We present the first results on the diffuse transition clouds observed in [CII] line emission at 158 microns (1.9 THz) towards Galactic longitudes near 340deg (5 LOSs) and 20deg (11 LOSs) as part of the GOT C+ survey. Out of the total 146 [CII] velocity components detected by profile fitting we identify 53 as diffuse molecular clouds with associated $^{12}$CO emission but without $^{13}$CO emission and characterized by A$_V$ < 5 mag. We estimate the fraction of the [CII] emission in the diffuse HI layer in each cloud and then determine the [CII] emitted from the molecular layers in the cloud. We show that the excess [CII] intensities detected in a few clouds is indicative of a thick H$_2$ layer around the CO core. The wide range of clouds in our sample with thin to thick H$_2$ layers suggests that these are at various evolutionary states characterized by the formation of H$_2$ and CO layers from HI and C$^+$, respectively. In about 30% of the clouds the H$_2$ column densities (''dark gas'') traced by the [CII] is 50% or more than that traced by $^{12}$CO emission. On the average about 25% of the total H$_2$ in these clouds is in an H$_2$ layer which is not traced by CO. We use the HI, [CII], and $^{12}$CO intensities in each cloud along with simple chemical models to obtain constraints on the FUV fields and cosmic ray ionization rates.
Aims: To investigate properties of [CII]158 $μ$m emission of RCW36 in a dense filamentary cloud. Methods: [CII] observations of RCW36 covering an area of ~30 arcmin$\times$30 arcmin were carried out with a Fabry-Pérot spectrometer aboard a 100-cm balloon-borne far-infrared (IR) telescope with an angular resolution of 90 arcsec. By using AKARI and Herschel images, the spatial distribution of the [CII] intensity was compared with those of emission from the large grains and PAH. Results: The [CII] emission is spatially in good agreement with shell-like structures of a bipolar lobe observed in IR …
The [CII] fine--structure line at 158um is an excellent tracer of the warm diffuse gas in the ISM and the interfaces between molecular clouds and their surrounding atomic and ionized envelopes. Here we present the initial results from Galactic Observations of Terahertz C+ (GOTC+), a Herschel Key Project devoted to study the [CII] fine structure emission in the galactic plane using the HIFI instrument. We use the [CII] emission together with observations of CO as a probe to understand the effects of newly--formed stars on their interstellar environment and characterize the physical and chemical…
We present observations of velocity-resolved [CII] 158 $μ$m emission from both a dense and a more diffuse photodissociation region (PDR) in the Perseus giant molecular cloud (GMC) using the Heterodyne Instrument for the Far-Infrared onboard the Herschel Space Telescope. We detect [CII] emission from 80\% of the total positions, with a 95\% detection rate from the dense boundary region. The integrated intensity of the [CII] emission remains relatively constant across each boundary, despite the observed range in optical extinction between 1 mag and 10 mag. This flat profile indicates a constant …
Observations of ionised carbon at 158 micron ([CII]) from luminous star-forming galaxies at z~0 show that their ratios of [CII] to far infrared (FIR) luminosity are systematically lower than those of more modestly star-forming galaxies. In this paper, we provide a theory for the origin of this so called "[CII] deficit" in galaxies. Our model treats the interstellar medium as a collection of clouds with radially-stratified chemical and thermal properties, which are dictated by the clouds' volume and surface densities, as well as the interstellar radiation and cosmic ray fields to which they are…
Our understanding of how molecular clouds form in the interstellar medium (ISM) would be greatly helped if we had a reliable observational tracer of the gas flows responsible for forming the clouds. Fine structure emission from singly ionised and neutral carbon ([CII], [CI]) and rotational line emission from CO are all observed to be associated with molecular clouds. However, it remains unclear whether any of these tracers can be used to study the inflow of gas onto an assembling cloud, or whether they primarily trace the cloud once it has already assembled. In this paper, we address this issu…
