We present observations of the ground state 1$_{0,1}$-0$_{0,0}$ rotational transition of HDO at 464.925 GHz and the 1$_{1,0}$-1$_{0,1}$ transition at 509.292 GHz toward the three high-mass star forming regions: G34.26+0.15, W49N, and W51e$_{1}$/e$_{2}$, carried out with the Caltech Submillimeter Observatory. The latter transition is observed for the first time from the ground. The spectra are modeled, together with observations of higher-energy HDO transitions, as well as submillimeter dust continuum fluxes from the literature, using a spherically symmetric radiative transfer model to derive the radial distribution of the HDO abundance in the target sources. The abundance profile is divided into an inner hot core region, with kinetic temperatures higher than 100~K, and a cold outer envelope with lower kinetic temperatures. The derived HDO abundance with respect to H$_2$ is (0.3-3.7)$\times 10^{-8}$ in the hot inner region ($T > 100 \mathrm{K}$) and (7.0-10.0)$\times 10^{-11}$ in the cold outer envelope. We also used two H$_{2}^{18}$O fundamental transitions to constrain the H$_{2}$O abundances in the outer envelopes. The HDO/H$_{2}$O ratios in these cold regions are found to be (1.8-3.1)$\times 10^{-3}$ and are consequently higher than in the hot inner regions of these sources.
Using a broadband, high spectral resolution survey toward Orion KL acquired with Herschel/HIFI as part of the HEXOS key program, we derive the abundances of H$_2$O and HDO in the different spatial/velocity components associated with this massive star-forming region: the Hot Core, Compact Ridge, and Plateau. A total of 20 transitions of H$_2$$^{18}$O, 14 of H$_2$$^{17}$O, 37 of HD$^{16}$O, 6 of HD$^{18}$O, and 6 of D$_2$O are used in the analysis, spanning from ground state transitions to over 1200 K in upper-state energy. Low-excitation lines are detected in multiple components, but the highes…
We report the first detection of deuterated water (HDO) toward an extragalactic hot core. The HDO 2$_{11}$-2$_{12}$ line has been detected toward hot cores N105-2A and 2B in the N105 star-forming region in the low-metallicity Large Magellanic Cloud (LMC) dwarf galaxy with the Atacama Large Millimeter/submillimeter Array (ALMA). We have compared the HDO line luminosity ($L_{\rm HDO}$) measured toward the LMC hot cores to those observed toward a sample of seventeen Galactic hot cores covering three orders of magnitude in $L_{\rm HDO}$, four orders of magnitude in bolometric luminosity ($L_{\rm b…
Understanding water deuterium fractionation is important for constraining the mechanisms of water formation in interstellar clouds. Observations of HDO and H$_2^{18}$O transitions were carried out towards the high-mass star-forming region G34.26+0.15 with the HIFI instrument onboard the Herschel Space Observatory, as well as with ground-based single-dish telescopes. Ten HDO lines and three H$_2^{18}$O lines covering a broad range of upper energy levels (22-204 K) were detected. We used a non-LTE 1D analysis to determine the HDO/H$_2$O ratio as a function of radius in the envelope. Models with …
Aims. The aim of this paper is to study deuterated water in the solar-type protostars NGC1333 IRAS4A and IRAS4B, to compare their HDO abundance distribution with other star-forming regions, and to constrain their HDO/H2O ratios. Methods. Using the Herschel/HIFI instrument as well as ground-based telescopes, we observed several HDO lines covering a large excitation range (Eup/k=22-168 K) towards these protostars and an outflow position. Non-LTE radiative transfer codes were then used to determine the HDO abundance profiles in these sources. Results. The HDO fundamental line profiles show a very…
Although water is an essential and widespread molecule in star-forming regions, its chemical formation pathways are still not very well constrained. Observing the level of deuterium fractionation of OH, a radical involved in the water chemical network, is a promising way to infer its chemical origin. We aim at understanding the formation mechanisms of water by investigating the origin of its deuterium fractionation. This can be achieved by observing the abundance of OD towards the low-mass protostar IRAS16293-2422, where the HDO distribution is already known. Using the GREAT receiver on board …
