ISOCAM-CVF 5-12 Micron Spectroscopy of Ultraluminous Infrared Galaxies

By Q. D. Tran, D. Lutz, R. Genzel, D. Rigopoulou, H. Spoon, E. Sturm, M. Gerin, D. Hines, A. Moorwood, D. Sanders and 4 more. 2001

176 citations recorded by the source corpus.

We present low-resolution mid-infrared (MIR) spectra of 16 ultraluminous infrared galaxies (ULIRGs) obtained with the circular variable filter (CVF) spectroscopy mode of ISOCAM on board the Infrared Space Observatory (ISO). Our sample completes previous ISO spectroscopy of ultra- and hyperluminous infrared galaxies toward higher luminosities. The combined samples cover an infrared luminosity range of ~1012-1013.1 L☉. To discriminate active galactic nucleus (AGN) and starburst activity, we use the AGN-related MIR continuum and the starburst-related 6.2, 7.7, 8.6, and 11.3 μm MIR emission bands attributed to aromatic carbonaceous material. For about half of the high-luminosity ULIRGs studied here, strong aromatic emission bands suggest starburst dominance. Other spectra are dominated by a strong AGN-related continuum with weak superposed emission features of uncertain nature. Our sample contains one unusual example, IRAS F00183-7111, of an AGN that is highly obscured even in the MIR. An improved method to characterize quantitatively the relative contribution of star formation and AGN activity to the MIR emission of ULIRGs is presented. The ULIRG spectra are fitted by a superposition of a starburst and an AGN spectrum, both of which may be obscured at different levels. Models in which starburst and AGN obscuration differ are significantly more successful than models with a single extinction. Previous results based on a simpler line-to-continuum measure of aromatic emission strength are confirmed, further supporting the robustness of the aromatic emission feature as a diagnostic of ULIRG power sources. As dominant sources of the bolometric luminosity, starbursts prevail at the lower end and AGNs at the higher end of this range. The transition between mostly starburst and mostly AGN powered occurs at ~1012.4-1012.5 L☉, and individual luminous starbursts are found up to ~1012.65 L☉.