Observations towards L1630 in the Orion B molecular cloud, comprising the iconic Horsehead Nebula, allow us to study the interplay between stellar radiation and a molecular cloud under relatively benign conditions, that is, intermediate densities and an intermediate UV radiation field. Contrary to the well-studied Orion Molecular Cloud 1 (OMC1), which hosts much harsher conditions, L1630 has little star formation. We aim to relate the [CII] fine-structure line emission to the physical conditions predominant in L1630 and compare it to studies of OMC1. The [CII] $158\,μ\mathrm{m}$ emission from …
We report a tentative correlation between the outflow characteristics derived from OH absorption at $119\,μ\text{m}$ and [CII] emission at $158\,μ\text{m}$ in a sample of 22 local and bright ultraluminous infrared galaxies (ULIRGs). For this sample we investigate whether [CII] broad wings are a good tracer of molecular outflows, and how the two tracers are connected. Fourteen objects in our sample have a broad wing component as traced by [CII], and all of these also show OH119 absorption indicative of an outflow (in 1 case an inflow). The other eight cases, where no broad [CII] component was f…
We present new observations of [CII] fine structure line emission from an isolated molecular cloud using the upGREAT instrument onboard SOFIA. These data are analyzed together with archival CO=1-0 and HI 21 cm emission spectra to investigate the role of converging atomic gas flows in the formation of molecular clouds. Bright [CII] emission is detected throughout the mapped area that likely originates from photodissociation regions excited by UV radiation fields produced by newborn stars within the cloud. Upon spatial averaging of the [CII] spectra, we identify weak [CII] emission within veloci…
We present the [CII] 157.7 micron map of galaxy NGC 7331 obtained with FIFI-LS on SOFIA. This map extends an existent Herschel/PACS observation of the central strip of the galaxy to encompass the entire molecular ring and much of the disk, including multiple spiral arms with intense far-IR emission. We also present Herschel archival data of the [NII] 205 micron line which covers a substantial part of the [CII] SOFIA observations and allows us to estimate the neutral fraction of the [CII] emission along the ring and disk of the galaxy. We find that the neutral fraction rises with the distance f…
We present the first 7.5'x11.5' velocity-resolved map of the [CII]158um line toward the Orion molecular cloud-1 (OMC-1) taken with the Herschel/HIFI instrument. In combination with far-infrared (FIR) photometric images and velocity-resolved maps of the H41alpha hydrogen recombination and CO J=2-1 lines, this data set provides an unprecedented view of the intricate small-scale kinematics of the ionized/PDR/molecular gas interfaces and of the radiative feedback from massive stars. The main contribution to the [CII] luminosity (~85%) is from the extended, FUV-illuminated face of the cloud G_0>500…
The molecular gas content of normal galaxies at z>4 is poorly constrained, because the commonly used molecular gas tracers become hard to detect. We use the [CII]158um luminosity, recently proposed as a molecular gas tracer, to estimate the molecular gas content in a large sample of main-sequence star-forming galaxies at z=4.4-5.9, with a median stellar mass of 10^9.7 Msun, drawn from the ALMA Large Program to INvestigate [CII] at Early times (ALPINE) survey. The agreement between molecular gas masses derived from [CII] luminosity, dynamical mass, and rest-frame 850um luminosity, extrapolated …
We present the first results of the Herschel open time key program, Galactic Observations of Terahertz C$^+$ (GOT C+) survey of the [CII] fine-structure line at 1.9 THz (158 microns) using the HIFI instrument on Herschel. We detected 146 interstellar clouds along sixteen lines-of-sight towards the inner Galaxy. We also acquired HI and CO isotopologue data along each line-of-sight for analysis of the physical conditions in these clouds. Here we analyze 29 diffuse clouds (A$_{V}$ < 1.3 mag.) in this sample characterized by having [CII] and HI emission, but no detectable CO. We find that [CII] em…
