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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.

 

We present a detailed overview of the science goals and predictions for the Prime-Cam direct-detection camera–spectrometer being constructed by the CCAT-prime collaboration for dedicated use on the Fred Young Submillimeter Telescope (FYST). The FYST is a wide-field, 6 m aperture submillimeter telescope being built (first light in late 2023) by an international consortium of institutions led by Cornell University and sited at more than 5600 m on Cerro Chajnantor in northern Chile. Prime-Cam is one of two instruments planned for FYST and will provide unprecedented spectroscopic and broadband measurement capabilities to address important astrophysical questions ranging from Big Bang cosmology through reionization and the formation of the first galaxies to star formation within our own Milky Way. Prime-Cam on the FYST will have a mapping speed that is over 10 times greater than existing and near-term facilities for high-redshift science and broadband polarimetric imaging at frequencies above 300 GHz. We describe details of the science program enabled by this system and our preliminary survey strategies.

 

We report CO(5 → 4) and CO(6 → 5) line observations in the dusty starbursting galaxy CRLE (z= 5.667) and the main-sequence (MS) galaxy HZ10 (z= 5.654) with the Northern Extended Millimeter Array. CRLE is the most luminousz> 5 starburst in the COSMOS field and HZ10 is the most gas-rich “normal” galaxy currently known atz> 5. We find line luminosities for CO(5 → 4) and CO(6 → 5) of (4.9 ± 0.5) and (3.8 ± 0.4) × 10¹⁰K km s⁻¹pc²for CRLE and upper limits of < 0.76 and < 0.60 × 10¹⁰K km s⁻¹pc²for HZ10, respectively. The CO excitation of CRLE appears comparable to otherz> 5 dusty star-forming galaxies. For HZ10, these line luminosity limits provide the first significant constraints of this kind for an MS galaxy atz> 5. We find the upper limit of$L_{5\to 4}^{\prime }/L_{2\to 1}^{\prime }$in HZ10 could be similar to the average value for MS galaxies aroundz≈ 1.5, suggesting that MS galaxies with comparable gas excitation may already have existed one billion years after the Big Bang. For CRLE we determine the most likely values for the H₂density, kinetic temperature, and dust temperature based on excitation modeling of the CO line ladder. We also derive a total gas mass of (7.1 ± 1.3) × 10¹⁰M_⊙. Our findings provide some of the currently most detailed constraints on the gas excitation that sets the conditions for star formation in a galaxy protocluster environment atz> 5.

 

Aims.We have implemented a novel method to create simulated [CII] emission line intensity mapping (LIM) data cubes using COSMOS 2020 galaxy catalogue data. It allows us to provide solid lower limits for previous simulation-based model predictions and the expected signal strength of upcoming surveys.

Methods.We applied [CII]158 μm luminosity models to COSMOS 2020 to create LIM cubes covering a 1.2 × 1.2deg²sky area. These models were derived using galaxy bulk property data from the ALPINE-ALMA survey over the redshift range of 4.4 < z < 5.9, while additional models were taken from the literature. The LIM cubes cover 3.42 < z < 3.87, 4.14 < z < 4.76, 5.34 < z < 6.31, and 6.75 < z < 8.27, matched to planned observations from the EoR-Spec module of the Prime-Cam instrument in the Fred Young Submillimeter Telescope (FYST). We also created predictions including additional galaxies below current detection limits by ‘extrapolating’ from the faint end of the COSMOS 2020 luminosity function, comparing these to predictions from the literature. In addition, we computed the signal-to-noise (S/N) ratios for the power spectra, using parameters from the planned FYST survey with predicted instrumental noise levels.

Results.We find lower limits for the expected power spectrum using the likely incomplete empirical data: when normalised by 2π², the amplitudes atk = 1 Mpc⁻¹are 3.06 × 10⁷, 1.43 × 10⁷, 9.80 × 10⁵, 2.77 × 10⁵ (Jy sr⁻¹)²for the aforementioned redshift ranges. For the extrapolated sample, the power spectra are consistent with prior predictions, indicating that extrapolation is a viable method for creating mock LIM cubes. In this case, we expect a result of S/N> 1 when using FYST parameters. However, our high-redshift results remain inconclusive because of the poor completeness of COSMOS 2020 atz > 6.3. These predictions will be improved on the basis of future JWST data.

