Journal ArticleDOI
Far-Infrared and Submillimeter Emission from Galactic and Extragalactic Photodissociation Regions
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In this article, the effects of metallicity and cloud extinction on the predicted line intensities were examined for a wide range of physical conditions, from those appropriate to giant molecular clouds illuminated by the interstellar radiation field to the conditions experienced by circumstellar disks very close to hot massive stars.Abstract:
Photodissociation region (PDR) models are computed over a wide range of physical conditions, from those appropriate to giant molecular clouds illuminated by the interstellar radiation field to the conditions experienced by circumstellar disks very close to hot massive stars. These models use the most up-to-date values of atomic and molecular data, the most current chemical rate coefficients, and the newest grain photoelectric heating rates, which include treatments of small grains and large molecules. In addition, we examine the effects of metallicity and cloud extinction on the predicted line intensities. Results are presented for PDR models with densities over the range n = 101-107 cm-3 and for incident far-ultraviolet radiation fields over the range G0 = 10-0.5-106.5 (where G0 is the far-ultravioliet [FUV] flux in units of the local interstellar value), for metallicities Z = 1 and 0.1 times the local Galactic value, and for a range of PDR cloud sizes. We present line strength and/or line ratio plots for a variety of useful PDR diagnostics: [C II] 158 μm, [O I] 63 μm and 145 μm, [C I] 370 μm and 609 μm, CO J = 1-0, J = 2-1, J = 3-2, J = 6-5, and J = 15-14, as well as the strength of the far-infrared continuum. These plots will be useful for the interpretation of Galactic and extragalactic far-infrared and submillimeter spectra observable with the Infrared Space Observatory (ISO), the Stratospheric Observatory for Infrared Astronomy, the Submillimeter Wave Astronomy Satellite, the Far Infrared and Submillimeter Telescope, and other orbital and suborbital platforms. As examples, we apply our results to ISO and ground-based observations of M82, NGC 278, and the Large Magellanic Cloud. Our comparison of the conditions in M82 and NGC 278 show that both the gas density and FUV flux are enhanced in the starburst nucleus of M82 compared with those in the normal spiral NGC 278. We model the high [C II]/CO ratio observed in the 30 Doradus region of the LMC and find that it can be explained either by lowering the average extinction through molecular clouds or by enhancing the density contrast between the atomic layers of PDRs and the CO-emitting cloud cores. The ratio L[CO]/M[H2] implied by the low extinction model gives cloud masses too high for gravitational stability. We therefore rule out low-extinction clouds as an explanation for the high [C II]/CO ratio and instead appeal to density contrast in AV = 10 clouds.read more
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Journal ArticleDOI
Far-Infrared Detection of Neutral Atomic Oxygen Toward the Horsehead Nebula
TL;DR: In this paper, the first detection of the neutral atomic oxygen (3 P 1-3 P 2 fine structure line at ~63m) toward the Horsehead photodissociation region (PDR) was presented.
Journal ArticleDOI
Residual cooling and persistent star formation amid active galactic nucleus feedback in Abell 2597
Grant R. Tremblay,Grant R. Tremblay,Grant R. Tremblay,Christopher P. O'Dea,Christopher P. O'Dea,Stefi A. Baum,Stefi A. Baum,Tracy E. Clarke,Craig L. Sarazin,Joel N. Bregman,Francoise Combes,Megan Donahue,Alastair C. Edge,A. C. Fabian,Gary J. Ferland,Brian R. McNamara,Brian R. McNamara,Rupal Mittal,J. B. R. Oonk,Alice C. Quillen,Helen Russell,Jeremy S. Sanders,P. Salomé,G. M. Voit,R. J. Wilman,Michael W. Wise +25 more
TL;DR: In this article, Chandra X-ray and Herschel Far-Infrared (FIR) observations enable a multiwavelength study of active galactic nucleus (AGN) heating and ICM cooling in the brightest cluster galaxy (BCG) of Abell 2597 (z= 0.0821).
Journal ArticleDOI
Origin of the dense core mass function in contracting filaments
TL;DR: In this article, the mass functions of starless dense cores (CMFs) may arise from contraction and dispersal of core-forming filaments, where a filament contracts radially by self-gravity, increasing the mass of its cores.
Journal ArticleDOI
WARPFIELD-EMP: The self-consistent prediction of emission lines from evolving H II regions in dense molecular clouds
Eric W. Pellegrini,Daniel Rahner,Stefan Reissl,Simon C. O. Glover,Ralf S. Klessen,Laurie Rousseau-Nepton,Rodrigo Herrera-Camus +6 more
TL;DR: In this paper, the authors present a warpfield-based emission predictor for the time-dependent line and continuum emission arising from the H{sc ii} region and PDR surrounding an evolving star cluster.
Journal ArticleDOI
ISO observation of molecular hydrogen and fine-structure lines in the photodissociation region IC 63
TL;DR: In this paper, the main physical properties of the photodissociation region (PDR) IC 63 were investigated and the results of a survey for the lowest pure-rotational lines of H_2 with the Short Wavelength Spectrometer and for the major fine-structure cooling lines of O i at 63 and 145 μm and C ii at 157.7 μm with the Long Wavelength spectrometer on board the Infrared Space Observatory (ISO) in the high density PDR IC 63.
References
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TL;DR: In this article, a theoretical parameter study of the temperature and chemical structure of dense photodissociation regions and their resultant spectrum is presented, which is relevant not only to the dust and gas between molecular clouds and H II regions, but also apply to any neutral cloud illuminated by intense FUV fluxes.
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The neutral atomic phases of the interstellar medium
Mark Wolfire,David Hollenbach,Christopher F. McKee,Alexander G. G. M. Tielens,E. L. O. Bakes +4 more
TL;DR: In this paper, a photoelectric heating rate from small grains and polycyclic aromatic hydrocarbons (PAHs) was proposed to account for the size distribution of particles extending from 100 to 3 A radius.