arXiv subjects

A. Contursi

Publications and source records attributed to A. Contursi.

At least 55 records · Page 3Linked to original sources

arXiv2011

Massive molecular outflows and negative feedback in ULIRGs observed by Herschel-PACS

Mass outflows driven by stars and active galactic nuclei are a key element in many current models of galaxy evolution. They may produce the observed black hole-galaxy mass relation and regulate and quench both star formation in the host galaxy and black hole accretion. However, observational evidence of such feedback processes through outflows of the bulk of the star forming molecular gas is still scarce. Here we report the detection of massive molecular outflows, traced by the hydroxyl molecule (OH), in far-infrared spectra of ULIRGs obtained with Herschel-PACS as part of the SHINING key project. In some of these objects the (terminal) outflow velocities exceed 1000 km/s, and their outflow rates (up to ~1200 M_sol/yr) are several times larger than their star formation rates. We compare the outflow signatures in different types of ULIRGs and in starburst galaxies to address the issue of the energy source (AGN or starburst) of these outflows. We report preliminary evidence that ULIRGs with a higher AGN luminosity (and higher AGN contribution to L_IR) have higher terminal velocities and shorter gas depletion time scales. The outflows in the observed ULIRGs are able to expel the cold gas reservoirs from the centres of these objects within ~1E6-1E8 years.

astro-ph.CO↗

arXiv2011

Far-Infrared Line Deficits in Galaxies with Extreme Lfir/MH2 Ratios

We report initial results from the far-infrared fine structure line observations of a sample of 44 local starbursts, Seyfert galaxies and infrared luminous galaxies obtained with the PACS spectrometer on board Herschel. We show that the ratio between the far-infrared luminosity and the molecular gas mass, Lfir/MH2, is a much better proxy for the relative brightness of the far-infrared lines than Lfir alone. Galaxies with high Lfir/MH2 ratios tend to have weaker fine structure lines relative to their far-infrared continuum than galaxies with Lfir/MH2 < 80 Lsun/Msun. A deficit of the [C II] 158 micron line relative to Lfir was previously found with the ISO satellite, but now we show for the first time that this is a general aspect of all far-infrared fine structure lines, regardless of their origin in the ionized or neutral phase of the interstellar medium. The Lfir/MH2 value where these line deficits start to manifest is similar to the limit that separates between the two modes of star formation recently found in galaxies on the basis of studies of their gas-star formation relations. Our finding that the properties of the interstellar medium are also significantly different in these regimes provides independent support for the different star forming relations in normal disk galaxies and major merger systems. We use the spectral synthesis code Cloudy to model the emission of the lines. The expected increase of the ionization parameter with Lfir/MH2 can simultaneously explain the line deficits in the [C II], [N II] and [O I] lines.

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arXiv2010

The Photodetector Array Camera and Spectrometer (PACS) on the Herschel Space Observatory

The Photodetector Array Camera and Spectrometer (PACS) is one of the three science instruments on ESA's far infrared and submillimetre observatory. It employs two Ge:Ga photoconductor arrays (stressed and unstressed) with 16x25 pixels, each, and two filled silicon bolometer arrays with 16x32 and 32x64 pixels, respectively, to perform integral-field spectroscopy and imaging photometry in the 60-210μ m wavelength regime. In photometry mode, it simultaneously images two bands, 60-85μ m or 85-125μ\m and 125-210μ m, over a field of view of ~1.75'x3.5', with close to Nyquist beam sampling in each band. In spectroscopy mode, it images a field of 47"x47", resolved into 5x5 pixels, with an instantaneous spectral coverage of ~1500km/s and a spectral resolution of ~175km/s. We summarise the design of the instrument, describe observing modes, calibration, and data analysis methods, and present our current assessment of the in-orbit performance of the instrument based on the Performance Verification tests. PACS is fully operational, and the achieved performance is close to or better than the pre-launch predictions.