Although deuterium enrichment of water may provide an essential piece of information in the understanding of the formation of comets and protoplanetary systems, only a few studies up to now have aimed at deriving the HDO/H2O ratio in low-mass star forming regions. Previous studies of the molecular deuteration toward the solar-type class 0 protostar, IRAS 16293-2422, have shown that the D/H ratio of water is significantly lower than other grain-surface-formed molecules. It is not clear if this property is general or particular to this source. In order to see if the results toward IRAS 16293-242…
We present the first results of a pilot program to conduct an ALMA Band 10 spectral line survey of the high-mass star-forming region NGC 6334I. The observations were taken in exceptional weather conditions (0.19 mm precipitable water) with typical system temperatures $T_{\rm{sys}}$ $<$950 K at $\sim$890 GHz. A bright, bipolar north-south outflow is seen in HDO and CS emission, driven by the embedded massive protostar MM1B. This has allowed, for the first time, a direct comparison of the thermal water in this outflow to the location of water maser emission from prior 22 GHz VLA observations. Th…
Recent observations of the HDO/H$_2$O ratio toward protostars in isolated and clustered environments show an apparent dichotomy, where isolated sources show higher D/H ratios than clustered counterparts. Establishing which physical and chemical processes create this differentiation can provide insights into the chemical evolution of water during star formation and the chemical diversity during the star formation process and in young planetary systems. Methods: The evolution of water is modeled using 3D physicochemical models of a dynamic star-forming environment. The physical evolution during …
We present Herschel/HIFI observations of 30 transitions of water isotopologues toward the high-mass star forming region NGC 6334 I. The line profiles of H_2^{16}O, H_2^{17}O, H_2^{18}O, and HDO show a complex pattern of emission and absorption components associated with the embedded hot cores, a lower-density envelope, two outflow components, and several foreground clouds, some associated with the NGC 6334 complex, others seen in projection against the strong continuum background of the source. Our analysis reveals an H2O ortho/para ratio of 3 +/- 0.5 in the foreground clouds, as well as the o…
Aims: Using the unprecedented combination of high resolution and sensitivity offered by ALMA, we aim to investigate whether and how hot corinos, circumstellar disks, and ejected gas are related in young solar-mass protostars. Methods: We observed CH$_3$CHO and deuterated water (HDO) high-excitation ($E_{\rm u}$ up to 335 K) lines towards the Sun-like protostar HH212--MM1. Results: For the first time, we have obtained images of CH$_3$CHO and HDO emission in the inner $\simeq$ 100 AU of HH212. The multifrequency line analysis allows us to contrain the density ($\geq$ 10$^{7}$ cm$^{-3}$), tempera…
The deuterium fractionation of water can serve as a tracer for the chemical and physical evolution of water during star formation and can constrain the origin of water in Solar System bodies. We determine the HDO/H$_2$O ratio in the inner warm gas toward three low-mass Class 0 protostars selected to be in isolated cores, i.e., not associated with any cloud complexes. Previous sources for which the HDO/H$_2$O ratio have been established were all part of larger star-forming complexes. Targeting these isolated protostars allows comparison of the water chemistry in isolated and clustered regions t…
Context: Despite the low elemental deuterium abundance in the Galaxy, enhanced molecular D/H ratios have been found in the environments of low-mass star-forming regions and, in particular, the Class 0 protostar IRAS 16293-2422. Aims: The key program Chemical HErschel Surveys of Star forming regions (CHESS) aims at studying the molecular complexity of the interstellar medium. The high sensitivity and spectral resolution of the Herschel/HIFI instrument provide a unique opportunity to observe the fundamental 1_{1,1}-0_{0,0} transition of ortho-D2O at 607 GHz and the higher energy 2_{1,2}-1_{0,1} …
