- ID:
- ivo://CDS.VizieR/J/ApJ/846/32
- Title:
- Herschel FIR spectra of GOALS galaxies
- Short Name:
- J/ApJ/846/32
- Date:
- 13 Dec 2021 06:52:25
- Publisher:
- CDS
- Description:
- We present an analysis of [OI]_63_, [OIII]_88_, [NII]_122_, and [CII]_158_ far-infrared (FIR) fine-structure line observations obtained with Herschel/PACS, for ~240 local luminous infrared galaxies (LIRGs) in the Great Observatories All-sky LIRG Survey. We find pronounced declines ("deficits") of line-to-FIR continuum emission for [NII]_122_, [OI]_63_, and [CII]_158_ as a function of FIR color and infrared luminosity surface density, {Sigma}_IR_. The median electron density of the ionized gas in LIRGs, based on the [NII]_122_/[NII]_205_ ratio, is n_e_=41cm^-3^. We find that the dispersion in the [CII]_158_ deficit of LIRGs is attributed to a varying fractional contribution of photodissociation regions (PDRs) to the observed [CII]_158_ emission, f([CII]_158_^PDR^)=[CII]_158_^PDR^/[CII]_158_, which increases from ~60% to ~95% in the warmest LIRGs. The [OI]_63_/[CII]_158_^PDR^ ratio is tightly correlated with the PDR gas kinetic temperature in sources where [OI]_63_ is not optically thick or self-absorbed. For each galaxy, we derive the average PDR hydrogen density, n_H_, and intensity of the interstellar radiation field, G, in units of G_0_ and find G/n_H_ ratios of ~0.1-50G_0_.cm^3^, with ULIRGs populating the upper end of the distribution. There is a relation between G/n_H_ and {Sigma}_IR_, showing a critical break at {Sigma}_IR_^*^~5x10^10^L_{sun}_/kpc^2^. Below {Sigma}_IR_^*^, G/n_H_ remains constant, ~0.32G_0_.cm^3^, and variations in {Sigma}_IR_ are driven by the number density of star-forming regions within a galaxy, with no change in their PDR properties. Above {Sigma}_IR_^*^, G/n_H_ increases rapidly with {Sigma}_IR_, signaling a departure from the typical PDR conditions found in normal star-forming galaxies toward more intense/harder radiation fields and compact geometries typical of starbursting sources.
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- ID:
- ivo://CDS.VizieR/J/ApJ/814/133
- Title:
- Herschel Galactic plane survey of [NII]
- Short Name:
- J/ApJ/814/133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first large-scale high angular resolution survey of ionized nitrogen in the Galactic Plane through emission of its two fine structure transitions ([N II]) at 122 and 205 {mu}m. The observations were largely obtained with the PACS instrument onboard the Herschel Space Observatory. The lines of sight were in the Galactic plane, following those of the Herschel OTKP project GOT C+. Both lines are reliably detected at the 10^-8^-10^-7^ W/m^2^/sr level over the range -60{deg}<=l<=60{deg}. The rms of the intensity among the 25 PACS spaxels of a given pointing is typically less than one third of the mean intensity, showing that the emission is extended. [N II] is produced in gas in which hydrogen is ionized, and collisional excitation is by electrons. The ratio of the two fine structure transitions provides a direct measurement of the electron density, yielding n(e) largely in the range 10-50 cm^-3^ with an average value of 29 cm^-3^ and N^+^ column densities 10^16^-10^17^ cm^-2^. [N II] emission is highly correlated with that of [C II], and we calculate that between 1/3 and 1/2 of the [C II] emission is associated with the ionized gas. The relatively high electron densities indicate that the source of the [N II] emission is not the warm ionized medium (WIM), which has electron densities more than 100 times smaller. Possible origins of the observed [N II] include the ionized surfaces of dense atomic and molecular clouds, the extended low-density envelopes of H II regions, and low-filling factor high-density fluctuations of the WIM.