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arXiv2010

Herschel-PACS spectroscopy of IR-bright galaxies at high redshift

We present Herschel-PACS observations of rest-frame mid-infrared and far-infrared spectral line emissions from two lensed, ultra-luminous infrared galaxies at high redshift: MIPS J142824.0+352619 (MIPS J1428), a starburst-dominated system at z = 1.3, and IRAS F10214+4724 (F10214), a source at z = 2.3 hosting both star-formation and a luminous AGN. We have detected [OI]63 micron and [OIII]52 micron in MIPS J1428, and tentatively [OIII]52 micron in F10214. Together with the recent ZEUS-CSO [CII]158 micron detection in MIPS J1428 we can for the first time combine [OI], [CII] and far-IR (FIR) continuum measurements for photo-dissociation (PDR) modeling of an ultra-luminous (L_IR > 10^12 L_sun) star forming galaxy at the peak epoch of cosmic star formation. We find that MIPS J1428, contrary to average local ULIRGs, does not show a deficit in [OI] relative to FIR. The combination of far-UV flux G_0 and gas density n (derived from the PDR models), as well as the star formation efficiency (derived from CO and FIR) is similar to normal or starburst galaxies, despite the high infrared luminosity of this system. In contrast, F10214 has stringent upper limits on [OIV] and [SIII], and an [OIII]/FIR ratio at least an order of magnitude lower than local starbursts or AGN, similar to local ULIRGs.

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arXiv2010

The effects of star formation on the low-metallicity ISM: NGC4214 mapped with Herschel/PACS spectroscopy

We present Herschel/PACS spectroscopic maps of the dwarf galaxy NC4214 observed in 6 far infrared fine-structure lines: [C II] 158mu, [O III] 88mu, [O I] 63mu, [O I] 146mu, [N II] 122mu, and [N II] 205mu. The maps are sampled to the full telescope spatial resolution and reveal unprecedented detail on ~ 150 pc size scales. We detect [C II] emission over the whole mapped area, [O III] being the most luminous FIR line. The ratio of [O III]/[C II] peaks at about 2 toward the sites of massive star formation, higher than ratios seen in dusty starburst galaxies. The [C II]/CO ratios are 20 000 to 70 000 toward the 2 massive clusters, which are at least an order of magnitude larger than spiral or dusty starbursts, and cannot be reconciled with single-slab PDR models. Toward the 2 massive star-forming regions, we find that L[CII] is 0.5 to 0.8% of the LTIR . All of the lines together contribute up to 2% of LTIR . These extreme findings are a consequence of the lower metallicity and young, massive-star formation commonly found in dwarf galaxies. These conditions promote large-scale photodissociation into the molecular reservoir, which is evident in the FIR line ratios. This illustrates the necessity to move to multiphase models applicable to star-forming clusters or galaxies as a whole.

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arXiv2009

A Deep HST H-Band Imaging Survey of Massive Gas-Rich Mergers. II. The QUEST PG QSOs

We report the results from a deep HST NICMOS H-band imaging survey of 28 z < 0.3 QSOs from the Palomar-Green (PG) sample. This program is part of QUEST (Quasar / ULIRG Evolution STudy) and complements a similar set of data on 26 highly-nucleated ULIRGs presented in Paper I. Our analysis indicates that the fraction of QSOs with elliptical hosts is higher among QSOs with undetected far-infrared (FIR) emission, small infrared excess, and luminous hosts. The hosts of FIR-faint QSOs show a tendency to have less pronounced merger-induced morphological anomalies and larger QSO-to-host luminosity ratios on average than the hosts of FIR-bright QSOs, consistent with late-merger evolution from FIR-bright to FIR-faint QSOs. The spheroid sizes and total host luminosities of the radio-quiet PG QSOs in our sample are statistically indistinguishable from the ULIRG hosts presented in Paper I, while those of radio-loud PG QSOs are systematically larger and more luminous. ULIRGs and PG QSOs with elliptical hosts fall near, but not exactly on, the fundamental plane of inactive spheroids. We confirm the systematic trend noted in Paper I for objects with small (< 2 kpc) spheroids to be up to ~1 mag. brighter than inactive spheroids. The host colors and wavelength dependence of their sizes support the idea that these deviations are due at least in part to non-nuclear star formation. However, the amplitudes of these deviations does not depend on host R-H colors. Taken at face value (i.e., no correction for extinction or the presence of a young stellar population), the H-band spheroid-host luminosities imply BH masses ~5 -- 200 x 10^7 M_sun and sub-Eddington mass accretion rates for both QSOs and ULIRGs. These results are compared with published BH mass estimates derived from other methods. (abridged)

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arXiv2009

Are $^{12}$CO lines good indicators of the star formation rate in galaxies?