(abridged) Data and results from the WISH key program are summarized, designed to provide a legacy data set to address its physics and chemistry. WISH targeted ~80 sources along the two axes of luminosity and evolutionary stage: from low- to high-mass protostars and from pre-stellar cores to protoplanetary disks. Lines of H2O, HDO, OH, CO and [O I] were observed with the HIFI and PACS instruments, complemented by molecules that probe UV, X-ray or grain chemistry. Most of the far-infrared water emission from protostars is found to be compact, originating from warm outflowing and shocked gas at …
We study the composition of the faint radio population selected from the VLA-COSMOS 3GHz Large Project, a radio continuum survey performed at 10 cm wavelength. The survey covers the full 2 square degree COSMOS field with mean $rms\sim2.3$ $μ$Jy/beam, cataloging 10,899 source components above $5\times rms$. By combining these radio data with UltraVISTA, optical, near-infrared, and Spitzer/IRAC mid-infrared data, as well as X-ray data from the Chandra Legacy, and Chandra COSMOS surveys, we gain insight into the emission mechanisms within our radio sources out to redshifts of $z\sim5$. From these…
The relative abundances of singly-deuterated methanol isotopologues, [CH$_{2}$DOH]/[CH$_{3}$OD], in star-forming regions deviate from the statistically expected ratio of 3. In Orion KL, the nearest high-mass star-forming region to Earth, the singly-deuterated methanol ratio is about 1, and the cause for this observation has been explored through theory for nearly three decades. We present high-angular resolution observations of Orion KL using the Atacama Large Millimeter/submillimeter Array to map small-scale changes in CH$_{3}$OD column density across the nebula, which provide a new avenue to…
We present results on the excitation properties of z~2.3 galaxies using early observations from the MOSFIRE Deep Evolution Field (MOSDEF) Survey. With its coverage of the full suite of strong rest-frame optical emission lines, MOSDEF provides an unprecedented view of the rest-frame optical spectra of a representative sample of distant star-forming galaxies. We investigate the locations of z~2.3 MOSDEF galaxies in multiple emission-line diagnostic diagrams. These include the [OIII]/Hb vs. [NII]/Ha and [OIII]/Hb vs. [SII]/Ha "BPT" diagrams, as well as the O_32 vs. R_23 excitation diagram. We rec…
We investigate the structure of the interstellar medium (ISM) and identify the location of possible embedded excitation sources from far-infrared (FIR) line and mid-infrared continuum emission maps. We carried out imaging spectroscopic observations of four giant Galactic star-forming regions with the Fourier Transform Spectrometer (FTS) onboard AKARI. We obtained [OIII] 88 micron and [CII] 158 micron line intensity maps of all the regions: G3.270-0.101, G333.6-0.2, NGC3603, and M17. For G3.270-0.101, we obtained high-spatial-resolution [OIII] 88 micron line-emission maps and a FIR continuum ma…
We utilize medium-resolution JWST/NIRSpec observations of 164 galaxies at $z=2.0-9.3$ from the Cosmic Evolution Early Release Science (CEERS) survey to investigate the evolution of the excitation and ionization properties of galaxies at high redshifts. Our results represent the first statistical constraints on the evolution of the [OIII]/H$β$ vs. [NII]/H$α$, [SII]/H$α$, and [OI]/H$α$ ``BPT'' diagrams at $z>2.7$, and the first analysis of the O32 vs. R23 diagram at $z>4$ with a large sample. We divide the sample into five redshift bins containing 30-40 galaxies each. The subsamples at $z\sim2.3…
We present CO(1-0) observations obtained at the Karl G. Jansky Very Large Array (VLA) for 14 z~2 galaxies with existing CO(3-2) measurements, including 11 galaxies which contain active galactic nuclei (AGN) and three submillimeter galaxies (SMGs). We combine this sample with an additional 15 z~2 galaxies from the literature that have both CO(1-0) and CO(3-2) measurements in order to evaluate differences in CO excitation between SMGs and AGN host galaxies, measure the effects of CO excitation on the derived molecular gas properties of these populations, and to look for correlations between the …
