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1. Close-up view of a luminous star-forming galaxy at z = 2.95

   https://doi.org/10.1051/0004-6361/202039743  

   Berta, S. ; Young, A. J. ; Cox, P. ; Neri, R. ; Jones, B. M. ; Baker, A. J. ; Omont, A. ; Dunne, L. ; Carnero Rosell, A. ; Marchetti, L. ; et al ( February 2021 , Astronomy & Astrophysics)

   Exploiting the sensitivity of the IRAM NOrthern Extended Millimeter Array (NOEMA) and its ability to process large instantaneous bandwidths, we have studied the morphology and other properties of the molecular gas and dust in the star forming galaxy, H-ATLAS J131611.5+281219 (HerBS-89a), at z = 2.95. High angular resolution (0 . ″3) images reveal a partial 1 . ″0 diameter Einstein ring in the dust continuum emission and the molecular emission lines of 12 CO(9−8) and H 2 O(2 02  − 1 11 ). Together with lower angular resolution (0 . ″6) images, we report the detection of a series of molecular lines including the three fundamental transitions of the molecular ion OH + , namely (1 1  − 0 1 ), (1 2  − 0 1 ), and (1 0  − 0 1 ), seen in absorption; the molecular ion CH + (1 − 0) seen in absorption, and tentatively in emission; two transitions of amidogen (NH 2 ), namely (2 02  − 1 11 ) and (2 20  − 2 11 ) seen in emission; and HCN(11 − 10) and/or NH(1 2  − 0 1 ) seen in absorption. The NOEMA data are complemented with Very Large Array data tracing the 12 CO(1 − 0) emission line, which provides a measurement ofmore »the total mass of molecular gas and an anchor for a CO excitation analysis. In addition, we present Hubble Space Telescope imaging that reveals the foreground lensing galaxy in the near-infrared (1.15  μ m). Together with photometric data from the Gran Telescopio Canarias, we derive a photometric redshift of z phot = 0.9 −0.5 +0.3 for the foreground lensing galaxy. Modeling the lensing of HerBS-89a, we reconstruct the dust continuum (magnified by a factor μ  ≃ 5.0) and molecular emission lines (magnified by μ  ∼ 4 − 5) in the source plane, which probe scales of ∼0 . ″1 (or 800 pc). The 12 CO(9 − 8) and H 2 O(2 02  − 1 11 ) emission lines have comparable spatial and kinematic distributions; the source-plane reconstructions do not clearly distinguish between a one-component and a two-component scenario, but the latter, which reveals two compact rotating components with sizes of ≈1 kpc that are likely merging, more naturally accounts for the broad line widths observed in HerBS-89a. In the core of HerBS-89a, very dense gas with n H 2  ∼ 10 7 − 9 cm −3 is revealed by the NH 2 emission lines and the possible HCN(11 − 10) absorption line. HerBS-89a is a powerful star forming galaxy with a molecular gas mass of M mol  = (2.1 ± 0.4) × 10 11   M ⊙ , an infrared luminosity of L IR  = (4.6 ± 0.4) × 10 12   L ⊙ , and a dust mass of M dust  = (2.6 ± 0.2) × 10 9   M ⊙ , yielding a dust-to-gas ratio δ GDR  ≈ 80. We derive a star formation rate SFR = 614 ± 59  M ⊙ yr −1 and a depletion timescale τ depl  = (3.4 ± 1.0) × 10 8 years. The OH + and CH + absorption lines, which trace low (∼100 cm −3 ) density molecular gas, all have their main velocity component red-shifted by Δ V  ∼ 100 km s −1 relative to the global CO reservoir. We argue that these absorption lines trace a rare example of gas inflow toward the center of a galaxy, indicating that HerBS-89a is accreting gas from its surroundings.« less
2. The HH 24 Complex: Jets, Multiple Star Formation, and Orphaned Protostars

   https://doi.org/10.3847/1538-3881/acadd4  

   Reipurth, Bo ; Bally, J. ; Yen, Hsi-Wei ; Arce, H. G. ; Rodríguez, L.-F. ; Raga, A. C. ; Geballe, T. R. ; Rao, R. ; Comerón, F. ; Mikkola, S. ; et al ( April 2023 , The Astronomical Journal)

   Abstract The HH 24 complex harbors five collimated jets emanating from a small protostellar multiple system. We have carried out a multiwavelength study of the jets, their driving sources, and the cloud core hosting the embedded stellar system, based on data from the Hubble Space Telescope, Gemini, Subaru, Apache Point Observatory 3.5 m, Karl G. Jansky Very Large Array, and Atacama Large Millimeter/submillimeter Array (ALMA) telescopes. The data show that the multiple system, SSV 63, contains at least 7 sources, ranging in mass from the hydrogen-burning limit to proto-Herbig Ae stars. The stars are in an unstable nonhierarchical configuration, and one member, a borderline brown dwarf, is moving away from the protostellar system with 25 km s −1 , after being ejected ∼5800 yr ago as an orphaned protostar. Five of the embedded sources are surrounded by small, possibly truncated, disks resolved at 1.3 mm with ALMA. Proper motions and radial velocities imply jet speeds of 200–300 km s −1 . The two main HH 24 jets, E and C, form a bipolar jet system that traces the innermost portions of parsec-scale chains of Herbig–Haro and H 2 shocks with a total extent of at least 3 pc. H 2more »CO and C 18 O observations show that the core has been churned and continuously fed by an infalling streamer. 13 CO and 12 CO trace compact, low-velocity, cavity walls carved by the jets and an ultracompact molecular outflow from the most embedded object. Chaotic N -body dynamics likely will eject several more of these objects. The ejection of stars from their feeding zones sets their masses. Dynamical decay of nonhierarchical systems can thus be a major contributor to establishing the initial mass function.« less
3. Rise of the Titans: Gas Excitation and Feedback in a Binary Hyperluminous Dusty Starburst Galaxy at z ∼ 6