In this paper, we investigate the relevance of using the $^{12}$CO line emissions as indicators of star formation rates (SFR). For the first time, we present this study for a relatively large number of $^{12}$CO transitions (12) as well as over a large interval in redshift (from z$\sim$0 to z$\sim$6). For the nearby sources (D$\leq$10 Mpc), we have used homogeneous sample of $^{12}$CO data provided by Bayet et al. (2004, 2006), mixing observational and modelled line intensities. For higher-z sources (z $\geq$ 1), we have collected $^{12}$CO observations from various papers and have completed the data set of line intensities with model predictions which we also present in this paper. Finally, for increasing the statistics, we have included recent $^{12}$CO(1-0) and $^{12}$CO(3-2) observations of intermediate-z sources. Linear regressions have been calculated for identifying the tightest SFR-$^{12}$CO line luminosity relationships. We show that the \emph{total} $^{12}$CO, the $^{12}$CO(5-4), the $^{12}$CO(6-5) and the $^{12}$CO(7-6) luminosities are the best indicators of SFR (as measured by the far-infrared luminosity). Comparisons with theoretical approaches from Krumholz and Thompson (2007) and Narayanan et al. (2008) are also performed in this paper. Although in general agreement, the predictions made by these authors and the observational results we present here show small and interesting discrepancies. In particular, the slope of the linear regressions, for J$_{upper}\geq$ 4 $^{12}$CO lines are not similar between theoretical studies and observations. On one hand, a larger high-J $^{12}$CO data set of observations might help to better agree with models, increasing the statistics. On the other hand, theoretical studies extended to high redshift sources might also reduce such discrepancies.

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arXiv2009

Spitzer Quasar and ULIRG Evolution Study (QUEST). IV. Comparison of 1-Jy Ultraluminous Infrared Galaxies with Palomar-Green Quasars

We report the results from a comprehensive study of 74 ultraluminous infrared galaxies (ULIRGs) and 34 Palomar-Green (PG) quasars within z ~ 0.3$ observed with the Spitzer Infrared Spectrograph (IRS). The contribution of nuclear activity to the bolometric luminosity in these systems is quantified using six independent methods that span a range in wavelength and give consistent results within ~ +/-10-15% on average. The average derived AGN contribution in ULIRGs is ~35-40%, ranging from ~15-35% among "cool" (f_25/f_60 =< 0.2) optically classified HII-like and LINER ULIRGs to ~50 and ~75% among warm Seyfert 2 and Seyfert 1 ULIRGs, respectively. This number exceeds ~80% in PG QSOs. ULIRGs fall in one of three distinct AGN classes: (1) objects with small extinctions and large PAH equivalent widths are highly starburst-dominated; (2) systems with large extinctions and modest PAH equivalent widths have larger AGN contributions, but still tend to be starburst-dominated; and (3) ULIRGs with both small extinctions and small PAH equivalent widths host AGN that are at least as powerful as the starbursts. The AGN contributions in class 2 ULIRGs are more uncertain than in the other objects, and we cannot formally rule out the possibility that these objects represent a physically distinct type of ULIRGs. A morphological trend is seen along the sequence (1)-(2)-(3), in general agreement with the standard ULIRG - QSO evolution scenario and suggestive of a broad peak in extinction during the intermediate stages of merger evolution. However, the scatter in this sequence, implies that black hole accretion, in addition to depending on the merger phase, also has a strong chaotic/random component, as in local AGN. (abridged)

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arXiv2008

Extended silicate dust emission in PG QSOs

This paper addresses the origin of the silicate emission observed in PG QSOs, based on observations with the Spitzer Space Telescope. Scenarios based on the unified model suggest that silicate emission in AGN arises mainly from the illuminated faces of the clouds in the torus at temperatures near sublimation. However, detections of silicate emission in Type 2 QSOs, and the estimated cool dust temperatures, argue for a more extended emission region.To investigate this issue we present the mid-infrared spectra of 23 QSOs. These spectra, and especially the silicate emission features at ~10 and ~18 mu can be fitted using dusty narrow line region (NLR) models and a combination of black bodies. The bolometric luminosities of the QSOs allow us to derive the radial distances and covering factors for the silicate-emitting dust. The inferred radii are 100-200 times larger than the dust sublimation radius, much larger than the expected dimensions of the inner torus. Our QSO mid-IR spectra are consistent with the bulk of the silicate dust emission arising from the dust in the innermost parts of the NLR.