We investigate the CO excitation and interstellar medium (ISM) conditions in a cold gas mass-selected sample of 22 star-forming galaxies at $z=0.46-3.60$, observed as part of the ALMA Spectroscopic Survey in the Hubble Ultra Deep Field (ASPECS). Combined with VLA follow-up observations, we detect a total of 34 CO $J \rightarrow J-1$ transitions with $J=1$ up to $8$ (and an additional 21 upper limits, up to $J=10$) and six [C I] ${^3P}_1 \rightarrow {^3P}_0$ and ${^3P}_2 \rightarrow {^3P}_1$ transitions (and 12 upper limits). The CO(2-1) and CO(3-2)-selected galaxies, at $z=1.2$ and $2.5$, resp…
Herschel/HIFI observations toward the compact HII region W51 has revealed the presence of a cold dense core along its line of sight in a high-velocity stream located just in front of W51. This detection has been made possible through absorption measurements of low-energy transitions of HDO, NH3, and C3 against the bright background emitted by the star-forming region. We present a follow-up study of this core using the high sensitivity and high spectral resolution provided by the IRAM 30-meter telescope. We report new detections of this core in absorption for DCO+ (2-1, 3-2), H13CO+ (1-0), DNC …
The object W33 is a giant molecular cloud that contains star forming regions at various evolutionary stages from quiescent clumps to developed H II regions. Since its star forming regions are located at the same distance and the primary material of the birth clouds is probably similar, we conducted a comparative chemical study to trace the chemical footprint of the different phases of evolution. We observed six clumps in W33 with the Atacama Pathfinder Experiment (APEX) telescope at 280 GHz and the Submillimeter Array (SMA) at 230 GHz. We detected 27 transitions of 10 different molecules in th…
When Jets Don't Quench: Near-Infrared H$_{2}$ in Star Forming Low-Excitation Radio Galaxies
Johns Hopkins University（约翰斯·霍普金斯大学）；Space Telescope Science Institute（太空望远镜科学研究所）；University of California, Santa Cruz（加州大学圣克鲁兹分校）；Jet Propulsion Laboratory, California Institute of Technology（加州理工学院喷气推进实验室）；National Radio Astronomy Observatory（国家射电天文台）；Université de la Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange（蔚蓝海岸大学、蔚蓝海岸天文台、法国国家科学研究中心拉格朗日实验室）；AURA for ESA, Space Telescope Science Institute（欧洲空间局下属美国大学研究协会太空望远镜科学研究所）；University of California, Davis（加州大学戴维斯分校）
We investigate the physical conditions of ionized gas in high-z star-forming galaxies using diagnostic diagrams based on the rest-frame optical emission lines. The sample consists of 701 galaxies with an Ha detection at $1.4\lesssim z\lesssim1.7$, from the FMOS-COSMOS survey, that represent the normal star-forming population over the stellar mass range $10^{9.6} \lesssim M_\ast/M_\odot \lesssim 10^{11.6}$ with those at $M_\ast>10^{11}~M_\odot$ being well sampled. We confirm an offset of the average location of star-forming galaxies in the BPT diagram ([OIII]/Hb vs. [NII]/Ha), primarily towards…
We present a systematic survey of multiple velocity-resolved H$_2$O spectra using Herschel/HIFI towards nine nearby actively star forming galaxies. The ground-state and low-excitation lines (E$_{\rm up}\,\le 130\,{\rm K}$) show profiles with emission and absorption blended together, while absorption-free medium-excitation lines ($130\,{\rm K}\, \le\, E_{\rm up}\,\le\,350\,{\rm K}$) typically display line shapes similar to CO. We analyze the HIFI observation together with archival SPIRE/PACS H$_2$O data using a state-of-the-art 3D radiative transfer code which includes the interaction between c…
The emission-line intensity ratios are used to distinguish the main sources of gas ionization to study the state of galactic interstellar medium (ISM). In intermediate cases, when the contributions of radiation from some sources mix, the identification becomes uncertain. As an extra parameter, the gas velocity dispersion in the line-of-sight can be added to classical diagnostic diagrams (i.e., "BPT-sigma" relations) to help finding an appropriate solution. The minimum distance from the curve that bounds the H II-type ionization region for each point in BPT-sigma diagram can be used to characte…
Theoretical models suggest that massive stars form via disk-mediated accretion, with bipolar outflows playing a fundamental role. A recent study toward massive molecular outflows has revealed a decrease of the SiO line intensity as the object evolves. The present study aims at characterizing the variation of the molecular outflow properties with time, and at studying the SiO excitation conditions in outflows associated with massive YSOs. We used the IRAM30m telescope to map 14 massive star-forming regions in the SiO(2-1), SiO(5-4) and HCO+(1-0) outflow lines, and in several dense gas and hot c…