   https://doi.org/10.3847/1538-4357/abcf2e  

   Riechers, Dominik A. ; Nayyeri, Hooshang ; Burgarella, Denis ; Emonts, Bjorn H. ; Clements, David L. ; Cooray, Asantha ; Ivison, Rob J. ; Oliver, Seb ; Pérez-Fournon, Ismael ; Rigopoulou, Dimitra ; et al ( January 2021 , The Astrophysical Journal)

   Abstract We report new observations toward the hyperluminous dusty starbursting major merger ADFS-27 ( z  = 5.655), using the Australia Telescope Compact Array (ATCA) and the Atacama Large Millimeter/submillimeter Array (ALMA). We detect CO ( J  = 2 → 1), CO ( J  = 8 → 7), CO ( J  = 9 → 8), CO ( J  = 10 → 9), and H 2 O (3 12  → 2 21 ) emission, and a P Cygni−shaped OH + (1 1  → 0 1 ) absorption/emission feature. We also tentatively detect H 2 O (3 21  → 3 12 ) and OH + (1 2 → 0 1 ) emission and CH + ( J  = 1 → 0) absorption. We find a total cold molecular mass of M gas  = (2.1 ± 0.2) × 10 11 ( α CO /1.0) M ⊙ . We also find that the excitation of the star-forming gas is overall moderate for a z > 5 dusty starburst, which is consistent with its moderate dust temperature. A high-density, high kinetic temperature gas component embedded in the gas reservoir is required to fully explain the CO line ladder. This component is likely associated with the “maximum starburst” nuclei in the two merging galaxies, which are separated by only 140 ± 13 km s −1 along the line of sightmore »and 9.0 kpc in projection. The kinematic structure of both components is consistent with galaxy disks, but this interpretation remains limited by the spatial resolution of the current data. The OH + features are only detected toward the northern component, which is also the one that is more enshrouded in dust and thus remains undetected up to 1.6 μ m even in our sensitive new Hubble Space Telescope Wide Field Camera 3 imaging. The absorption component of the OH + line is blueshifted and peaks near the CO and continuum emission peak, while the emission is redshifted and peaks offset by 1.7 kpc from the CO and continuum emission peak, suggesting that the gas is associated with a massive molecular outflow from the intensely star-forming nucleus that supplies 125 M ⊙ yr −1 of enriched gas to its halo.« less
4. Discovery of a Protocluster Core Associated with an Enormous Lya Nebula at z = 2.3

   https://doi.org/10.3847/1538-4357/ac29c6  

   Li, Qiong ; Wang, Ran ; Dannerbauer, Helmut ; Cai, Zheng ; Emonts, Bjorn ; Prochaska, Jason Xavier ; Battaia, Fabrizio Arrigoni ; Neri, Roberto ; Zhang, Chengpeng ; Fan, Xiaohui ; et al ( December 2021 , The Astrophysical Journal)

   Abstract The MAMMOTH-1 nebula at z = 2.317 is an enormous Ly α nebula (ELAN) extending to a ∼440 kpc scale at the center of the extreme galaxy overdensity BOSS 1441. In this paper, we present observations of the CO(3 − 2) and 250 GHz dust-continuum emission from MAMMOTH-1 using the IRAM NOrthern Extended Millimeter Array. Our observations show that CO(3 − 2) emission in this ELAN has not extended widespread emission into the circum- and inter-galactic media. We also find a remarkable concentration of six massive galaxies in CO(3 − 2) emission in the central ∼100 kpc region of the ELAN. Their velocity dispersions suggest a total halo mass of M 200 c ∼ 10 13.1 M ⊙ , marking a possible protocluster core associated with the ELAN. The peak position of the CO(3 − 2) line emission from the obscured AGN is consistent with the location of the intensity peak of MAMMOTH-1 in the rest-frame UV band. Its luminosity line ratio between the CO(3 − 2) and CO(1 − 0) r 3,1 is 0.61 ± 0.17. The other five galaxies have CO(3 − 2) luminosities in the range of (2.1–7.1) × 10 9 K km s −1 pcmore »2 , with the star-formation rates derived from the 250 GHz continuum of (<36)–224 M ⊙ yr −1 . Follow-up spectroscopic observations will further confirm more member galaxies and improve the accuracy of the halo mass estimation.« less
5. Molecular gas in z ∼ 6 quasar host galaxies

   https://doi.org/10.1051/0004-6361/202142871  

   Decarli, Roberto ; Pensabene, Antonio ; Venemans, Bram ; Walter, Fabian ; Bañados, Eduardo ; Bertoldi, Frank ; Carilli, Chris L. ; Cox, Pierre ; Fan, Xiaohui ; Farina, Emanuele Paolo ; et al ( June 2022 , Astronomy & Astrophysics)

   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 ], ormore »[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.« less