 

WISE J224607.6–052634.9 (W2246–0526) is a hot dust-obscured galaxy atz = 4.601, and the most luminous obscured quasar known to date. W2246–0526 harbors a heavily obscured supermassive black hole that is most likely accreting above the Eddington limit. We present observations with the Atacama Large Millimeter/submillimeter Array (ALMA) in seven bands, including band 10, of the brightest far-infrared (FIR) fine-structure emission lines of this galaxy: [OI]_63 μm, [OIII]_88 μm, [NII]_122 μm, [OI]_145 μm, [CII]_158 μm, [NII]_205 μm, [CI]_370 μm, and [CI]_609 μm. A comparison of the data to a large grid of CLOUDYradiative transfer models reveals that a high hydrogen density (n_H ∼ 3 × 10³cm⁻³) and extinction (A_V ∼ 300 mag), together with extreme ionization (log(U) = − 0.5) and a high X-ray to UV ratio (α_ox ≥ −0.8) are required to reproduce the observed nuclear line ratios. The values ofα_oxandUare among the largest found in the literature and imply the existence of an X-ray-dominated region (XDR). In fact, this component explains the a priori very surprising non-detection of the [OIII]_88 μmemission line, which is actually suppressed, instead of boosted, in XDR environments. Interestingly, the best-fitted model implies higher X-ray emission and lower CO content than what is detected observationally, suggesting the presence of a molecular gas component that should be further obscuring the X-ray emission over larger spatial scales than the central region that is being modeled. These results highlight the need for multiline infrared observations to characterize the multiphase gas in high redshift quasars and, in particular, W2246–0526 serves as an extreme benchmark for comparisons of interstellar medium conditions with other quasar populations at cosmic noon and beyond.

 

The Fred Young Submillimeter Telescope (FYST), which is the telescope of the CCAT-prime project, will be located at 5600 m near the summit of Cerro Chajnantor in northern Chile, and will host the modular instrument called Prime-Cam. Two of the instrument modules in Prime-Cam will be a spectrometer with a resolving power of R ∼ 100 and populated with a detector array of several thousand KIDs (Kinetic Inductance Detectors). The main science goal of this spectrometer module, called EoR-Spec, is to probe the Epoch of Reionization (EoR) in the early universe using the Line Intensity Mapping (LIM) technique with the redshifted [CII] fine-structure line. This presentation provides an overview of the optical, mechanical, and spectral design of EoR-Spec, as well as of the detector array that will be used. The optical design consists of four silicon lenses that have anti-reflection metamaterial layers. A scanning Fabry-Perot Interferometer (FPI) will be located at the pupil and provides the spectral resolution over the full spectral coverage of 210 GHz to 420 GHz in two orders, resulting in a redshift coverage of the [CII] line from z = 3.5 to z = 8. The detector array consists of three subarrays of KIDs, two of which are tuned for the frequency range between 210 GHz and 315 GHz, and one that is tuned for the 315 GHz to 420 GHz range. The angular resolution will be between about 30'' to 50''. This presentation also addresses the spectral and spatial scanning strategy of EoR-Spec on FYST. EoR-Spec is expected to be installed into Prime-Cam about 1 year after first light of FYST. 