We study the relationship between stellar mass, star formation rate (SFR),ionization state, and gas-phase metallicity for a sample of 41 normal star-forming galaxies at $3 \lesssim z \lesssim 3.7$. The gas-phase oxygen abundance, ionization parameter, and electron density of ionized gas are derived from rest-frame optical strong emission lines measured on near-infrared spectra obtained with Keck/MOSFIRE. We remove the effect of these strong emission lines in the broad-band fluxes to compute stellar masses via spectral energy distribution fitting, while the SFR is derived from the dust-correcte…
The goal of this paper is to study the spatial distribution of HNCO in massive star-forming regions, and investigate its spatial association with infrared sources, as well as physical conditions in region of HNCO emission. We have mapped nine massive star-forming regions in HNCO 5$_{05}-4_{04}$ with the Purple Mountain Observatory 13.7m telescope. The C18O maps of these sources were obtained simultaneously. The HNCO emission shows compact distribution, with emission peak centred on water masers. Nearly all the HNCO clumps show signs of embedded mid-infrared or far-infrared sources. The FWHM si…
Common Excitation Patterns of Star Formation, Active Galactic Nuclei, and Shocks in Seyfert Galaxies
Smithsonian Astrophysical Observatory（史密森尼天体物理台）；Research School of Astronomy and Astrophysics, Australian National University（澳大利亚国立大学天文与天体物理研究学院）；Astronomical Observatory of the Jagiellonian University（雅盖隆大学天文台）；NASA-Goddard Space Flight Center（NASA戈达德太空飞行中心）；INAF Osservatorio Astronomico di Roma（意大利国家天体物理研究所罗马天文台）
We present observations of HCO+ and H^13CO+, N2H+, HCS+, HCN and HN^13C, SO and ^34SO, CCH, SO_2, and CH_3OH-E towards a sample of 27 high-mass clumps coincident with water maser emission. All transitions are observed with or convolved to nearly identical resolution (30"), allowing for inter-comparison of the clump properties derived from the mapped transitions. We find N2H+ emission is spatially differentiated compared to the dust and the other molecules towards a few very luminous cores (10 of 27) and the N2H+ integrated intensity does not correlate well with dust continuum flux. We calculat…
We have examined polycyclic aromatic hydrocarbon (PAH) excitation in a sample of 25 nearby face-on spiral galaxies using the ratio of mid-infrared PAH emission to dust mass. Within 11 of the galaxies, we found that the PAH excitation was straightforwardly linked to ultraviolet or mid-infrared star formation tracers, which, along with other results studying the relation of PAH emission to star formation, indicates that the PAHs are most strongly excited in dusty shells around the star forming regions. Within another 5 galaxies, the PAH emission is enhanced around star forming regions only at sp…
Only recently, OD, the deuterated isotopolog of hydroxyl, OH, has become accessible in the interstellar medium; spectral lines from both species have been observed in the supra-Terahertz and far infrared regime. Here we study rotational lines of OD and OH towards 13 Galactic high-mass star forming regions, with the aim to constrain the OD abundance and infer the deuterium fractionation of OH in their molecular envelopes. We used the Stratospheric Observatory for Infrared Astronomy (SOFIA) to observe the $^2Π_{3/2}$ $J=5/2-3/2$ ground-state transition of OD at 1.3 THz ($215~μ$m) and the rotatio…
Phosphorus nitride (PN) is the P-bearing species with the highest number of detections in star-forming regions. Multi-line studies of the molecule have shown that the excitation temperature of PN is usually lower than the gas kinetic temperature, suggesting that PN is likely in conditions of sub-thermal excitation. We present an analysis of PN which takes the possible sub-thermal excitation conditions into account in a sample of 24 massive star-forming regions. We observed PN (2-1), (3-2), (4-3), and (6-5) with the IRAM-30m and APEX telescopes and detected PN lines in 15 of them. Together with…