Subfields: Astronomy and Astrophysics

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7. R. Dav'e
8. R. Genzel

Citations in the corpus

• Optical and Near-Infrared Imaging of the IRAS 1 Jy Sample of Ultraluminous Infrared Galaxies. II. The Analysis (2002, result): “These results are compatible with those from recent mid-infrared spectroscopic surveys carried out with ISO (e.g., Genzel et al. 1998; Lutz et al. 1998; Rigopoulou et al. 1999; Tran et al. 2001).”
• The [C II] 158 Micron Line Deficit in Ultraluminous Infrared Galaxies Revisited (2003, background): “…Arp 220, and modeled the photoionization of dust-bounded nebulae; and Genzel et al. (1998), Lutz et al. (1998), Rigopoulou et al. (1999), Dudley (1999), Tran et al. (2001), and C. C. Dudley et al. (in preparation) studied the polycyclic aromatic hydrocarbon (PAH) emission in luminous IR galaxies.”
• The relation between AGN hard X-ray emission and mid-infrared continuum from ISO spectra: Scatter and unification aspects , (2004, background): “A full spectral decomposition accounting for all these effects can be attempted in cases of good signal-to-noise ratio and full wavelength coverage (e.g. Tran et al. 2001; Spoon et al. 2004).”
• Starburst and AGN activity in ultraluminous infrared galaxies (2003, methodology): “Other infrared data were taken from Carico et al (1988); Maiolino et al (1995); Klaas et al (1997); Rigopoulou et al (1999); Dale et al (2000); Zink et al (2000); Tran et al (2001) & Klaas et al (2001).”
• High-Resolution Mid-Infrared Spectroscopy of Ultraluminous Infrared Galaxies (2007, background): “…et al. 2003; Farrah et al. 2005), mid-infared spec- troscopy (Lutz et al. 1996, 1998; Genzel et al. 1998; Rigopoulou et al. 1999; Genzel &Cesarsky 2000; Tran et al. 2001), modeling of their 1Y1000 m spectral energy distributions (Klaas et al. 2001; Farrah et al. 2003), and X-ray observations…”
• Polycyclic Aromatic Hydrocarbons as a Tracer of Star Formation? (2004, background): “…that PAH emission features in extragalactic environments are very similar to those in Galactic star-forming regions (e.g., Genzel et al. 1998; Lutz et al. 1998; Mirabel et al. 1998; Charmandaris et al. 986 1999; Rigopoulou et al. 1999; Clavel et al. 2000; Helou et al. 2000; Tran et al. 2001).”
• The Detection of Silicate Emission from Quasars at 10 and 18 Microns (2005, background): “…absorption is also detected in dusty starburst galaxies (Rigopoulou et al. 1999), ultraluminous infrared galaxies (ULIRGs; Genzel et al. 1998; Tran et al. 2001; Spoon et al. 2004; Armus et al. 2004), and a sample of mid-infrared detected, optically invisible, high-luminosity galaxies with…”
• Infrared Luminosity Functions from the Chandra Deep Field-South: The Spitzer View on the History of Dusty Star Formation at 0 ≲ z ≲ 1* (2005, background): “In the local Universe moreover, AGNs dominate the mid-IR output of galaxies only for the most extreme ULIRGs (e.g., Lutz et al. 1998; Tran et al. 2001), while the X-ray and optical spectral properties of infrared galaxies detected with ISO and MIPS at 15µm and 24µm also argue for a population…”
• Interpreting the Cosmic Infrared Background: Constraints on the Evolution of the Dust-enshrouded Star Formation Rate (2001, methodology): “44 spiral and starburst galaxies had photometry from ISOCAM (Chanial et al. 2001; Roussel et al. 2001; Laurent et al. 2000), 8 ULIGs had spectra from ISOCAM circular variable filters (CVF) observations (Tran et al. 2001) while 37 ULIGs had ISOPHOT mid-infrared spectra (Rigopoulou et al. 1999).”
• The X-Ray Spectral Properties of SCUBA Galaxies (2005, background): “…the threshold between the AGN- and star formation–dominated literature galaxies is LX/LFIR 0:004; of the 35 galaxies in Rigopoulou et al. (1999) and Tran et al. (2001), all of the 17 AGN-dominated galaxies have LX/LFIR > 0:004, while 13 of the 18 star formation–dominated galaxies have LX/LFIR <…”
• A long-wavelength view on galaxy evolution from deep surveys by the Infrared Space Observatory (2001, background): “Tran et al. (2001) consistently find that the contribution of gravitational accretion to the IR emission by local ULIRGs becomes important, or even dominant, only in the very high luminosity regime (Lbol > 10 12.4 L⊙).”
• Mid-Infrared Spectra of Classical AGNs Observed with the Spitzer Space Telescope (2005, background): “By providing a variety of AGN ”templates”, we can increase the ability to divide any given source into AGN and starburst components (e.g. Tran et al. (2001), Farrah et al. (2003)).”
• What drives the growth of black holes (2011, background): “At higher LIR the fraction of the luminosity from the AGN increases, and the large masses of nuclear gas and dust ensure that much of the BH growth is observed to be heavily obscured (e.g., Tran et al., 2001; Yuan et al., 2010; Iwasawa et al., 2011; Petric et al., 2011b).”
• SPITZER QUASAR AND ULIRG EVOLUTION STUDY (QUEST). IV. COMPARISON OF 1 Jy ULTRALUMINOUS INFRARED GALAXIES WITH PALOMAR-GREEN QUASARS (2009, methodology): “ULIRGs with log[L(IR)/L⊙] ≥ 12.4 have slightly smaller 7.7µm PAH equivalent widths than lower luminosity objects (–0.36 ± 0.09 vs. 0.04 ± 0.08; Figure 21b), in agreement with earlier ISO results (e.g., Lutz et al. 1998b; Tran et al. 2001).”
• STRUCTURE AND FORMATION OF ELLIPTICAL AND SPHEROIDAL GALAXIES (2008, background): “AGNs are seen to be more important in more luminous ULIRGs (Lutz et al. 1998; Genzel et al. 2000; Tran et al. 2001; Farrah et al. 2002; Veilleux et al. 2006; Schweitzer et al. 2006; Netzer et al. 200).”
• 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…”
• Detection of the Buried Active Galactic Nucleus in NGC 6240 with the Infrared Spectrograph on the Spitzer Space Telescope (2005, unknown): “Spectroscopic observations with the ISO satellite greatly expanded our understanding of the mid-infrared spectra of ULIRGs (e.g., Genzel et al. 1998; Lutz et al. 1999; Rigopoulou et al. 1999; Spoon et al. 2002; Sturm et al. 2002; Tran et al. 2001).”
• A Redshift Survey of the Submillimeter Galaxy Population (2004, methodology): “Mid-IR spectral surveys with ISO (Lutz et al. 1999; Tran et al. 2001) demonstrated that this wavelength regime is a powerful tool to classify the energetics of galaxies in an independent manner from conventional optical classification techniques (e.g., Swinbank et al. 2004).”
• Defining the intrinsic AGN infrared spectral energy distribution and measuring its contribution to the infrared output of composite galaxies (2011, background): “…would therefore provide a measure of the levels of AGN and star-formation activity that islargely unaffected by obscuration or absorption; similar, in principle, to the infrared spectral decompositions carried out by, for example, Laurent et al. (2000),Tran et al. (2001) and Lutz et al. (2004).”