The [C II] 158 Micron Line Deficit in Ultraluminous Infrared Galaxies Revisited

By M. Luhman, S. Satyapal, J. Fischer, M. Wolfire, E. Sturm, C. Dudley, D. Lutz, R. Genzel. 2003

179 citations recorded by the source corpus.

We present a study of the [C II] 157.74 μm fine-structure line in a sample of 15 ultraluminous infrared (IR) galaxies (IR luminosity LIR ⩾ 1012 L☉; ULIRGs) using the Long Wavelength Spectrometer (LWS) on the Infrared Space Observatory (ISO). We confirm the observed order of magnitude deficit (compared to normal and starburst galaxies) in the strength of the [C II] line relative to the far-infrared (FIR) dust continuum emission found in our initial report, but here with a sample that is twice as large. This result suggests that the deficit is a general phenomenon affecting 4 out of 5 ULIRGs. We present an analysis using observations of generally acknowledged photodissociation region (PDR) tracers ([C II], [O I] 63 and 145 μm, and FIR continuum emission), which suggests that a high ultraviolet flux G0 incident on a moderate density n PDR could explain the deficit. However, comparisons with other ULIRG observations, including CO (1-0), [C I] (1-0), and 6.2 μm polycyclic aromatic hydrocarbon (PAH) emission, suggest that high G0/n PDRs alone cannot produce a self-consistent solution that is compatible with all of the observations. We propose that non-PDR contributions to the FIR continuum can explain the apparent [C II] deficiency. Here, unusually high G0 and/or n physical conditions in ULIRGs as compared to those in normal and starburst galaxies are not required to explain the [C II] deficit. Dust-bounded photoionization regions, which generate much of the FIR emission but do not contribute significant [C II] emission, offer one possible physical origin for this additional non-PDR component. Such environments may also contribute to the observed suppression of FIR fine-structure emission from ionized gas and PAHs, as well as the warmer FIR colors found in ULIRGs. The implications for observations at higher redshifts are also revisited.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/b7d006d4b6278339ccbb7053b75c7a1fd625c1b4

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Citations in the corpus

• OBSERVATIONS OF Arp 220 USING HERSCHEL-SPIRE: AN UNPRECEDENTED VIEW OF THE MOLECULAR GAS IN AN EXTREME STAR FORMATION ENVIRONMENT (2011, unknown): “Their modeling results suggest that the line deficit in H II regions is the result of a higher ionization parameter in ULIRGs compared to normal or starburst galaxies.”
• The Star Formation Rate and Dense Molecular Gas in Galaxies (2003, background): “However, it has become clear that [C II] is underluminous in ULIGs (e.g., Luhman et al. 2003) and is not a consistent star formation indicator.”
• The Herschel Dwarf Galaxy Survey - I. Properties of the low-metallicity ISM from PACS spectroscopy (2015, background): “A deficit in the FIR line intensities is, however, found in luminous IR galaxies (e.g., Luhman et al. 2003; Graciá-Carpio et al. 2011; Croxall et al. 2012; Díaz-Santos et al. 2013).”
• Dusty Star Forming Galaxies at High Redshift (2014, background): “However, present-epoch ULIRGs emit roughly ∼10% of the expected [CII] flux, given their far infrared luminosities (e.g. Malhotra et al., 1997, 2001; Luhman et al., 1998, 2003).”
• STAR FORMATION AND GAS KINEMATICS OF QUASAR HOST GALAXIES AT z ∼ 6: NEW INSIGHTS FROM ALMA (2013, methodology): “We compare them to samples of [C ii]-detected local normal star forming galaxies, ULIRGs, submillimeter galaxies, and FIR-luminous quasars at high redshift (Malhotra et al. 2001; Luhman et al. 2003; Stacey et al. 2010; Maiolino et al. 2009; Ivison et al. 2010; De Breuck et al. 2011; Swinbank et al. ”
• Cool Gas in High-Redshift Galaxies (2013, result): “This explanation is supported by the fact that the [C II]/FIR ratio is also a decreasing function of increasing dust temperature (e.g., Malhotra et al. 2001, Luhman et al. 2003).”
• The applicability of far-infrared fine-structure lines as star formation rate tracers over wide ranges of metallicities and galaxy types (2014, background): “On top of this, deficits in the [C]/FIR ratio toward warm dust temperatures (Crawford et al. 1985; Stacey et al. 1991; Malhotra et al. 1997, 2001; Luhman et al. 2003; Verma et al. 2005; Brauher et al. 2008; Graciá-Carpio et al. 2011; Croxall et al. 2012; Díaz-Santos et al. 2013; Farrah et al. 2013)…”
• First detection of [CII]158 μm at high redshift : vigorous star formation in the early universe (2005, background): “For sources with far-infrared luminosities in excess of 1012 L⊙ or with increasing star formation activity, this ratio drops by an order of magnitude (Malhotra et al., 2001; Luhman et al., 1998, 2003; Negishi et al., 2001).”
• A Herschel/PACS Far-infrared Line Emission Survey of Local Luminous Infrared Galaxies (2017, background): “There are 180 LIRGs and 22 ULIRGs in GOALS and their median redshift is z = 0.0215 (or ∼ 95.2Mpc), with the closest galaxy being at z = 0.0030 (15.9Mpc; NGC 2146) and the farthest at z = 0.0918 (400Mpc; IRAS 07251- 0248).”
• A 158 μm [C ii] LINE SURVEY OF GALAXIES AT z ∼ 1–2: AN INDICATOR OF STAR FORMATION IN THE EARLY UNIVERSE (2010, background): “The observed R for the AGN-dominated systems within our sample is very similar to that of local ULIRG galaxies (Luhman et al. 2003).”
• Very extended cold gas, star formation and outflows in the halo of a bright QSO at z>6 (2014, background): “…gas heating via photoelectrons released by dust grains and so the relative efficiency of cooling via [C ii] emission with respect to dust cooling (Luhman et al. 2003; Díaz-Santos et al. 2013); (iii) a high ionisation parameter U (which is essentially linked to (ii)) that reduces the opacity of…”
• A Compendium of Far-Infrared Line and Continuum Emission for 227 Galaxies Observed by the Infrared Space Observatory (2008, background): “The properties of these emission lines are compared to findings from previous LWS emission line studies (Malhotra et al. 1997, 2001; Leech et al. 1999; Fischer et al. 1999; Luhman et al. 1998; Negishi et al. 2001; Luhman et al. 2003).”
• Polycyclic Aromatic Hydrocarbons as a Tracer of Star Formation? (2004, background): “In that respect, we note that the PDR fine-structure lines are very weak in Arp 220 and other ULIRGs (Luhman et al. 2003; Dale et al. 2004), suggesting also that the PDR component is underdeveloped, perhaps as a result of absorption of a major fraction of the FUV flux by dust inside the H ii region…”