High-Resolution Mid-Infrared Spectroscopy of Ultraluminous Infrared Galaxies

By D. Farrah, Jeronimo Bernard-Salas, H. Spoon, B. Soifer, Lee Armus, B. Brandl, Vassilis Charmandaris, Vandana Desai, S. Higdon, D. Devost and 1 more. 2007

223 citations recorded by the source corpus.

We present R ~ 600, 10-37 μm spectra of 53 ultraluminous infrared galaxies (ULIRGs), taken using the Infrared Spectrograph on board Spitzer. The spectra show fine-structure emission lines of neon, oxygen, sulfur, silicon, argon, chlorine, iron, and phosphorous; molecular hydrogen lines, and C2H2, HCN, and OH- absorption features. We employ diagnostics based on the fine-structure lines, the polycyclic aromatic hydrocarbon (PAH) features and the 9.7 μm silicate absorption feature, to show that the infrared emission from most ULIRGs is powered mostly by star formation, with only ~20% of ULIRGs hosting an AGN with a greater IR luminosity than the starburst. The detection of [Ne V] λ14.32 in just under half the sample, however, implies that an AGN contributes significantly to the mid-IR flux in ~42% of ULIRGs. The starbursts and AGNs in ULIRGs appear more extincted, and for the starbursts more compact than those in lower luminosity systems. The excitations and electron densities in the narrow-line regions of ULIRGs appear comparable to those of starbursts with L≲1011.5 L☉, although the NLR gas in ULIRGs may be more dense. We show that the [Ne II] λ12.81 + [Ne III] λ15.56 luminosity correlates with both infrared luminosity and the luminosity of the 6.2 and 11.2 μm PAH features, and derive a calibration between PAH luminosity and star formation rate. Finally, we show that ULIRGs with silicate absorption strengths Ssil of 0.8 ≲ Ssil ≲ 2.4 are likely to be powered mainly by star formation, but that ULIRGs with Ssil ≲ 0.8, and possibly those with Ssil ≳ 2.4, contain an IR-luminous AGN.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/4c051cccb8a967fcc07273dae764cbdac620c7dd

