Searching Far and Long. I. Pilot ALMA 2 mm Follow-up of Bright Dusty Galaxies as a Redshift Filter

Cooper, Olivia R.; Casey, Caitlin M.; Zavala, Jorge A.; Champagne, Jaclyn B.; Cunha, Elisabete da; Long, Arianna S.; Spilker, Justin; Staguhn, Johannes

doi:10.3847/1538-4357/ac616d

Cited by 15 publications

(21 citation statements)

References 131 publications

(179 reference statements)

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“…However, determining the contributions of dusty galaxies at very high redshifts has been challenging. Here we focus on whether the 2 mm data find significant star formation at high redshifts (here z > 5), and we make comparisons with the 2 mm results of Zavala et al (2021) and Cooper et al (2022).…”

Section: Mm-based Redshift Estimatesmentioning

confidence: 99%

“…By comparison, the 850 μm flux drops with these higher redshifts. Then, through the use of the 2 mm-870 μm flux ratio, one can try to estimate redshifts for these galaxies (e.g., Casey et al 2021;Cooper et al 2022). However, as we discuss in this paper, redshifts are better estimated using the flux ratio of 2 mm to a shorter bandpass, such as 450 μm, where the gradient is steeper (see Figure 1(b)).…”

Section: Introductionmentioning

confidence: 99%

“…Instead, the best method to select high-redshift DSFGs systematically remains submillimeter/millimeter surveys from largeaperture, ground-based telescopes, as these provide the fields of view necessary to detect significant samples. These samples can then be efficiently followed up with interferometric observations (e.g., Barger et al 2012;Hodge et al 2013;Cowie et al 2017Cowie et al , 2018Stach et al 2019;Cooper et al 2022;Cowie et al 2022). In fact, using single-dish priors can provide an enormous gain in speed over direct interferometric searches.…”

Section: Introductionmentioning

confidence: 99%

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2 mm Observations and the Search for High-redshift Dusty Star-forming Galaxies

Cowie

Barger

Bauer

2023

ApJ

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Finding high-redshift (z ≫ 4) dusty star-forming galaxies is extremely challenging. It has recently been suggested that millimeter selections may be the best approach since the negative K-correction makes galaxies at a given far-infrared luminosity brighter at z ≳ 4 than those at z = 2–3. Here we analyze this issue using a deep Atacama Large Millimeter/submillimeter Array (ALMA) 2 mm sample obtained by targeting ALMA 870 μm priors (these priors were the result of targeting SCUBA-2 850 μm sources) in the GOODS-S. We construct prior-based 2 mm galaxy number counts and compare them with published blank field-based 2 mm counts, finding good agreement down to 0.2 mJy. Only a fraction of the current 2 mm extragalactic background light is resolved, and we estimate what observational depths may be needed to resolve it fully. By complementing the 2 mm ALMA data with a deep SCUBA-2 450 μm sample, we exploit the steep gradient with a redshift of the 2 mm–450 μm flux density ratio to estimate redshifts for those galaxies without spectroscopic or robust optical/near-infrared photometric redshifts. Our observations measure galaxies with star formation rates in excess of 250 M ⊙ yr−1. For these galaxies, the star formation rate densities fall by a factor of 9 from z = 2–3 to z = 5–6.

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Section: Mm-based Redshift Estimatesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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2 mm Observations and the Search for High-redshift Dusty Star-forming Galaxies

Cowie

Barger

Bauer

2023

ApJ

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“…Each source in the sample has at least two ALMA measurements by our selection criteria, but 44 (77%) have four or more ALMA measurements (two have three ALMA bands and the remaining 11 have just two ALMA bands). Thus, the FIR SEDs of our sample are generally better sampled than others in the literature (e.g., da Cunha et al 2021;Cooper et al 2022).…”

Section: Robust Subset Selectionmentioning

confidence: 87%

“…In one such study, da Cunha et al (2021) used an optically thin modified blackbody (MBB) and found a median β = 1.9 ± 0.4 for a sample of 27 DSFGs from the ALESS survey (Hodge et al 2013;Karim et al 2013) with ALMA 870 μm and 2 mm data. In another study, Cooper et al (2022) used a combined general opacity blackbody and power-law fit and found a median β = 2.4 ± 0.3 for a sample of 39 DSFGs in the SSA22 field (850 μm flux >5.55 mJy) with SCUBA-2 850 μm, AzTEC 1.1 mm, and ALMA 2 mm data.…”