The spiral arm tangencies are ideal lines of sight in which to determine the distribution of interstellar gas components in the spiral arms and study the influence of spiral density waves on the interarm gas in the Milky Way. We present a large scale (~15deg) position-velocity map of the Galactic plane in [CII] from l = 326.6 to 341.4deg observed with Herschel HIFI. We use [CII] l-v maps along with those for Hi and 12CO to derive the average spectral line intensity profiles over the longitudinal range of each tangency. Using the VLSR of the emission features, we locate the [CII], HI, and 12CO …
We analyze the collisional excitation of the 158 micron (1900.5 GHz) fine structure transition of ionized carbon (C+) in terms of line intensities produced by simple cloud models. The single C+ fine structure transition is a very important coolant of the atomic interstellar medium and of photon dominated regions in which carbon is partially or completely in ionized form. The [CII] line is widely used as a tracer of star formation in the Milky Way and other galaxies. Excitation of the [CII] fine structure transition can be via collisions with hydrogen molecules, atoms, and electrons. Velocity-r…
We present SÍGAME simulations of the [CII]157.7$μ$ fine structure line emission from cosmological smoothed particle hydrodynamics (SPH) simulations of seven main sequence galaxies at z=2. Using sub-grid physics prescriptions the gas in our simulations is modeled as a multi-phased interstellar medium (ISM) comprised of molecular gas residing in giant molecular clouds, an atomic gas phase associated with photo-dissociation regions (PDRs) at the cloud surfaces, and a diffuse, ionized gas phase. Adopting logotropic cloud density profiles and accounting for heating by the local FUV radiation field …
The [CII]158um line is one of the dominant cooling lines in star-forming active regions. The commonly assumed clumpy UV-penetrated cloud models predict a [CII] line profile similar to that of CO. However, recent spectral-resolved observations show that they are often very different, indicating a more complex origin of the line emission including the dynamics of the source region. The aim of our study is to investigate the physical properties of the star-forming ISM in the Large Magellanic Cloud (LMC) by separating the origin of the emission lines spatially and spectrally. In this paper, we foc…
The aim of our study is to investigate the physical properties of the star-forming interstellar medium (ISM) in the Large Magellanic Cloud (LMC) by separating the origin of the emission lines spatially and spectrally. Following Okada et al. (2015, Paper I), we investigate different phases of the ISM traced by carbon-bearing species in four star-forming regions in the LMC, and model the physical properties using the KOSMA-tau PDR model. We mapped 3--13 arcmin$^2$ areas in 30 Dor, N158, N160 and N159 along the molecular ridge of the LMC in [CII]158um with GREAT on board SOFIA, and in CO(2-1) to …
The distribution of various interstellar gas components and the pressure in the interstellar medium (ISM) is a result of the interplay of different dynamical mechanisms and energy sources on the gas in the Milky Way. The scale heights of the different gas tracers, such as HI and CO, are a measure of these processes. The scale height of [CII] emission in the Galactic plane is important for understanding those ISM components not traced by CO or HI. We determine the average distribution of [CII] perpendicular to the plane in the inner Galactic disk and compare it to the distributions of other key…
We present SOFIA/FIFI-LS observations of the [CII] 158$μ$m cooling line across the nearby spiral galaxy NGC 6946. We combine these with UV, IR, CO, and H I data to compare [CII] emission to dust properties, star formation rate (SFR), H$_2$, and HI at 560pc scales via stacking by environment (spiral arms, interarm, and center), radial profiles, and individual, beam-sized measurements. We attribute $73\%$ of the [CII] luminosity to arms, and $19\%$ and $8\%$ to the center and interarm region, respectively. [CII]/TIR, [CII]/CO, and [CII]/PAH radial profiles are largely constant, but rise at large…