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arXiv2007

ISOCAM Mid-infrared spectroscopy and NIR photometry of the HII complex N4 in LMC

[Abridged] We present the analysis of ISOCAM-CVF and NIR photometry data of the HII region complex N4 in LMC. The aim is twofold: 1) to study the connection between the ISM and the star content of this region; 2)to investigate the effects of the lower than galactic metallicity on dust properties. A dust features -- gas lines -- continuum fitting technique on the data, allows the production of images in each single emission and the detailed analysis of dust, and ionized gas. The NIR photometry provides, for the first time, information on the stellar content of N4. The images in single dust feature bands and gas lines clearly show that the HII region core is completely devoid of the carriers responsible for the Aromatic Features (AFs). On the other hand, the ionized gas arises almost completely in this dust cavity, where also the two main exciting stars of N4 are located. We find evidences that the effect of lower than Galactic metallicity on the carriers responsible for the AFs, is not to prevent their formation or to modify their chemical properties, but to enhance their destruction by the high and hard ISRF. We show that this mechanism is more efficient on smaller dust particles/molecules thus affecting the dust-size distribution. We argue that effects on dust--size distribution, rather than thedifferent dust properties due to a lower metallicity, should be taken into account when analyzing more distant relatively low metallicity galaxies. Finally, the analysis of the stellar content of N4 reveals 7 stars: 4 reddened O MS stars and 3 stars with envelopes. In particular, one of these, seems to be an Ultra Compact HII region containing an embedded YSO.

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arXiv2006

A survey of submillimeter C and CO lines in nearby galaxies

The submillimeter CO lines are formed in warm and dense molecular gas and are therefore sensitive to the physical conditions whereas the CO (J=1-0) line is a tracer of the total molecular gas mass. In order to be able to compare the properties of molecular gas in nearby and distant galaxies, we have observed C and CO submillimeter lines (including the 12CO(6-5) and 12CO(7-6) lines) in a sample of nearby galaxies using the CSO. We have obtained a complete view of the CO cooling curve (also called CO spectral energy distribution) by combining the submillimeter CSO data with previous observations found in the literature. We made use of Large Velocity Gradient (LVG) models to analyse the observed CO cooling curve, predict CO line intensities from J=1-0 to J=15-14 in the studied galaxies, and derive the physical properties of the warm and dense molecular gas : the kinetic temperature (TK); the gas density (n(H2)); the N(12CO)/$Δv$. The predictions for the line intensities and for the total CO cooling power, obtained from LVG modelling have been compared with predictions from Photo Dissociation Regions (PDR) models. We show how the CO SED varies according to the galaxy star forming activity. For active nuclei, the peak is located near the 12CO(6-5) or 12CO(7-6) rotational lines, while, for normal nuclei, most of the energy is carried by the 12CO(4-3) and 12CO(5-4) lines. Whatever the spectral type of the nucleus, the observed C cooling rate is lower than the observed CO cooling rate (by a factor of around 4). The CO cooling curve of nearby starburst galaxies (e.g. NGC 253) has a quite similar shape to the CO cooling curve of distant galaxies. Therefore, the CO cooling curves are useful diagnostics for the star forming activity in distant objects.

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arXiv2006

Mid-Infrared Diagnostics of LINERs

We report results from the first mid-infrared spectroscopic study of a comprehensive sample of 33 LINERs, observed with the Spitzer Space Telescope. We compare the properties of two different LINER populations: infrared-faint LINERs, with LINER emission arising mostly in compact nuclear regions, and infrared-luminous LINERs, which often show spatially extended (non-AGN) LINER emission. We show that these two populations can be easily distinguished by their mid-infrared spectra in three different ways: (i) their mid-IR spectral energy distributions (SEDs), (ii) the emission features of polycyclic aromatic hydrocarbons (PAHs), and (iii) various combinations of IR fine-structure line ratios. IR-luminous LINERs show mid-IR SEDs typical of starburst galaxies, while the mid-IR SEDs of IR-faint LINERs are much bluer. PAH flux ratios are significantly different in the two groups. Fine structure emission lines from highly excited gas, such as [O IV], are detected in both populations, suggesting the presence of an additional AGN also in a large fraction of IR-bright LINERs, which contributes little to the combined mid-IR light. The two LINER groups occupy different regions of mid-infrared emission-line excitation diagrams. The positions of the various LINER types in our diagnostic diagrams provide important clues regarding the power source of each LINER type. Most of these mid-infrared diagnostics can be applied at low spectral resolution, making AGN- and starburst-excited LINERs distinguishable also at high redshifts.