We investigate the molecular gas content of z  ∼ 6 quasar host galaxies using the Institut de Radioastronomie Millimétrique Northern Extended Millimeter Array. We targeted the 3 mm dust continuum, and the line emission from CO(6–5), CO(7–6), and [C  I ] 2−1 in ten infrared–luminous quasars that have been previously studied in their 1 mm dust continuum and [C  II ] line emission. We detected CO(7–6) at various degrees of significance in all the targeted sources, thus doubling the number of such detections in z  ∼ 6 quasars. The 3 mm to 1 mm flux density ratios are consistent with a modified black body spectrum with a dust temperature T dust  ∼ 47 K and an optical depth τ ν  = 0.2 at the [C  II ] frequency. Our study provides us with four independent ways to estimate the molecular gas mass, M H2 , in the targeted quasars. This allows us to set constraints on various parameters used in the derivation of molecular gas mass estimates, such as the mass per luminosity ratios α CO and α [CII] , the gas-to-dust mass ratio δ g/d , and the carbon abundance [C]/H 2 . Leveraging either on the dust, CO, [C  I ], or [C  II ] emission yields mass estimates of the entire sample in the range M H2  ∼ 10 10 –10 11 M ⊙ . We compared the observed luminosities of dust, [C  II ], [C  I ], and CO(7–6) with predictions from photo-dissociation and X-ray dominated regions. We find that the former provide better model fits to our data, assuming that the bulk of the emission arises from dense ( n H  > 10 4 cm −3 ) clouds with a column density N H  ∼ 10 23 cm −2 , exposed to a radiation field with an intensity of G 0  ∼ 10 3 (in Habing units). Our analysis reiterates the presence of massive reservoirs of molecular gas fueling star formation and nuclear accretion in z  ∼ 6 quasar host galaxies. It also highlights the power of combined 3 mm and 1 mm observations for quantitative studies of the dense gas content in massive galaxies at cosmic dawn. 

Abstract We present a high-resolution study of the cold molecular gas as traced by CO(1-0) in the unlensed z ∼ 3.4 submillimeter galaxy SMM J13120+4242, using multiconfiguration observations with the Karl G. Jansky Very Large Array (JVLA). The gas reservoir, imaged on 0.″39 (∼3 kpc) scales, is resolved into two components separated by ∼11 kpc with a total extent of 16 ± 3 kpc. Despite the large spatial extent of the reservoir, the observations show a CO(1-0) FWHM linewidth of only 267 ± 64 km s −1 . We derive a revised line luminosity of L CO ( 1 − 0 ) ′ = (10 ± 3) × 10 10 K km s −1 pc 2 and a molecular gas mass of M gas = (13 ± 3)× 10 10 ( α CO /1) M ⊙ . Despite the presence of a velocity gradient (consistent with previous resolved CO(6-5) imaging), the CO(1-0) imaging shows evidence for significant turbulent motions that are preventing the gas from fully settling into a disk. The system likely represents a merger in an advanced stage. Although the dynamical mass is highly uncertain, we use it to place an upper limit on the CO-to-H 2 mass conversion factor α CO of 1.4. We revisit the SED fitting, finding that this galaxy lies on the very massive end of the main sequence at z = 3.4. Based on the low gas fraction, short gas depletion time, and evidence for a central AGN, we propose that SMM J13120 is in a rapid transitional phase between a merger-driven starburst and an unobscured quasar. The case of SMM J13120 highlights how mergers may drive important physical changes in galaxies without pushing them off the main sequence. 

We present Karl G. Jansky Very Large Array S - (2–4 GHz), C - (4–8 GHz), and X -band (8–12 GHz) continuum observations toward seven radio-loud quasars at z  > 5. This sample has previously been found to exhibit spectral peaks at observed-frame frequencies above ∼1 GHz. We also present upgraded Giant Metrewave Radio Telescope (uGMRT) band-2 (200 MHz), band-3 (400 MHz), and band-4 (650 MHz) radio continuum observations toward eight radio-loud quasars at z  > 5, selected from our previous GMRT survey, in order to sample their low-frequency synchrotron emission. Combined with archival radio continuum observations, all ten targets show evidence for spectral turnover. The turnover frequencies are ∼1–50 GHz in the rest frame, making these targets gigahertz-peaked-spectrum or high-frequency-peaker candidates. For the nine well-constrained targets with observations on both sides of the spectral turnover, we fit the entire radio spectrum with absorption models associated with synchrotron self-absorption and free-free absorption (FFA). Our results show that FFA in an external inhomogeneous medium can accurately describe the observed spectra for all nine targets, which may indicate an FFA origin for the radio spectral turnover in our sample. As for the complex spectrum of J114657.79+403708.6 at z  = 5.00 with two spectral peaks, it may be caused by multiple components (i.e., core-jet) and FFA by the high-density medium in the nuclear region. However, we cannot rule out the spectral turnover origin of variability. Based on our radio spectral modeling, we calculate the radio loudness R 2500 Å for our sample, which ranges from 12 −1 +1 to 674 −51 +61 .