We aim to understand the contribution of the ionized, atomic and molecular phases of the ISM to the [CII] emission from clouds near the dynamical center and the BCLMP302 HII region in the north of the nearby galaxy M33 at a spatial resolution of 50pc. We combine high resolution [CII] spectra taken with the HIFI spectrometer onboard the Herschel satellite with [CII] Herschel-PACS maps and ground-based observations of CO(2-1) and HI. All data are at a common spatial resolution of 50pc. Typically, the [CII] lines have widths intermediate between the narrower CO(2-1) and broader HI line profiles. …
This paper presents [CII], [CI] and CO emission line maps of the star-forming regions N66, N25+N26, and N88 in the metal-poor Local Group dwarf galaxy SMC. The spatial and velocity structure of the large HII region N66 reveals an expanding ring of shocked molecular gas centered on the exciting star cluster NGC346, whereas a more distant dense molecular cloud is being eroded by UV radiation from the same cluster. In the N25+N26 and N88 maps, diffuse [CII] emission at a relatively low surface brightness extends well beyond the compact boundaries of the bright emission associated with the [CII] r…
The advent of new sub-millimeter observational facilities has stimulated the desire to model the sub-mm line emission of galaxies within cosmological galaxy formation models. This is typically done in post-processing by applying sub-resolution recipes to describe the properties of the unresolved interstellar medium. At the same time, while there is freedom in how one implements these sorts of recipes, the impact of various choices has yet to be systematically explored in simulations. In this paper, we do just that. We combine a semi-analytic model of galaxy formation with chemical equilibrium …
We determine the source of the diffuse [CII] emission by studying its spatial (radial and vertical) distributions. We used the HIFI [CII] Galactic survey (GOT C+), along with HI, 12CO, and 13CO data toward 354 lines of sight, and several HIFI [CII] and [CI] position-velocity maps. We quantified the emission in each spectral line profile by evaluating the intensities in 3 km/s wide velocity bins, 'spaxels'. Using the detection of [CII] with CO or [CI], we separated the dense and diffuse gas components. We derived 2-D Galactic disk maps using the spaxel velocities for kinematic distances. We sep…
Revealing the 3D dynamics of HII regions and their associated molecular clouds is important for understanding the longstanding problem as to how stellar feedback affects the density structure and kinematics of the interstellar medium. We employed observations of the HII region RCW 120 in [CII], observed within the SOFIA legacy program FEEDBACK, and the $^{12}$CO and $^{13}$CO (3$\to$2) lines, obtained with APEX. In addition we used HI data from the Southern Galactic Plane Survey. Two radiative transfer models were used to fit the observed data. A line profile analysis with the 1D non-LTE radia…
We present and analyze deep Herschel/HIFI observations of the [CII] 158um, [CI] 609um, and [CI] 370um lines towards 54 lines-of-sight (LOS) in the Large and Small Magellanic clouds. These observations are used to determine the physical conditions of the line--emitting gas, which we use to study the transition from atomic to molecular gas and from C^+ to C^0 to CO in their low metallicity environments. We trace gas with molecular fractions in the range 0.1<f(H2)<1, between those in the diffuse H2 gas detected by UV absorption (f(H2)<0.2) and well shielded regions in which hydrogen is essentiall…
The C$^{+}$ ion is an important coolant of interstellar gas, and so the [CII] fine structure line is frequently observed in the interstellar medium. However, the physical and chemical properties of the [CII]-emitting gas are still unclear. We carry out non-LTE radiative transfer simulations with RADMC-3D to study the [CII] line emission from a young, turbulent molecular cloud before the onset of star formation, using data from the SILCC-Zoom project. The [CII] emission is optically thick over 40% of the observable area with $I_{[\textrm{CII}]} > 0.5$ K km s$^{-1}$. To determine the physical pr…