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arXiv2006

Spitzer Quasar and ULIRG evolution study (QUEST): I. The origin of the far infrared continuum of QSOs

This paper addresses the origin of the far-infrared (FIR) continuum of QSOs, based on the Quasar and ULIRG Evolution Study (QUEST) of nearby QSOs and ULIRGs using observations with the Spitzer Space Telescope. For 27 Palomar-Green QSOs at z <~ 0.3, we derive luminosities of diagnostic lines ([NeII]12.8um, [NeV]14.3um, [OIV]25.9um) and emission features (PAH7.7um emission which is related to star formation), as well as continuum luminosities over a range of mid- to far-infrared wavelengths between 6 and 60um. We detect star-formation related PAH emission in 11/26 QSOs and fine-structure line emission in all of them, often in multiple lines. The detection of PAHs in the average spectrum of sources which lack individual PAH detections provides further evidence for the widespread presence of PAHs in QSOs. Similar PAH/FIR and [NeII]/FIR ratios are found in QSOs and in starburst-dominated ULIRGs and lower luminosity starbursts. We conclude that the typical QSO in our sample has at least 30% but likely most of the far-infrared luminosity (~ 10^(10...12)Lsun) arising from star formation, with a tendency for larger star formation contribution at the largest FIR luminosities. In the QSO sample, we find correlations between most of the quantities studied including combinations of AGN tracers and starburst tracers. The common scaling of AGN and starburst luminosities (and fluxes) is evidence for a starburst-AGN connection in luminous AGN. Strong correlations of far-infrared continuum and starburst related quantities (PAH, low excitation [NeII]) offer additional support for the starburst origin of far-infrared emission.

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arXiv2005

Silicate emissions in active galaxies - From LINERs to QSOs

We report the first detection of ~10 and ~18 micron silicate dust emissions in a low-luminosity active galactic nucleus (AGN), obtained in Spitzer-IRS 7-37 micron spectroscopy of the Type 1 LINER galaxy NGC3998. Silicate emissions in AGN have only recently been detected in several quasars. Our detection counters suggestions that silicate emissions are present only in the most luminous AGN. The silicate features may be signatures of a dusty ``obscuring torus'' viewed face-on as postulated for Type 1 AGN. However, the apparently cool (~200 K) dust is inconsistent with theoretical expectations of much hotter torus walls. Furthermore, not all Type 1 objects are silicate emission sources. Alternatively, the silicate emission may originate in dust not directly associated with a torus. We find that the long-wavelength (>20 micron) tail of the emission in NGC3998 is significantly weaker than in the sample of bright QSOs recently presented by Hao et al. The 10 micron profile in our NGC3998 spectrum is inconsistent with ``standard'' silicate ISM dust. This may indicate differences in the dust composition, grain size distribution, or degree of crystallization. The differences between NGC3998, QSOs, and Galactic templates suggest that there are significant environmental variations.

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arXiv2004

The submillimeter C and CO lines in Henize 2-10 and NGC 253

The purpose of this paper is to describe a method for determining a cooling template for galaxies, using nearby galaxies, and applicable to future observations of distant galaxies. We observed two starburst galaxies (NGC 253 and Henize 2-10) with the Caltech Submillimeter Observatory in the rotational lines of carbon monoxide 12CO(J=3-2), (J=6-5) and (J=7-6) for both, and also 12CO(J=4-3) and 13CO(J=3-2) for Henize 2-10 and in the 3P2-3P1 fine-structure transitions of atomic carbon [CI] at 809 GHz for NGC 253. Some of these observations have been made previously, but the present multitransition study (including data found in the literature) is the most complete to date for the two galaxies. From these observations, we have derived the properties of the warm and dense molecular gas in the galaxy nuclei. We used an LTE analysis and an LVG radiative transfer model to determine physical conditions of the interstellar medium in both sources and predicted integrated line properties of all CO transitions up to 12CO(15-14). A PDR model has also been used and here the data are well fitted (within 20 %) by a model cloud with a gas density of n(H)= 8.0 +- 1.0 * 10E5 cm-3 and an incident FUV flux of chi = 20000 for Henize 2-10. For NGC 253, we deduced n(H) = 3.0 +- 0.5 * 10E5 cm-3 and chi = 20000 for the modelled cloud. The physical properties of warm gas and CO cooling curves of the target galaxies are compared with those measured for the nucleus of the Milky Way and the Cloverleaf QSO. The gas properties and CO cooling curve are similar for the two starburst galaxies and the Cloverleaf QSO while the Milky Way nucleus exhibits lower excitation molecular gas.