We present spectrally resolved observations of triatomic carbon (C3) in several ro-vibrational transitions between the vibrational ground state and the low-energy nu2 bending mode at frequencies between 1654-1897 GHz along the sight-lines to the submillimeter continuum sources W31C and W49N, using Herschel's HIFI instrument. We detect C3 in absorption arising from the warm envelope surrounding the hot core, as indicated by the velocity peak position and shape of the line profile. The sensitivity does not allow to detect C3 absorption due to diffuse foreground clouds. From the column densities …
Observations of molecular gas in high-z star-forming galaxies typically rely on emission from CO lines arising from states with rotational quantum numbers J > 1. Converting these observations to an estimate of the CO J=1-0 intensity, and thus inferring H2 gas masses, requires knowledge of the CO excitation ladder, or spectral line energy distribution (SLED). The few available multi-J CO observations of galaxies show a very broad range of SLEDs, even at fixed galaxy mass and star formation rate, making the conversion to J=1-0 emission and hence molecular gas mass highly uncertain. Here, we comb…
We present VLT/SINFONI near-infrared (NIR) integral field spectroscopy of six $z \sim 0.2$ Lyman break galaxy "analogs" (LBAs), from which we detect HI, HeI, and [FeII] recombination lines, and multiple H$_2$ ro-vibrational lines in emission. Pa$α$ kinematics reveal high velocity dispersions and low rotational velocities relative to random motions ($\langle v/σ\rangle = 1.2 \pm 0.8$). Matched-aperture comparisons of H$β$, H$α$, and Pa$α$ reveal that the nebular color excesses are lower relative to the continuum color excesses than is the case for typical local star-forming systems. We compare …
We demonstrate the feasibility and potential of using large integral field spectroscopic surveys to investigate the prevalence of galactic-scale outflows in the local Universe. Using integral field data from SAMI and the Wide Field Spectrograph, we study the nature of an isolated disk galaxy, SDSS J090005.05+000446.7 (z = 0.05386). In the integral field datasets, the galaxy presents skewed line profiles changing with position in the galaxy. The skewed line profiles are caused by different kinematic components overlapping in the line-of-sight direction. We perform spectral decomposition to sepa…
We investigate the CO excitation of normal star forming disk galaxies at z=1.5 using IRAM PdBI observations of the CO[2-1], CO[3-2] and CO[5-4] transitions for 4 galaxies, including VLA observations of CO[1-0] for 3 of them, with the aim of constraining the average state of H2 gas. Exploiting prior knowledge of the velocity range, spatial extent and size of the CO emission we measure reliable line fluxes with S/N>4-7 for individual transitions. While the average CO Spectral Line Energy Distribution (SLED) has a sub-thermal excitation similar to the Milky Way (MW) up to CO[3-2], we show that th…
We present a detailed study of the rest-optical (3600-7000 Angstrom) nebular spectra of ~380 star-forming galaxies at z~2-3 obtained with Keck/MOSFIRE as part of the Keck Baryonic Structure Survey (KBSS). The KBSS-MOSFIRE sample is representative of star-forming galaxies at these redshifts, with stellar masses M*=10^9-10^11.5 M_sun and star formation rates SFR=3-1000 M_sun/yr. We focus on robust measurements of many strong diagnostic emission lines for individual galaxies: [O II]3727,3729, [Ne III]3869, H-beta, [O III]4960,5008, [N II]6549,6585, H-alpha, and [S II]6718,6732. Comparisons with o…
In the framework of the Herschel/PRISMAS Guaranteed Time Key Program, the line of sight to the distant ultracompact HII region W51e2 has been observed using several selected molecular species. Most of the detected absorption features are not associated with the background high-mass star-forming region and probe the diffuse matter along the line of sight. We present here the detection of an additional narrow absorption feature at ~70 km/s in the observed spectra of HDO, NH3 and C3. The 70 km/s feature is not uniquely identifiable with the dynamic components (the main cloud and the large-scale f…