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

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

Citations in the corpus

• SPITZER QUASAR AND ULIRG EVOLUTION STUDY (QUEST). IV. COMPARISON OF 1 Jy ULTRALUMINOUS INFRARED GALAXIES WITH PALOMAR-GREEN QUASARS (2009, background): “…(GTO and GO) programs have provided a wealth of new information on the physical properties of local ULIRGs (e.g., Armus et al. 2004, 2007; Farrah et al. 2007; Desai et al. 2007; Hao et al. 2007; Higdon et al. 2006; Imanishi et al. 2007; Lahuis et al. 2007; Spoon et al. 2007; CAo et al.…”
• The Herschel census of infrared SEDs through cosmic time (2013, background): “…to be less compact than their local counterparts (e.g. Tacconi et al. 2006; Iono et al. 2009; Rujopakarn et al. 2011), exhibiting stronger PAH emission (Farrah et al. 2007, 2008; Valiante et al. 2007) and a greater abundance of cold dust (Kovács et al. 2006; Pope et al. 2006; Coppin et al. 2008).”
• Towards a complete census of AGN in nearby Galaxies: a large population of optically unidentified AGN (2009, background): “Previous surveys (e.g., Farrah et al. 2007; Groves et al. 2008; Meléndez et al. 2008) have selected potential AGNs on the basis of high [NeIII]–[NeII] flux ratios The Ubiquity of AGN Activity in the local Universe 19 ([NeIII]/[NeII]> 1.03; Meléndez et al. 2008).”
• MASSIVE MOLECULAR OUTFLOWS AND NEGATIVE FEEDBACK IN ULIRGs OBSERVED BY HERSCHEL-PACS (2011, methodology): “For IRAS13120-5453 and IRAS14378-3651 (which are not part of V09) we calculated AGN fractions using method 1 from V09, based on the observed [O IV]/[Ne II] ratio (and the observed upper limit for IRAS14378-3651) from Farrah et al. (2007).”
• THE ROLE OF STARBURST–ACTIVE GALACTIC NUCLEUS COMPOSITES IN LUMINOUS INFRARED GALAXY MERGERS: INSIGHTS FROM THE NEW OPTICAL CLASSIFICATION SCHEME (2009, background): “Although numerous studies at various wavelengths continue to be carried out to determine the energy source of ULIRGs (e.g., Tran et al. 2001; Farrah et al. 2003, 2007; Lı́pari et al. 2003; Ptak et al. 2003; Imanishi et al. 2007), determining the relative contribution of starbursts and AGN within…”
• Galaxy pairs in the Sloan Digital Sky Survey – IX. Merger-induced AGN activity as traced by the Wide-field Infrared Survey Explorer (2014, background): “…been a number of mid-infrared studies of interacting galaxies, virtually all past studies have employed small samples of galaxies and/or have targeted the most advanced stage mergers (e.g., Genzel et al. 1998; Veilleux et al. 2009; Armus et al. 2007, 2009; Farrah et al. 2007; Petric et al. 2011).”
• DUST-CORRECTED STAR FORMATION RATES OF GALAXIES. I. COMBINATIONS OF Hα AND INFRARED TRACERS (2009, methodology): “…TIR emission sufficiently so that it (or neighboring regions observed with the Infrared Space Observatory (ISO)) has been calibrated as an IR SFR tracer of its own (e.g., Roussel et al. 2001; Boselli et al. 2004; Förster Schreiber et al. 2004; Wu et al. 2005; Farrah et al. 2007; Zhu et al. 2008).”
• Ionized gas outflows and global kinematics of low-z luminous star-forming galaxies (2014, background): “%) having signatures of an AGN (Armus et al. 2007, Desai et al. 2007, Farrah et al. 2007), with about 20% - 40% dominated by the AGN (at least at mid-IR wavelengths).”
• GALAXY AND MASS ASSEMBLY (GAMA): MID-INFRARED PROPERTIES AND EMPIRICAL RELATIONS FROM WISE (2014, background): “As first demonstrated with Spitzer measurements (see for example Houck et al. 2007; Farrah et al. 2007), PAHs can be used to estimate star formation, although there is larger scatter (and potential biases) relative to the superior 24 μm mid-infrared or 70 μm far-infrared tracers.”
• The applicability of far-infrared fine-structure lines as star formation rate tracers over wide ranges of metallicities and galaxy types (2014, methodology): “While we rely on the TIR luminosity and the SFR(TIR) calibration presented in Hao et al. (2011), Farrah et al. (2013) use the PAH luminosity and the SFR(PAH) relation presented in Farrah et al. (2007).”
• C-GOALS: Chandra observations of a complete sample of luminous infrared galaxies from the IRAS Revised Bright Galaxy Survey (2011, methodology): “The infrared SED is considered to be powered primarily by the AGN (e.g. van der Werf et al. 2010), but note that mid-IR [NeV] is not detected (Farrah et al 2007).”
• Star Formation in the Milky Way and Nearby Galaxies (2012, background): “…the SFR in metalrich luminous star-forming galaxies (e.g., Roussel et al. 2001; Peeters et al. 2004; Förster Schreiber et al. 2004; Wu et al. 2005a; Farrah et al. 2007; Calzetti et al. 2007), but the PAH bands weaken dramatically below metal abundances of approximately 1/4 to 1/3 Z⊙ (e.g., Madden…”
• Dusty Star Forming Galaxies at High Redshift (2014, background): “It follows that PAH emission strength scales with star formation rate (which relies on the assumption that stellar emission heats the photo-dissociation regions where the PAHs reside Farrah et al., 2007).”
• Luminous Infrared Galaxies with the Submillimeter Array. I. Survey Overview and the Central Gas to Dust Ratio (2008, background): “The [NeV] line, which is an indicator of an AGN, is not detected in this galaxy (Farrah et al. 2007).”
• Modeling the Pan-Spectral Energy Distribution of Starburst Galaxies. IV. The Controlling Parameters of the Starburst SED (2007, result): “In this way, it should assist in the derivation of statistical parameters, demography and cosmic evolution of this class of object, and should cast light on the nature of starbursts in the high redshift universe, including sub-mm galaxies and the high-redshift radio galaxies, when today’s massive “r”
• Mid-Infrared Spectral Diagnosis of Submillimeter Galaxies (2007, methodology): “Armus et al. (2007) presented IRS spectroscopy of 10 ULIRGs from the Bright Galaxy Sample (BGS; S60 > 5:4mJy; Soifer et al. 1987), and the IRS spectra for a sample of over 100 ULIRGs were recently presented in Desai et al. (2007) and Farrah et al. (2007).”
• THE MULTIPHASE STRUCTURE AND POWER SOURCES OF GALACTIC WINDS IN MAJOR MERGERS (2013, background): “120 pc; Downes & Solomon 1998), and is the source of most of the MIR luminosity (Soifer et al. 2000).”