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1. ALMA Reveals Extended Cool Gas and Hot Ionized Outflows in a Typical Star-forming Galaxy at Z = 7.13

   https://doi.org/10.3847/1538-4357/ac795b  

   Akins, Hollis B. ; Fujimoto, Seiji ; Finlator, Kristian ; Watson, Darach ; Knudsen, Kirsten K. ; Richard, Johan ; C. Bakx, Tom J. L. ; Hashimoto, Takuya ; Inoue, Akio K. ; Matsuo, Hiroshi ; et al ( July 2022 , The Astrophysical Journal)

   We present spatially resolved morphological properties of [CII] 158μm, [OIII] 88μm, dust, and rest-frame ultraviolet (UV) continuum emission for A1689-zD1, a strongly lensed, sub-L* galaxy atz= 7.13, by utilizing deep Atacama Large Millimeter/submillimeter Array (ALMA) and Hubble Space Telescope (HST) observations. While the [OIII] line and UV continuum are compact, the [CII] line is extended up to a radius ofr∼ 12 kpc. Using multi-band rest-frame far-infrared continuum data ranging from 52 to 400μm, we find an average dust temperature and emissivity index of$T_{\mathrm{dust}}={41}_{-14}^{+17}$K and$\beta ={1.7}_{-0.7}^{+1.1}$, respectively, across the galaxy. We find slight differences in the dust continuum profiles at different wavelengths, which may indicate that the dust temperature decreases with distance. We map the star formation rate (SFR) via IR and UV luminosities and determine a total SFR of 37 ± 1M_⊙yr⁻¹with an obscured fraction of 87%. While the [OIII] line is a good tracer of the SFR, the [CII] line shows deviation from the localL_[CII]-SFR relations in the outskirts of the galaxy. Finally, we observe a clear difference in the line profile between [CII] and [OIII], with significant residuals (∼5σ) in the [OIII] line spectrum after subtracting a single Gaussian model. This suggests a possible origin of the extended [CII] structure from the cooling of hot ionized outflows. The extended [CII] and high-velocity [OIII] emission may both contribute in part to the highL_[OIII]/L_[CII]ratios recently reported inz> 6 galaxies.

    

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2. Jansky Very Large Array Detections of CO(1–0) Emission in H i-absorption-selected Galaxies at z ≳ 2

   https://doi.org/10.3847/2041-8213/ac7bdd  

   Kaur, B. ; Kanekar, N. ; Rafelski, M. ; Neeleman, M. ; Prochaska, J. X. ; Revalski, M. ( July 2022 , The Astrophysical Journal Letters)

   We report a Karl G. Jansky Very Large Array search for redshifted CO(1–0) emission from three Hi-absorption-selected galaxies atz≈ 2, identified earlier in their CO(3–2) or CO(4–3) emission. We detect CO(1–0) emission from DLA B1228-113 atz≈ 2.1933 and DLA J0918+1636 atz≈ 2.5848; these are the first detections of CO(1–0) emission in high-zHi-selected galaxies. We obtain high molecular gas masses,M_mol≈ 10¹¹× (α_CO/4.36)M_⊙, for the two objects with CO(1–0) detections, which are a factor of ≈1.5–2 lower than earlier estimates. We determine the excitation of the mid-JCO rotational levels relative to theJ= 1 level,r_J1, in Hi-selected galaxies for the first time, obtainingr₃₁= 1.00 ± 0.20 andr₄₁= 1.03 ± 0.23 for DLA J0918+1636, andr₃₁= 0.86 ± 0.21 for DLA B1228-113. These values are consistent with thermal excitation of theJ= 3 andJ= 4 levels. The excitation of theJ= 3 level in the Hi-selected galaxies is similar to that seen in massive main-sequence and submillimeter galaxies atz≳2, but higher than that in main-sequence galaxies atz≈ 1.5; the higher excitation of the galaxies atz≳ 2 is likely to be due to their higher star formation rate (SFR) surface density. We use Hubble Space Telescope Wide Field Camera 3 imaging to detect the rest-frame near-ultraviolet (NUV) emission of DLA B1228-113, obtaining an NUV SFR of 4.44 ± 0.47M_⊙yr⁻¹, significantly lower than that obtained from the total infrared luminosity, indicating significant dust extinction in thez≈ 2.1933 galaxy.

    

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3. Discovery of a Dusty, Chemically Mature Companion to a z ∼ 4 Starburst Galaxy in JWST ERS Data

   https://doi.org/10.3847/2041-8213/acb59c  

   Peng, Bo ; Vishwas, Amit ; Stacey, Gordon ; Nikola, Thomas ; Lamarche, Cody ; Rooney, Christopher ; Ball, Catie ; Ferkinhoff, Carl ; Spoon, Henrik ( February 2023 , The Astrophysical Journal Letters)

   We report the discovery of two companion sources to a strongly lensed galaxy SPT0418-47 (“ring”) at redshift 4.225, targeted by the JWST Early Release Science program. We confirm that these sources are at a similar redshift to the ring based on Hαdetected in the NIRSpec spectrum and [Cii]λ158μm line from the Atacama Large Millimeter/submillimeter Array (ALMA). Using multiple spectral lines detected in JWST/NIRSpec, the rest-frame optical to infrared images from NIRCam and MIRI and far-infrared dust continuum detected by ALMA, we argue that the newly discovered sources are actually lensed images of the same companion galaxy SPT0418-SE, hereafter referred to “SE,” located within 5 kpc in the source plane of the ring. The star formation rate derived using [Cii] and the dust continuum puts a lower limit of 17M_☉yr⁻¹, while the SFR_Hαis estimated to be >2 times lower, thereby confirming that SE is a dust-obscured star-forming galaxy. Analysis using optical strong line diagnostics suggests that SE has near-solar elemental abundance, while the ring appears to have supersolar metallicity O/H and N/O. We attempt to reconcile the high metallicity in this system by invoking early onset of star formation with continuous high star-forming efficiency or by suggesting that optical strong line diagnostics need revision at high redshift. We suggest that SPT0418-47 resides in a massive dark-matter halo with yet-to-be-discovered neighbors. This work highlights the importance of joint analysis of JWST and ALMA data for a deep and complete picture of the early universe.