The Small Magellanic Cloud (SMC) provides the only laboratory to study the structure of molecular gas at high resolution and low metallicity. We present results from the Herschel Spectroscopic Survey of the SMC (HS$^{3}$), which mapped the key far-IR cooling lines [CII], [OI], [NII], and [OIII] in five star-forming regions, and new ALMA 7m-array maps of $^{12}$CO and $^{13}$CO $(2-1)$ with coverage overlapping four of the five HS$^{3}$ regions. We detect [CII] and [OI] throughout all of the regions mapped. The data allow us to compare the structure of the molecular clouds and surrounding photo…
We present Herschel, ALMA, and MUSE observations of the molecular ring of Messier 104, also known as the Sombrero galaxy. These previously unpublished archival data shed new light on the content of the interstellar medium of M104. In particular, molecular hydrogen measured by CO emission and dust measured by far-infrared light are uniformly distributed along the ring. The ionized gas revealed by H$α$ and [CII] emission is distributed in knots along the ring. Despite being classified as an SAa galaxy, M104 displays features typical of early-type galaxies. We therefore compared its [CII] and dus…
The [CII] 158$μ$m emission line can arise in all phases of the ISM, therefore being able to disentangle the different contributions is an important yet unresolved problem when undertaking galaxy-wide, integrated [CII] observations. We present a new multi-phase 3D radiative transfer interface that couples Starburst99, a stellar spectrophotometric code, with the photoionisation and astrochemistry codes Mocassin and 3D-PDR. We model entire star forming regions, including the ionised, atomic and molecular phases of the ISM, and apply a Bayesian inference methodology to parametrise how the fraction…
Of the almost 40 star forming galaxies at z>~5 (not counting QSOs) observed in [CII] to date, nearly half are either very faint in [CII], or not detected at all, and fall well below expectations based on locally derived relations between star formation rate (SFR) and [CII] luminosity. Combining cosmological zoom simulations of galaxies with SIGAME (SImulator of GAlaxy Millimeter/submillimeter Emission) we have modeled the multi-phased interstellar medium (ISM) and its emission in [CII], [OI] and [OIII], from 30 main sequence galaxies at z~6 with star formation rates ~3-23Msun/yr, stellar masse…
We present SOFIA-upGREAT observations of [CII] emission of Infrared Dark Cloud (IRDC) G035.39-00.33, designed to trace its atomic gas envelope and thus test models of the origins of such clouds. Several velocity components of [CII] emission are detected, tracing structures that are at a wide range of distances in the Galactic plane. We find a main component that is likely associated with the IRDC and its immediate surroundings. This strongest emission component has a velocity similar to that of the $^{13}$CO(2-1) emission of the IRDC, but offset by $\sim3\:{\rm km\:s}^{-1}$ and with a larger v…
While the CO(1-0) transition is often used to deduce the total molecular hydrogen in galaxies, it is challenging to detect in low metallicity galaxies, in spite of the star formation taking place. In contrast, the [CII] 158 micron line is relatively bright, highlighting a potentially important reservoir of H2 that is not traced by CO(1-0), but residing in the C+ - emitting regions. We explore a method to quantify the total H2 mass (MH2) in galaxies and learn what parameters control the CO-dark gas reservoir. We present Cloudy grids of density, radiation field and metallicity in terms of observ…
Context. The [CII] 158micron far-infrared fine-structure line is one of the dominant cooling lines of the star-forming interstellar medium (ISM). Hence [CII] emission originates in and thus can be used to trace a range of ISM processes. Velocity-resolved large-scale mapping of [CII] in star-forming regions provides a unique perspective of the kinematics of these regions and their interactions with the exciting source of radiation. Aims. We explore the scientific applications of large-scale mapping of velocity-resolved [CII] observations. With the [CII] observations, we investigate the effect o…