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arXiv2002

ISO--LWS observations of the two nearby spiral galaxies: NGC6946 and NGC1313

(Abridged) We present the analysis of the main FIR fine structure lines emission in NGC1313 and NGC6946. We calculate that a component probably associated with the diffuse disks contributes <~40% in N6946 and ~30 % in N1313 to the total [CII] emission. The main PDR physical parameters responsible for the neutral atomic gas emission in N1313 and N6946 do not significantly differ from what Malhotra etal (2001) found by modelling the integrated emission of a sample of 60 normal galaxies,although there are evidences for a beam averaged contribution of a less active component inside NGC6946 higher than its contribution in the integrated emission of normal galaxies. CO and [CII] in N6946 are well correlated with a mean [CII]/CO ratio similar to that of the normal galaxies sample. In N1313 the [CII]/CO seems to systematically increase from the North to the south, along the S-shaped spiral arm, indicating much more inhomogeneous conditions than in N6946. HI and [CII] in N6946 are completely de-correlated, probably because they arise from different gas components. In N1313 we successfully detect two distinct gas components: a cirrus-like component where HI and [CII] are weakly correlated as observed in our Galaxy, and a component associated with dense PDRs completely de-correlated from HI as observed in N6946.Finally, we find that the HI residing in dense PDRs and presumably recently photo-dissociated, constitutes a few % of the total HI. In turn, this dense gas component produces most of the [CII] emission emitted by the atomic neutral medium.

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arXiv2001

Far Infrared Spectroscopy of Normal Galaxies: Physical Conditions in the Interstellar Medium

The most important cooling lines of the neutral interstellar medium (ISM) lie in the far-infrared (FIR). We present measurements by the Infrared Space Observatory Long Wavelength Spectrometer of seven lines from neutral and ionized ISM of 60 normal, star-forming galaxies. The galaxy sample spans a range in properties such as morphology, FIR colors (indicating dust temperature), and FIR/Blue ratios (indicating star-formation activity and optical depth). In two-thirds of the galaxies in this sample, the [CII] line is proportional to FIR dust continuum. The other one-third show a smooth decline in [CII]/FIR with increasing F60/F100 and FIR/B, spanning a range of a factor of more than 50. Two galaxies, at the warm and active extreme of the range have [CII]/FIR < 2 \times 10^{-4} (3-sigma upper limit). This is due to increased positive grain charge in the warmer and more active galaxies, which leads to less efficient heating by photoelectrons from dust grains. The ratio of the two principal photodissociation region (PDR) cooling lines [CII]/[OI] shows a tight correlation with F60/F100, indicating that both gas and dust temperatures increase together. We derive a theoretical scaling between [NII] and [CII] from ionized gas and use it to separate [CII] emission from neutral PDRs and ionized gas. Comparison of PDR models of Kaufman et al. (1999) with observed ratios of (a) [OI]/[CII] and ([CII]+[OI])/FIR and (b) [OI]/FIR and F60/F100 yields far-UV flux G0 and gas density n. The derived G0 scales as n to the power 1.4. We interpret this correlation as arising from Stromgren sphere scalings if much of the line and continuum luminosity arises near star-forming regions. The differences in G0 and n may be due to differences in the physical properties of the star-forming clouds.(Short abstract)

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arXiv2000

The Interstellar Medium of Star-forming Irregular Galaxies: The View with ISO

We present mid-infrared imaging and far-infrared (FIR) spectroscopy of 5 IBm galaxies observed by ISO as part of our larger study of the inter- stellar medium of galaxies. Most of the irregulars in our sample are very actively forming stars. The mid-infrared imaging was in a band centered at 6.75 microns that is dominated by polycyclic aromatic hydrocarbons (PAHs) and in a band centered at 15 microns that is dominated by small dust grains. The spectroscopy of 3 of the galaxies includes [CII]158 microns and [OI]63 microns, important coolants of photodissociation regions (PDRs), and [OIII]88 microns and [NII]122 microns, which come from ionized gas. [OI]145 microns and [OIII]52 microns were measured in one galaxy as well. These data are combined with PDR and HII region models to deduce properties of the interstellar medium of these galaxies.

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