We present the first results of the unbiased survey of the L1157-B1 bow shock, obtained with HIFI in the framework of the key program Chemical Herschel surveys of star forming regions (CHESS). The L1157 outflow is driven by a low-mass Class 0 protostar and is considered the prototype of the so-called chemically active outflows. The bright blue-shifted bow shock B1 is the ideal laboratory for studying the link between the hot (around 1000-2000 K) component traced by H2 IR-emission and the cold (around 10-20 K) swept-up material. The main aim is to trace the warm gas chemically enriched by the p…
The relative populations in rotational transitions of CO can be useful for inferring gas conditions and excitation mechanisms at work in the interstellar medium. We present CO emission lines from rotational transitions observed with Herschel/HIFI in the star-forming cores Orion S, Orion KL, Sgr B2(M), and W49N. Integrated line fluxes from these observations are combined with those from Herschel/PACS observations of the same sources to construct CO spectral line energy distributions (SLEDs) from $5\leq J_u\leq48$. These CO SLEDs are compared to those reported in other galaxies, with the intenti…
We study the interstellar medium (ISM) properties as a function of the molecular gas size for 77 infrared-selected galaxies at $z \sim 1.3$. Molecular gas sizes are measured on ALMA images that combine CO(2-1), CO(5-4) and underlying continuum observations, and include CO(4-3), CO(7-6)+[CI]($^3 P_2-^3P_1$), [CI]($^3 P_1-^3P_0$) observations for a subset of the sample. The $\gtrsim 46 \%$ of our galaxies have a compact molecular gas reservoir, and lie below the optical disks mass-size relation. Compact galaxies on and above the main sequence have higher CO excitation and star formation efficien…
We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of high-J CO lines ($J_\mathrm{up}=6$, 7, 8) and associated dust continuum towards five strongly lensed, dusty, star-forming galaxies (DSFGs) at redshift $z = 2.7$-5.7. These galaxies, discovered in the South Pole Telescope survey, are observed at $0.2''$-$0.4''$ resolution with ALMA. Our high-resolution imaging coupled with the lensing magnification provides a measurement of the structure and kinematics of molecular gas in the background galaxies with spatial resolutions down to kiloparsec scales. We derive visibility…
The AURORA Survey: Determining the Production Mechanism for OI $\mathbf{λ8449}$ Emission in Star-forming Galaxies at Cosmic Noon
University of California, Los Angeles（加州大学洛杉矶分校）；Shanghai Jiao Tong University（上海交通大学）；University of Kentucky（肯塔基大学）；University of California, Riverside（加州大学河滨分校）；University of California, Davis（加州大学戴维斯分校）；University of Chicago（芝加哥大学）；Kavli Institute for Cosmological Physics, University of Chicago（卡弗里宇宙物理学研究所，芝加哥大学）
One of the key questions in observational cosmology is the identification of the sources responsible for ionisation of the Universe after the cosmic Dark Ages, when the baryonic matter was neutral. The currently identified distant galaxies are insufficient to fully reionise the Universe by redshift z~6, but low-mass star-forming galaxies are thought to be responsible for the bulk of the ionising radiation. Since direct observations at high redshift are difficult for a variety of reasons, one solution is to identify local proxies of this galaxy population. However, starburst galaxies at low red…
Brightest Cluster Galaxies (BCGs) are typically massive ellipticals at the centers of clusters. They are believed to experience strong environmental processing, and their mass assembly and star formation history are still debated. We have selected three star forming BCGs in the equatorial field of the Kilo-Degree Survey (KiDS) at intermediate redshifts. We have observed them with the IRAM-30m telescope in the first three CO transitions. We remarkably detected all BCGs at high signal-to-noise ratio ${\rm S/N}\simeq(3.8-10.2)$, for a total of 7 detected lines out of 8, corresponding to a success…
Interstellar chemistry in low metallicity environments is crucial to understand chemical processes in the past metal-poor universe. Recent studies of interstellar molecules in nearby low-metallicity galaxies have suggested that the metallicity has a significant effect on chemistry of star-forming cores. Here we report the first detection of a hot molecular core in the extreme outer Galaxy, which is an excellent laboratory to study star formation and interstellar medium in a Galactic low-metallicity environment. The target star-forming region, WB89-789, is located at the galactocentric distance…
