constituents, which differs from field galaxies. This effect may be a combination of mass-dependent quenching and excess dust in low mass cluster galaxies.
... Shallow yet wide surveys, in particular the IRAC Shallow Survey, enabled detections of many high-redshift clusters (102,103,104). More discoveries were made in the Spitzer Wide-Area Infrared Extragalactic (SWIRE) Survey using a simple color excess in Spitzer bands [105]. ...
When did galaxies start forming stars? What is the role of distant galaxies in galaxy formation models and the epoch of reionization? What are the conditions in typical star-forming galaxies at redshifts >~4? Why is galaxy evolution dependent on environment? The Spitzer Space Telescope has been a crucial tool for addressing these questions. Accurate knowledge of stellar masses, ages and star formation rates requires measuring rest-frame optical (and ultraviolet) light, which only Spitzer can probe at high redshifts for a sufficiently large sample of typical galaxies. Many of these science goals are the main science drivers for the James Webb Space Telescope, and Spitzer afforded us their first exploration.