We investigate the fine-structure [C${\rm \scriptsize II}$] line at $158\,μ$m as a molecular gas tracer by analyzing the relationship between molecular gas mass ($M_{\rm mol}$) and [C${\rm \scriptsize II}$] line luminosity ($L_{\rm [CII]}$) in 11,125 $z\simeq 6$ star-forming, main sequence galaxies from the SIMBA simulations, with line emission modeled by SÍGAME. Though most ($\sim 50-100\,\%$) of the gas mass in our simulations is ionized, the bulk ($> 50\,\%$) of the [C${\rm \scriptsize II}$] emission comes from the molecular phase. We find a sub-linear (slope $0.78\pm 0.01$) $\log L_{\rm [C…
We present Herschel PACS observations of the [CII] 158 micron emission line in a sample of 24 intermediate mass (9<logM$_\ast$/M$_\odot$<10) and low metallicity (0.4< Z/Z$_\odot$<1.0) galaxies from the xCOLD GASS survey. Combining them with IRAM CO(1-0) measurements, we establish scaling relations between integrated and molecular region [CII]/CO(1-0) luminosity ratios as a function of integrated galaxy properties. A Bayesian analysis reveals that only two parameters, metallicity and offset from the star formation main sequence, $Δ$MS, are needed to quantify variations in the luminosity ratio; …
We present the detection of $^{12}$CO(2-1) in the $z = 4.44$ submillimetre galaxy ALESS65.1 using the Australia Telescope Compact Array. A previous ALMA study of submillimetre galaxies in the Extended Chandra Deep Field South determined the redshift of this optically and near-infrared undetected source through the measurement of [CII] 157.74 $μ$m emission. Using the luminosity of the $^{12}$CO(2-1) emission we estimate the gas mass to be $M_{\rm gas} \sim 1.7 \times 10^{10}$ ${\rm M}_\odot$. The gas depletion timescale of ALESS65.1 is $\sim$ 25 Myr, similar to other high redshift submillimetre…
[CII] as a global cold gas tracer in novel hydrodynamical simulations
Pontificia Universidad Católica de Chile（智利天主教 Pontificia 大学）；Instituto de Astrofísica, Pontificia Universidad Católica de Chile（智利天主教 Pontificia 大学天体物理研究所）；Centro de Astro-Ingeniería, Pontificia Universidad Católica de Chile（智利天主教 Pontificia 大学天文工程学中心）
本研究通过含 krome 化学包的 p-gadget-3 模拟，结合半解析模型分析孤立及并合星系，明确 [CII] 是全局冷气体可靠示踪剂，其发射本质依赖星系演化历史，约 50% 来自分子气体。
The [CII] fine-structure transition at 158 micron is frequently the brightest far-infrared line in galaxies. Due to its low ionization potential, C+ can trace the ionized, atomic, and molecular phases of the ISM. We present velocity resolved [CII] and [NII] pointed observations from SOFIA/GREAT on ~500 pc scales in the nearby galaxies M101 and NGC 6946 and investigate the multi-phase origin of [CII] emission over a range of environments. We show that ionized gas makes a negligible contribution to the [CII] emission in these positions using [NII] observations. We spectrally decompose the [CII] …
We present a new prediction of the luminosity functions of the [CII] line at 158 $μ$m, of the CO lines from J=0 to J=24, and of the molecular gas mass density up to z=10, using the Spectro-Photometric Realisations of Infrared-selected Targets at all-z (SPRITZ) simulation (Bisigello et al. 2021). We update the state-of-the-art phenomenological simulation SPRITZ to include both the CO ($J\leq24$) and [CII] line luminosities. This has been performed using different empirical and theoretical relations to convert the total infrared luminosity (or star formation rate) to [CII] or CO luminosity. The …
With the aim of improving predictions on far infrared (FIR) line emission from Giant Molecular Clouds (GMC), we study the effects of photoevaporation (PE) produced by external far-ultraviolet (FUV) and ionizing (extreme-ultraviolet, EUV) radiation on GMC structure. We consider three different GMCs with mass in the range $M_{\rm GMC} = 10^{3-6}\,\rm{M_{\odot}}$. Our model includes: (i) an observationally-based inhomogeneous GMC density field, and (ii) its time evolution during the PE process. In the fiducial case ($M_{\rm GMC}\approx10^5 M_{\odot}$), the photoevaporation time ($t_{pe}$) increas…