- ID:
- ivo://CDS.VizieR/J/A+A/542/A76
- Title:
- Herschel-HIFI water spectra of W43-MM1
- Short Name:
- J/A+A/542/A76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Herschel/HIFI observations of 14 water lines in W43-MM1, a massive protostellar object in the luminous star-cluster-forming region W43. We place our study in the more general context of high-mass star formation. The dynamics of these regions may be represented by either the monolithic collapse of a turbulent core, or competitive accretion. Water turns out to be a particularly good tracer of the structure and kinematics of the inner regions, allowing an improved description of the physical structure of the massive protostar W43-MM1 and an estimation of the amount of water around it. We analyze the gas dynamics from the line profiles using Herschel-HIFI observations acquired as part of the Water In Star-forming regions with Herschel project of 14 far-IR water lines (H_2_^16^O, H_2_^17^O, H_2_^18^O), CS(11-10), and C^18^O(9-8) lines, using our modeling of the continuum spectral energy distribution. The spectral modeling tools allow us to estimate outflow, infall, and turbulent velocities and molecular abundances. We compare our results to previous studies of low-, intermediate-, and other high-mass objects. As for lower-mass protostellar objects, the molecular line profiles are a mix of emission and absorption, and can be decomposed into 'medium' (full width at half maximum FWHM~=5-10km/s), and 'broad' velocity components (FWHM~=20-35km/s). The broad component is the outflow associated with protostars of all masses. Our modeling shows that the remainder of the water profiles can be well-fitted by an infalling and passively heated envelope, with highly supersonic turbulence varying from 2.2km/s in the inner region to 3.5km/s in the outer envelope. In addition, W43-MM1 has a high accretion rate of between 4.0x10^-4^ and 4.0x10^-2^M_{sun}_/yr, as derived from the fast (0.4-2.9km/s) infall observed. We estimate a lower mass limit for gaseous water of 0.11M_{sun}_ and total water luminosity of 1.5L_{sun}_ (in the 14 lines presented here). The central hot core is detected with a water abundance of 1.4x10^-4^, while the water abundance for the outer envelope is 8x10^-8^. The latter value is higher than in other sources, and most likely related to the high turbulence and the micro-shocks created by its dissipation. Examining the water lines of various energies, we find that the turbulent velocity increases with the distance from the center. While not in clear disagreement with the competitive accretion scenario, this behavior is predicted by the turbulent core model. Moreover, the estimated accretion rate is high enough to overcome the expected radiation pressure.
- ID:
- ivo://CDS.VizieR/J/AJ/151/75
- Title:
- Herschel-PACS and -SPIRE spectroscopy of 70 objects
- Short Name:
- J/AJ/151/75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the COPS-DIGIT-FOOSH (CDF) Herschel spectroscopy data product archive, and related ancillary data products, along with data fidelity assessments, and a user-created archive in collaboration with the Herschel-PACS and SPIRE ICC groups. Our products include datacubes, contour maps, automated line fitting results, and best 1D spectra products for all protostellar and disk sources observed with PACS in RangeScan mode for two observing programs: the DIGIT Open Time Key Program (KPOT\_nevans\_1 and SDP\_nevans\_1; PI: N. Evans), and the FOOSH Open Time Program (OT1\_jgreen02\_2; PI: J. Green). In addition, we provide our best SPIRE-FTS spectroscopic products for the COPS Open Time Program (OT2\_jgreen02\_6; PI: J. Green) and FOOSH sources. We include details of data processing, descriptions of output products, and tests of their reliability for user applications. We identify the parts of the data set to be used with caution. The resulting absolute flux calibration has improved in almost all cases. Compared to previous reductions, the resulting rotational temperatures and numbers of CO molecules have changed substantially in some sources. On average, however, the rotational temperatures have not changed substantially (<2%), but the number of warm (T_rot_~300K) CO molecules has increased by about 18%.
