Infrared Emission from Interstellar Dust. II. The Diffuse Interstellar Medium

By Aigen Li, B. Draine. 2000

1,064 citations recorded by the source corpus.

We present a quantitative model for the infrared emission from dust in the diffuse interstellar medium. The model consists of a mixture of amorphous silicate grains and carbonaceous grains, each with a wide size distribution ranging from molecules containing tens of atoms to large grains ≳1 μm in diameter. We assume that the carbonaceous grains have properties like polycyclic aromatic hydrocarbons (PAHs) at very small sizes and graphitic properties for radii a ≳ 50 Å. On the basis of recent laboratory studies and guided by astronomical observations, we propose "astronomical" absorption cross sections for use in modeling neutral and ionized PAHs from the far-ultraviolet to the far-infrared. We also propose modifications to the far-infrared emissivity of "astronomical silicate." We calculate energy distribution functions for small grains undergoing "temperature spikes" caused by stochastic absorption of starlight photons using realistic heat capacities and optical properties. Using a grain-size distribution consistent with the observed interstellar extinction, we are able to reproduce the near-IR to submillimeter emission spectrum of the diffuse interstellar medium, including the PAH emission features at 3.3, 6.2, 7.7, 8.6, and 11.3 μm. The model is compared with the observed emission at high Galactic latitudes as well as in the Galactic plane, as measured by the COBE/DIRBE, COBE/FIRAS, IRTS/MIRS, and IRTS/NIRS instruments. The model has 60 × 10-6 of C (relative to H) locked up in PAHs, with 45 × 10-6 of C in a component peaking at ~6 Å (NC ≈ 100 carbon atoms) to account for the PAH emission features and with 15 × 10-6 of C in a component peaking at ~50 Å to account for the 60 μm flux. The total infrared emission is in excellent agreement with COBE/DIRBE observations at high Galactic latitudes, just as the albedo for our grain model is in accord with observations of the diffuse Galactic light. The aromatic absorption features at 3.3 and 6.2 μm predicted by our dust model are consistent with observations. We calculate infrared emission spectra for our dust model heated by a range of starlight intensities, from 0.3 to 104 times the local interstellar radiation field, and we tabulate the intensities integrated over the SIRTF/IRAC and MIPS bands. We also provide dust opacities tabulated from the extreme-ultraviolet to submillimeter wavelengths.

Subfields: Astronomy and Astrophysics, Atmospheric Science

View Paper: https://www.semanticscholar.org/paper/1ea17cf43d267b24b9d0ec45dda186394e87f345

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In Astronomy and Astrophysics

1. P. Hopkins
2. L. Hernquist
3. R. Somerville
4. D. Narayanan
5. R. Dav'e
6. Mark R. Krumholz
7. Thomas J. Cox
8. C. Conroy

In Atmospheric Science

1. E. Dishoeck
2. Simon Bruderer
3. A. Tielens
4. E. Peeters
5. E. Quataert
6. L. Allamandola
7. B. Draine
8. N. Evans II