The [CII] 158 um fine structure line is one of the dominant cooling lines in the interstellar medium (ISM) and is an important tracer of star formation. Recent velocity-resolved studies with Herschel/HIFI and SOFIA/GREAT showed that the [CII] line can constrain the properties of the ISM phases in star-forming regions. The [CII] line as a tracer of star formation is particularly important in low-metallicity environments where CO emission is weak because of the presence of large amounts of CO-dark gas. The nearby irregular dwarf galaxy NGC 4214 offers an excellent opportunity to study an activel…
We analyse synthetic $^{12}$CO, $^{13}$CO, and [CII] emission maps of simulated molecular clouds of the SILCC-Zoom project, which include an on-the-fly evolution of H$_2$, CO, and C$^+$. We use simulations of hydrodynamical and magnetohydrodynamical clouds, both with and without stellar feedback. We introduce a novel post-processing of the C$^+$ abundance using CLOUDY, to account for further ionization states of carbon due to stellar radiation. We report the first self-consistent synthetic emission maps of [CII] in feedback bubbles, largely devoid of emission inside them, as recently found in …
ABRIDGED: Context: HI and CO large scale surveys of the Milky Way trace the diffuse atomic clouds and the dense shielded regions of molecular hydrogen clouds. However, until recently, we have not had spectrally resolved C+ surveys to characterize the photon dominated interstellar medium, including, the H2 gas without C, the CO-dark H2, in a large sample of clouds. Aims: To use a sparse Galactic plane survey of the 1.9 THz [C II] spectral line from the Herschel Open Time Key Programme, Galactic Observations of Terahertz C+ (GOT C+), to characterize the H2 gas without CO in a statistically signi…
CII fine-structure line observations of the Sagittarius C Region in the Galaxy's Central Molecular Zone
Max-Planck-Institut für Radioastronomie（马克斯·普朗克射电天文研究所）；Departamento de Astronomía, Universidad de La Serena（拉塞雷纳大学天文学系）；Department of Physics and Astronomy, University of California, Los Angeles（加州大学洛杉矶分校物理与天文学系）；Department of Astronomy, University of Maryland, College Park（马里兰大学天文学系）；Department of Physics, Astronomy, and Geosciences, Towson University（陶森大学物理、天文学和地球科学系）；I. Physikalisches Institut der Universität zu Köln（科隆大学第一物理研究所）；Institut de Radioastronomie Millimètrique（毫米波射电天文研究所）
We study the relationship between the [CII] emission and the star formation rate (SFR) in the Galactic plane and separate the relationship of different ISM phases to the SFR. We compare these relationships to those in external galaxies and local clouds, allowing examinations of these relationships over a wide range of physical scales. We compare the distribution of the [CII] emission, with its different contributing ISM phases, as a function of Galactocentric distance with the SFR derived from radio continuum observations. We also compare the SFR with the surface density distribution of atomic…
We investigate the large-scale structure of the interstellar medium (ISM) around the massive star cluster RCW38 in the [CII] 158 um line and polycyclic aromatic hydrocarbon (PAH) emission. We carried out [CII] line mapping of an area of ~30'x15' for RCW~38 by a Fabry-Perot spectrometer on a 100 cm balloon-borne telescope with an angular resolution of ~1'.5. We compared the [CII] intensity map with the PAH and dust emission maps obtained by the AKARI satellite. The [CII] emission shows a highly nonuniform distribution around the cluster, exhibiting the structure widely extended to the north and…
The [CII] $158\,μ\mathrm{m}$ fine-structure line is one of the dominant coolants of the neutral interstellar medium. It is hence one of the brightest far-infrared emission lines and can be observed not only in star-forming regions throughout the Galaxy, but also in the diffuse interstellar medium and in distant galaxies. [CII] line emission has been suggested to be a powerful tracer of star-formation. We aim to understand the origin of [CII] emission and its relation to other tracers of interstellar gas and dust. This includes a study of the heating efficiency of interstellar gas as traced by …