- ID:
- ivo://CDS.VizieR/J/A+A/565/A109
- Title:
- Herschel/PACS spectra of 48 evolved stars
- Short Name:
- J/A+A/565/A109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 48 Herschel/PACS spectra of evolved stars in the wavelength range of 67-72um. This wavelength range covers the 69mu band of crystalline olivine (Mg_2-2x_Fe_(2x)_SiO_4_). The width and wavelength position of this band are sensitive to the temperature and composition of the crystalline olivine. Our sample covers a wide range of objects: from high mass-loss rate AGB stars (OH/IR stars, dM/dt>=10^-5^M_{sun}_/yr), through post-AGB stars with and without circumbinary disks, to planetary nebulae and even a few massive evolved stars. The goal of this study is to exploit the spectral properties of the 69um band to determine the composition and temperature of the crystalline olivine. Since the objects cover a range of evolutionary phases, we study the physical and chemical properties in this range of physical environments. We fit the 69um band and use its width and position to probe the composition and temperature of the crystalline olivine. For 27 sources in the sample, we detected the 69um band of crystalline olivine (Mg_2-2x_Fe_(2x)_SiO_4_). The 69um band shows that all the sources produce pure forsterite grains containing no iron in their lattice structure. The temperature of the crystalline olivine as indicated by the 69um band, shows that on average the temperature of the crystalline olivine is highest in the group of OH/IR stars and the post-AGB stars with confirmed Keplerian disks. The temperature is lower for the other post-AGB stars and lowest for the planetary nebulae. A couple of the detected 69um bands are broader than those of pure magnesium-rich crystalline olivine, which we show can be due to a temperature gradient in the circumstellar environment of these stars. The disk sources in our sample with crystalline olivine are very diverse. They show either no 69um band, a moderately strong band, or a very strong band, together with a temperature for the crystalline olivine in their disk that is either very warm (~600K), moderately warm (~200K), or cold (~120K), respectively.
- ID:
- ivo://CDS.VizieR/J/ApJ/841/116
- Title:
- Herschel spectra of 11 very low mass stars
- Short Name:
- J/ApJ/841/116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The properties of disks around brown dwarfs and very low mass stars (hereafter VLMOs) provide important boundary conditions on the process of planet formation and inform us about the numbers and masses of planets than can form in this regime. We use the Herschel Space Observatory PACS spectrometer to measure the continuum and [OI]63{mu}m line emission toward 11 VLMOs with known disks in the Taurus and Chamaeleon I star-forming regions. We fit radiative transfer models to the spectral energy distributions of these sources. Additionally, we carry out a grid of radiative transfer models run in a regime that connects the luminosity of our sources with brighter T Tauri stars. We find that VLMO disks with sizes 1.3-78au, smaller than typical T Tauri disks, fit well the spectral energy distributions assuming that disk geometry and dust properties are stellar mass independent. Reducing the disk size increases the disk temperature, and we show that VLMOs do not follow previously derived disk temperature-stellar luminosity relationships if the disk outer radius scales with stellar mass. Only 2 out of 11 sources are detected in [OI] despite a better sensitivity than was achieved for T Tauri stars, suggesting that VLMO disks are underluminous. Using thermochemical models, we show that smaller disks can lead to the unexpected [OI]63{mu}m nondetections in our sample. The disk outer radius is an important factor in determining the gas and dust observables.
- ID:
- ivo://CDS.VizieR/J/ApJ/887/105
- Title:
- Herschel/SPIRE FTS [CI] lines in KINGFISH gal.
- Short Name:
- J/ApJ/887/105
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present resolved [CI] line intensities of 18 nearby galaxies observed with the SPIRE FTS spectrometer on the Herschel Space Observatory. We use these data along with resolved CO line intensities from J_up_=1 to 7 to interpret what phase of the interstellar medium the [CI] lines trace within typical local galaxies. A tight, linear relation is found between the intensities of the CO(4-3) and [CI](2-1) lines; we hypothesize this is due to the similar upper level temperature of these two lines. We modeled the [CI] and CO line emission using large-velocity gradient models combined with an empirical template. According to this modeling, the [CI](1-0) line is clearly dominated by the low-excitation component. We determine [CI] to molecular mass conversion factors for both the [CI](1-0) and [CI](2-1) lines, with mean values of {alpha}_[CI](1-0)_=7.3M_{sun}_/K/km.s/pc^2^ and {alpha}_[CI](2-1)_=34M_{sun}_/K/km.s/pc^2^ with logarithmic root-mean-square spreads of 0.20 and 0.32dex, respectively. The similar spread of {alpha}_[CI](1-0)_ to {alpha}_CO_ (derived using the CO(2-1) line) suggests that [CI](1-0) may be just as good a tracer of cold molecular gas as CO(2-1) in galaxies of this type. On the other hand, the wider spread of {alpha}_[CI](2-1)_ and the tight relation found between [CI](2-1) and CO(4-3) suggest that much of the [CI](2-1) emission may originate in warmer molecular gas.