Section: Introductionmentioning

confidence: 99%

Dust Properties of 870 μm-selected Galaxies in GOODS-S

McKay

Barger

Cowie

et al. 2023

ApJ

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We analyze the dust properties of 57 870 μm-selected dusty star-forming galaxies in GOODS-S using new deep Atacama Large Millimeter/Submillimeter Array 1.2, 2, and 3 mm continuum imaging together with other far-infrared through millimeter data. We fit the spectral energy distributions (SEDs) with optically thin modified blackbodies to constrain the emissivity indices and effective dust temperatures, finding a median emissivity index of β = 1.78 − 0.25 + 0.43 and a median temperature of T d = 33.6 − 5.4 + 12.1 K. We observe a negative correlation between β and T d . By testing several SED models, we determine that the derived emissivity indices can be influenced by opacity assumptions. Our temperature measurements are consistent with no evolution in dust temperature with redshift.

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COSMOS2020: The galaxy stellar mass function

Weaver¹,

Davidzon²,

Toft³

et al. 2023

A&A

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Context. How galaxies form, assemble, and cease their star formation is a central question within the modern landscape of galaxy evolution studies. These processes are indelibly imprinted on the galaxy stellar mass function (SMF), and its measurement and understanding is key to uncovering a unified theory of galaxy evolution. Aims. We present constraints on the shape and evolution of the galaxy SMF, the quiescent galaxy fraction, and the cosmic stellar mass density across 90% of the history of the Universe from z = 7.5 → 0.2 as a means to study the physical processes that underpin galaxy evolution. Methods. The COSMOS survey is an ideal laboratory for studying representative galaxy samples. Now equipped with deeper and more homogeneous near-infrared coverage exploited by the COSMOS2020 catalog, we leverage the large 1.27 deg2 effective area to improve sample statistics and understand spatial variations (cosmic variance) – particularly for rare, massive galaxies – and push to higher redshifts with greater confidence and mass completeness than previous studies. We divide the total stellar mass function into star-forming and quiescent subsamples through NUVrJ color-color selection. The measurements are then fit with single- and double-component Schechter functions to infer the intrinsic galaxy stellar mass function, the evolution of its key parameters, and the cosmic stellar mass density out to z = 7.5. Finally, we compare our measurements to predictions from state-of-the-art cosmological simulations and theoretical dark matter halo mass functions. Results. We find a smooth, monotonic evolution in the galaxy stellar mass function since z = 7.5, in general agreement with previous studies. The number density of star-forming systems have undergone remarkably consistent growth spanning four decades in stellar mass from z = 7.5 → 2 whereupon high-mass systems become predominantly quiescent (“downsizing”). Meanwhile, the assembly and growth of low-mass quiescent systems only occurred recently, and rapidly. An excess of massive systems at z ≈ 2.5 − 5.5 with strikingly red colors, with some being newly identified, increase the observed number densities to the point where the SMF cannot be reconciled with a Schechter function. Conclusions. Systematics including cosmic variance and/or active galactic nuclei contamination are unlikely to fully explain this excess, and so we speculate that they may be dust-obscured populations similar to those found in far infrared surveys. Furthermore, we find a sustained agreement from z ≈ 3 − 6 between the stellar and dark matter halo mass functions for the most massive systems, suggesting that star formation in massive halos may be more efficient at early times.

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Searching Far and Long. I. Pilot ALMA 2 mm Follow-up of Bright Dusty Galaxies as a Redshift Filter

Cited by 15 publications

References 131 publications

2 mm Observations and the Search for High-redshift Dusty Star-forming Galaxies

2 mm Observations and the Search for High-redshift Dusty Star-forming Galaxies

Dust Properties of 870 μm-selected Galaxies in GOODS-S

COSMOS2020: The galaxy stellar mass function

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