    

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4. Two Massive, Compact, and Dust-obscured Candidate z ≃ 8 Galaxies Discovered by JWST

   https://doi.org/10.3847/1538-4357/acef21  

   Akins, Hollis B. ; Casey, Caitlin M. ; Allen, Natalie ; Bagley, Micaela B. ; Dickinson, Mark ; Finkelstein, Steven L. ; Franco, Maximilien ; Harish, Santosh ; Arrabal Haro, Pablo ; Ilbert, Olivier ; et al ( October 2023 , The Astrophysical Journal)

   We present a search for extremely red, dust-obscured,z> 7 galaxies with JWST/NIRCam+MIRI imaging over the first 20 arcmin²of publicly available Cycle 1 data from the COSMOS-Web, CEERS, and PRIMER surveys. Based on their red color in F277W−F444W (∼2.5 mag) and detection in MIRI/F770W (∼25 mag), we identify two galaxies, COS-z8M1 and CEERS-z7M1, that have best-fit photometric redshifts of$z={8.4}_{-0.4}^{+0.3}$and${7.6}_{-0.1}^{+0.1}$, respectively. We perform spectral energy distribution fitting with a variety of codes (includingbagpipes,prospector,beagle, andcigale) and find a >95% probability that these indeed lie atz> 7. Both sources are compact (R_eff≲ 200 pc) and highly obscured (A_V∼ 1.5–2.5) and, at our best-fit redshift estimates, likely have strong [Oiii]+Hβemission contributing to their 4.4μm photometry. We estimate stellar masses of ∼10¹⁰M_⊙for both sources; by virtue of detection in MIRI at 7.7μm, these measurements are robust to the inclusion of bright emission lines, for example, from an active galactic nucleus. We identify a marginal (2.9σ) Atacama Large Millimeter/submillimeter Array detection at 2 mm within 0.″5 of COS-z8M1, which, if real, would suggest a remarkably high IR luminosity of ∼10¹²L_⊙. These two galaxies, if confirmed atz∼ 8, would be extreme in their stellar and dust masses and may be representative of a substantial population of highly dust-obscured galaxies at cosmic dawn.

    

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5. ALMA multiline survey of the ISM in two quasar host–companion galaxy pairs at z > 6

   https://doi.org/10.1051/0004-6361/202039696  

   Pensabene, A. ; Decarli, R. ; Bañados, E. ; Venemans, B. ; Walter, F. ; Bertoldi, F. ; Fan, X. ; Farina, E. P. ; Li, J. ; Mazzucchelli, C. ; et al ( August 2021 , Astronomy & Astrophysics)

   null (Ed.)

   We present a multiline survey of the interstellar medium (ISM) in two z  > 6 quasar host galaxies, PJ231−20 ( z  = 6.59) and PJ308−21 ( z  = 6.23), and their two companion galaxies. Observations were carried out using the Atacama Large (sub-)Millimeter Array (ALMA). We targeted 11 transitions including atomic fine-structure lines (FSLs) and molecular lines: [NII] 205 μm , [CI] 369 μm , CO ( J up  = 7, 10, 15, 16), H 2 O 3 12  − 2 21 , 3 21  − 3 12 , 3 03  − 2 12 , and the OH 163 μm doublet. The underlying far-infrared (FIR) continuum samples the Rayleigh-Jeans tail of the respective dust emission. By combining this information with our earlier ALMA [CII] 158 μm observations, we explored the effects of star formation and black hole feedback on the ISM of the galaxies using the CLOUDY radiative transfer models. We estimated dust masses, spectral indexes, IR luminosities, and star-formation rates from the FIR continuum. The analysis of the FSLs indicates that the [CII] 158 μm and [CI] 369 μm emission arises predominantly from the neutral medium in photodissociation regions (PDRs). We find that line deficits agree with those of local luminous IR galaxies. The CO spectral line energy distributions (SLEDs) reveal significant high- J CO excitation in both quasar hosts. Our CO SLED modeling of the quasar PJ231−20 shows that PDRs dominate the molecular mass and CO luminosities for J up  ≤ 7, while the J up  ≥ 10 CO emission is likely driven by X-ray dissociation regions produced by the active galactic nucleus (AGN) at the very center of the quasar host. The J up  > 10 lines are undetected in the other galaxies in our study. The H 2 O 3 21  − 3 12 line detection in the same quasar places this object on the L H 2 O  −  L TIR relation found for low- z sources, thus suggesting that this water vapor transition is predominantly excited by IR pumping. Models of the H 2 O SLED and of the H 2 O-to-OH 163 μm ratio point to PDR contributions with high volume and column density ( n H  ∼ 0.8 × 10 5 cm −3 , N H  = 10 24 cm −2 ) in an intense radiation field. Our analysis suggests a less highly excited medium in the companion galaxies. However, the current data do not allow us to definitively rule out an AGN in these sources, as suggested by previous studies of the same objects. This work demonstrates the power of multiline studies of FIR diagnostics in order to dissect the physical conditions in the first massive galaxies emerging from cosmic dawn. 

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