- ID:
- ivo://CDS.VizieR/J/ApJS/230/1
- Title:
- Herschel SPIRE/FTS 194-671um survey of GOALS LIRGs
- Short Name:
- J/ApJS/230/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe a Herschel Space Observatory 194-671{mu}m spectroscopic survey of a sample of 121 local luminous infrared galaxies and report the fluxes of the CO J to J-1 rotational transitions for 4<=J<=13, the [NII] 205{mu}m line, the [CI] lines at 609 and 370{mu}m, as well as additional and usually fainter lines. The CO spectral line energy distributions (SLEDs) presented here are consistent with our earlier work, which was based on a smaller sample, that calls for two distinct molecular gas components in general: (i) a cold component, which emits CO lines primarily at J<~4 and likely represents the same gas phase traced by CO (1-0), and (ii) a warm component, which dominates over the mid-J regime (4<J<~10) and is intimately related to current star formation. We present evidence that the CO line emission associated with an active galactic nucleus is significant only at J>10. The flux ratios of the two [CI] lines imply modest excitation temperatures of 15-30K; the [CI] 370{mu}m line scales more linearly in flux with CO (4-3) than with CO (7-6). These findings suggest that the [CI] emission is predominantly associated with the gas component defined in (i) above. Our analysis of the stacked spectra in different far-infrared (FIR) color bins reveals an evolution of the SLED of the rotational transitions of H_2_O vapor as a function of the FIR color in a direction consistent with infrared photon pumping.
- ID:
- ivo://CDS.VizieR/J/A+A/568/A90
- Title:
- Herschel/SPIRE spectra in Arp 299
- Short Name:
- J/A+A/568/A90
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (Ultra) luminous infrared galaxies ((U)LIRGs) are nearby laboratories that allow us to study similar processes to those occurring in high redshift submillimeter galaxies. Understanding the heating and cooling mechanisms in these galaxies can give us insight into the driving mechanisms in their more distant counterparts. Molecular emission lines play a crucial role in cooling excited gas, and recently, with Herschel Space Observatory we have been able to observe the rich molecular spectrum. Carbon monoxide (CO) is the most abundant and one of the brightest molecules in the Herschel wavelength range. CO transitions from J=4-3 to 13-12 are observed with Herschel, and together, these lines trace the excitation of CO. We study Arp 299, a colliding galaxy group, with one component (A) harboring an active galactic nucleus and two more (B and C) undergoing intense star formation. For Arp 299 A, we present PACS spectrometer observations of high-J CO lines up to J=20-19 and JCMT observations of ^13^CO and HCN to discern between UV heating and alternative heating mechanisms.
- ID:
- ivo://CDS.VizieR/J/ApJ/736/31
- Title:
- HETDEX pilot survey. II. 1.9<z<3.8 LAEs
- Short Name:
- J/ApJ/736/31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the escape of Ly{alpha} photons from Ly{alpha} emitting galaxies (LAEs) and the overall galaxy population using a sample of 99 LAEs at 1.9<z<3.8 detected through integral-field spectroscopy of blank fields by The Hobby Eberly Telescope Dark Energy Experiment Pilot Survey. For 89 LAEs with broadband counterparts we measure ultraviolet (UV) luminosities and UV slopes, and estimate E(B-V) under the assumption of a constant intrinsic UV slope for LAEs. These quantities are used to estimate dust-corrected star formation rates (SFRs). Comparison between the observed Ly{alpha} luminosity and that predicted by the dust-corrected SFR yields the Ly{alpha} escape fraction. We also measure the Ly{alpha} luminosity function and luminosity density ({rho}_Ly{alpha}_) at 2<z<4. Using this and other measurements from the literature at 0.3<z<7.7 we trace the redshift evolution of {rho}_Ly{alpha}_. We compare it to the expectations from the star formation history of the universe and characterize the evolution of the Ly{alpha} escape fraction of galaxies.
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