Molecular cloud dispersal traced by the ionized carbon 158 micron line
I. Physikalisches Institut, Universität zu Köln（科隆大学第一物理研究所）；Green Bank Observatory（格林班克天文台）；University of Maryland, Department of Astronomy（马里兰大学天文学系）；Leiden Observatory（莱顿天文台）；SOFIA Science Center, USRA, NASA Ames Research Center（NASA阿姆斯研究中心USRA SOFIA科学中心）；Astronomisches Rechen-Institut, ZfA Universität Heidelberg（海德堡大学ZfA天体计算研究所）；Center for Gravitational Waves and Cosmology, West Virginia University（西弗吉尼亚大学引力波与宇宙学中心）
We present new SOFIA [CII] and ALMA CO(J=1-0) observations of the nearby asymmetric barred spiral galaxy NGC 7479. The data, which cover the whole bar of the galaxy and the counter-arms visible in the radio continuum, are analyzed in conjunction with a wealth of existing visible, infrared, radio, and X-ray data. As in most normal galaxies, the [CII] emission is generally consistent with emission from cooling gas excited by photoelectric heating in photo-dissociation regions. However, anomalously high [CII]/CO ratios are seen at the two ends of the counter-arms. Both ends show shell-like struct…
Molecular globules and pillars are spectacular features, found only in the interface region between a molecular cloud and an HII-region. Impacting Far-ultraviolet (FUV) radiation creates photon dominated regions (PDRs) on their surfaces that can be traced by typical cooling lines. With the GREAT receiver onboard SOFIA we mapped and spectrally resolved the [CII] 158 micron atomic fine-structure line and the highly excited 12CO J=11-10 molecular line from three objects in Cygnus X (a pillar, a globule, and a strong IRAS source). We focus here on the globule and compare our data with existing Spi…
Molecular hydrogen clouds are a key component of the interstellar medium because they are the birthplaces for stars. They are embedded in atomic gas that pervades the interstellar space. However, the details of how molecular clouds assemble from and interact with the atomic gas are still largely unknown. As a result of new observations of the 158~$μ$m line of ionized carbon CII in the Cygnus region within the FEEDBACK program on SOFIA (Stratospheric Observatory for Infrared Astronomy), we present compelling evidence that CII unveils dynamic interactions between cloud ensembles. This process is…
Tracing the Hidden Molecular Gas in the Small Magellanic Cloud with SOFIA and APEX
Universidad de Concepción（康塞普西翁大学）；Millennium Nucleus for Galaxies (MINGAL)（星系千年核（MINGAL））；Max-Planck-Institut für extraterrestrische Physik（马克斯·普朗克地外物理研究所）；Universidad de Chile（智利大学）；University of Maryland（马里兰大学）；Joint Space-Science Institute（联合空间科学研究所）；Max-Planck-Institut für Radioastronomie（马克斯·普朗克射电天文学研究所）；Universidad de La Serena（拉塞雷纳大学）；Caltech Owens Valley Radio Observatory（加州理工学院欧文斯谷无线电天文台）；Leibniz-Institut für Astrophysik Potsdam (AIP)（波茨坦阿斯特诺物理莱布尼茨研究所（AIP））；Space Telescope Science Institute（太空望远镜科学研究所）；Universität zu Köln（科隆大学）
Extreme emission-line galaxies (EELGs) at redshift z=1-2 provide a unique view of metal-poor, starburst sources that are the likely drivers of the cosmic reionization at z$\geq6$. However, the molecular gas reservoirs of EELGs - the fuel for their intense star-formation - remain beyond the reach of current facilities. We present ALMA [CII] and PdBI CO(2-1) observations of a z=1.8, strongly lensed EELG SL2S 0217, a bright Lyman-$α$ emitter with a metallicity 0.05 $Z_\odot$. We obtain a tentative (3-4$σ$) detection of the [CII] line and set an upper limit on the [CII]/SFR ratio of $\leq1\times10…
We have mapped the NGC 2023 reflection nebula in [CII] and CO(11--10) with the heterodyne receiver GREAT on SOFIA and obtained slightly smaller maps in 13CO(3--2), CO(3--2), CO(4--3), CO(6--5), and CO(7--6) with APEX in Chile. We use these data to probe the morphology, kinematics, and physical conditions of the C II region, which is ionized by FUV radiation from the B2 star HD37903. The [CII] emission traces an ellipsoidal shell-like region at a position angle of ~ -50 deg, and is surrounded by a hot molecular shell. In the southeast, where the C II region expands into a dense, clumpy molecula…