Citations in the corpus

• The Dust Opacity of Star‐forming Galaxies (2001, background): “…photon heating of very small dust grains, the smallest among which are transiently heated up to ≈1,000 K (e.g., Sellgren 1984; Draine & Anderson 1985; Li & Draine 2001); dust heated by massive stars to temperatures >70 K also contributes to the flux in the wavelength region below ∼50 µm, albeit…”
• Cool outflows in galaxies and their implications (2020, background): “The dust grain can also scatter the Lyα photon with a probability given by its albedo, As = 0.32 at the Lyα wavelength for dust made mainly of graphite and silicates (Li and Draine 2001).”
• Herschel-ATLAS: rapid evolution of dust in galaxies over the last 5 billion years (2010, neutral): “For galaxies in the Millennium Survey (Driver et al. 2007) the Li & Draine (2001) values of κ (which are lower than those used here by 70 per cent) gave the best consistency with the observed attenuation–inclination relation; however it will be interesting to see the results of similar modelling…”
• STAR FORMATION IN THE CENTRAL 400 PC OF THE MILKY WAY: EVIDENCE FOR A POPULATION OF MASSIVE YOUNG STELLAR OBJECTS (2009, background): “Thermal emission from small dust grains becomes strong enough to compete with the PAH emission in the 8µm band only when the local radiation field is about 104 times that of the solar neighborhood (Li & Draine 2001).”
• Warm Molecular Hydrogen in the Spitzer SINGS Galaxy Sample (2007, background): “Aromatic band carriers can also be excited by lower energy photons in the ultraviolet and optical, but with smaller absorption cross sections (see Li & Draine 2001), so that FUV photons will dominate the excitation whenever massive stars are present.”
• OBSERVATIONS OF Arp 220 USING HERSCHEL-SPIRE: AN UNPRECEDENTED VIEW OF THE MOLECULAR GAS IN AN EXTREME STAR FORMATION ENVIRONMENT (2011, methodology): “Also, even for dust heated by a uniform radiation field, transiently-heated smaller dust grains will typically produce emission that peaks at shorter wavelengths, while the larger dust grains will appear to be in thermal equilibrium at 15-30 K (e.g., Li & Draine 2001; Draine & Li 2007).”
• THE SPITZER LOCAL VOLUME LEGACY: SURVEY DESCRIPTION AND INFRARED PHOTOMETRY (2009, methodology): “…extinction in the LVL sample using this method is 0.54 mag with ninety percent of the sources having far-ultraviolet extinctions less than 1.7 mag, or equivalently with the aid of the Li & Draine (2001) extinction curve, the median optical extinction is AV ∼ 0.2 mag and ninety percent have AV .”
• HERSCHEL FAR-INFRARED AND SUBMILLIMETER PHOTOMETRY FOR THE KINGFISH SAMPLE OF NEARBY GALAXIES (2011, methodology): “The Draine & Li (2007) dust models use the far-infrared and sub-millimeter opacities for graphite and amorphous silicate from Li & Draine (2001).”
• Modeling the Pan-Spectral Energy Distribution of Starburst Galaxies. IV. The Controlling Parameters of the Starburst SED (2007, methodology): “The optical data for each of these comes from the series of work by Draine et al.8 (Laor & Draine 1993; Li & Draine 2001).”
• What Is the Total Deuterium Abundance in the Local Galactic Disk? (2006, background): “…surface area available for deuterium depletion is provided by the population of free-flying PAHs, but this population is thought to contain only CPAH/Htotal ≈ 60 ppm (Li & Draine 2001), or ∼1/3 of the total aromatic material, with the remaining carbonaceous material in grains with radii a & 150 Å.”
• The dust covering factor in active galactic nuclei (2016, methodology): “…is modeled as a mixture of silicate and graphite grains with classical MRN size distribution (Mathis, Rumpl & Nordsieck 1977), with the normalization factors for size distribution from Weingartner & Draine (2001), and with optical properties taken from Laor & Draine (1993) and Li & Draine (2001).”
• Investigations of dust heating in M81, M83 and NGC 2403 with the Herschel Space Observatory (2011, background): “We useβ = 2 (given by Li & Draine 2001) for this calculation, as it has previously been shown to accurately describe the observed emissivity of dust.”
• COMBINED CO AND DUST SCALING RELATIONS OF DEPLETION TIME AND MOLECULAR GAS FRACTIONS WITH COSMIC TIME, SPECIFIC STAR-FORMATION RATE, AND STELLAR MASS (2014, methodology): “We fitted the models following the procedure prescribed by these authors, and widely used in the literature, adopting the Li & Draine (2001) values of dust opacity as a function of wavelength.”
• A simple model to interpret the ultraviolet, optical and infrared emission from galaxies (2008, positive): “We set the amplitude f0 so that the luminosity of the 3.3 µm emission feature is 10 per cent of that of the 11.3 µm feature (the relative ratio found by Li & Draine 2001 for neutral PAHs).”
• A physical model for z∼ 2 dust-obscured galaxies (2009, methodology): “Their absorption is calculated utilizing the Li & Draine (2001) cross-sections.”
• Variations in the Peak Position of the 6.2 μm Interstellar Emission Feature: A Tracer of N in the Interstellar Polycyclic Aromatic Hydrocarbon Population (2005, background): “…pattern of band positions, intensities, and profiles observed in the interstellar IR emission spectra as well as the variations in those characteristics (e.g., Langhoff 1996; Allamandola et al. 1999; Verstraete et al. 2001; Bakes et al. 2001, Draine & Li 2001; Li & Draine 2001; Pech et al. 2002).”
• DUST-CORRECTED STAR FORMATION RATES OF GALAXIES. II. COMBINATIONS OF ULTRAVIOLET AND INFRARED TRACERS (2011, methodology): “Since Dale et al. (2007) used Li & Draine (2001) reddening curve to correct for the Galactic extinction, we redid the Galactic extinction using the same recipes as those used for the MK06 sample for consistency4.”
• The Infrared Spectra of Very Large, Compact, Highly Symmetric, Polycyclic Aromatic Hydrocarbons (PAHs) (2008, background): “…2000; Vermeij et al. 2002; Peeters et al. 2004; Bregman & Temi 2005; Brandl et al. 2006; Sellgren et al. 2007; Smith et al. 2007; Galliano et al. 2008), and they account for 10%Y30% of cosmic carbon (Snow &Witt 1995; Puget & Léger 1989; Allamandola et al. 1989; Li & Draine 2001; Draine & Li 2007).”
• Dust spectral energy distributions of nearby galaxies: an insight from the Herschel Reference Survey (2014, background): “…1984; Kim et al. 1994), and are extended by adding the contribution of the polycyclic aromatic hydrocarbons (PAH), producing the broad spectral features seen in the mid-IR (MIR), such as in Siebenmorgen & Kruegel (1992), Li & Draine (2001), Weingartner & Draine (2001) and Draine & Li (2007) models.”