Starburst and AGN activity in ultraluminous infrared galaxies

By D. Farrah, J. Afonso, A. Efstathiou, M. Rowan‐Robinson, M. Fox, D. Clements. 2003

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We examine the power source of 41 local Ultraluminous Infrared Galaxies (ULIRGs) using archival infrared (IR) and optical photometry. We fit the observed Spectral Energy Distributions (SEDs) with starburst and AGN components; each component being drawn from a family of templates. We find all of the sample require a starburst, whereas only half require an AGN. In 90% of the sample the starburst provides over half the IR emission, with a mean fractional luminosity of 82%. When combined with other galaxy samples we find that starburst and AGN luminosities correlate over 6 decades in IR luminosity suggesting that a common factor governs both luminosities, plausibly the gas masses in the nuclear regions. We find no trend for increasing fractional AGN luminosity with increasing total luminosity, contrary to previous claims. We find that the mid-IR F7.7/C7.7 line-continuum ratio is no indication of the starburst luminosity, or the fractional AGN luminosity, and therefore that F7.7/C7.7 is not a reliable diagnostic of the power source in ULIRGs. The radio flux correlates with the starburst luminosity, but shows no correlation with the AGN luminosity, in line with previous results. We propose that the scatter in this correlation is due to a skewed starburst IMF and/or relic relativistic electrons from a previous starburst, rather than contamination from an obscured AGN. We show that most ULIRGs undergo multiple starbursts during their lifetime, and by inference that mergers between more than two galaxies may be common amongst ULIRGs. Our results support the evolutionary model for ULIRGs proposed by Farrah et al (2001), where they can follow many different evolutionary paths of starburst and AGN activity in transforming merging spiral galaxies into elliptical galaxies, but that most do not go through an optical QSO phase. The lower level of AGN activity in our local sample than in z � 1 HLIRGs implies that the two samples are distinct populations. We postulate that different galaxy formation processes at high-z are responsible for this difference.

Subfields: Astronomy and Astrophysics, Electrical and Electronic Engineering, Instrumentation

View Paper: https://www.semanticscholar.org/paper/6e696833db180817bb541b7834266fc3c5c0095a

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Citations in the corpus

• 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…”
• The multi-phase winds of Markarian 231: from the hot, nuclear, ultra-fast wind to the galaxy-scale, molecular outflow (2015, background): “The bolometric luminosity estimated by Lonsdale et al. (2003) and Farrah et al. (2003) is 5× 1045 erg s−1.”
• The X-Ray Spectral Properties of SCUBA Galaxies (2005, result): “However, since different techniques often yield contrasting results (e.g., Farrah et al. 2003) and the exact contributions from AGN and star formation activity are uncertain even in extremely well-studied local galaxies (e.g., Spoon et al. 2000; Lutz et al. 2003; Iwasawa et al. 2005b), this…”
• The Herschel census of infrared SEDs through cosmic time (2013, background): “They hide an immensely active interstellar medium (e.g. Lutz et al. 1998; Farrah et al. 2003; Narayanan et al. 2005; Sturm et al. 2010) and are the ultimate stellar nurseries, with star-formation rates (SFRs) up to a few thousand times higher than Milky Way-type galaxies (e.g. Kennicutt 1998; Egami…”
• Infrared Power-Law Galaxies in the Chandra Deep Field-South: Active Galactic Nuclei and Ultraluminous Infrared Galaxies (2006, methodology): “In addition to the data from NED, we have made use of ISO data for non-AGN LIRGs from Lu et al. (2003) and for cool ULIRGs from Farrah et al. (2003), as well as optical and near-IR data from Surace et al. (2000).”
• Spitzer Power-Law Active Galactic Nucleus Candidates in the Chandra Deep Field-North (2007, background): “Arp 220 and IRAS 17208-0014 are both strongly dominated by star formation, whereas Mrk 273 appears tobe powered by a mixture of star formation and an obscured AGN (e.g., Ptak et al. 2003; Farrah et al. 2003).”
• DETERMINING STAR FORMATION RATES FOR INFRARED GALAXIES (2008, methodology): “They apply to galaxies strongly dominated by star formation, as judged by X-ray properties, (e.g., Armus et al. 2007), broad SED characteristics (Farrah et al. 2003), and by their mid-infrared spectra (Genzel et al. 1998).”
• X-ray emission from star-forming galaxies – I. High-mass X-ray binaries (2011, methodology): “To this end, we used results of Farrah et al. (2003); Nardini et al. (2009); Yuan, Kewley, & Sanders (2010) who used various methods (IR and optical photometry, 5 − 8 µ Spitzer spectroscopy and SDSS data) to constrain the contribution of the AGN to the bolometric luminosity.”
• The Hubble Deep Field-North SCUBA Super-map - IV. Characterizing submillimetre galaxies using deep Spitzer imaging (2006, background): “However, it is notrepresentative of the entire sample of local ULIRGs, as its IR SED is cool compared to most IRAS-bright ULIRGs (Farrah et al. 2003), and has one of the most extreme mid- to far-IR slopes.”
• THE MOLECULAR GAS IN LUMINOUS INFRARED GALAXIES. II. EXTREME PHYSICAL CONDITIONS AND THEIR EFFECTS ON THE Xco FACTOR (2012, background): “It is also one of the very few ULIRGs where an AGN contributes more than half of the total IR luminosity (Farrah et al. 2003).”
• 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)).”
• High-Resolution Mid-Infrared Spectroscopy of Ultraluminous Infrared Galaxies (2007, background): “…due to nearby water ice and/or aliphatic hydrocarbon absorption, (2) destruction of PAHs in luminous starburst environments (Rigopoulou et al. 1999; Farrah et al. 2003; Beirão et al. 2006), (3) suppression of PAH EWs in compact starburst environments, and (4) increased general obscuration levels.”
• Early Growth and Efficient Accretion of Massive Black Holes at High Redshift (2003, background): “Additionally, the large emission-line widths (Figure 2) also indicate the black-hole masses are large.”
• The Herschel* PEP/HerMES luminosity function - I. Probing the evolution of PACS selected Galaxies to z ≃ 4 (2013, background): “– and dominates – the mid-IR (Farrah et al. 2003), reproducing the SEDs of “obscured” AGN regardless of their optical spectra (i.e. broad or narrow lines in the optical; Gruppioni et al. 2008).”
• Dusty Star Forming Galaxies at High Redshift (2014, background): “In fact, a number of works over the last decade have suggested using this two-component SED fitting technique (e.g. Dunne and Eales, 2001; Farrah et al., 2003; Galametz et al., 2012).”
• Revisiting the infrared spectra of active galactic nuclei with a new torus emission model (2005, methodology): “For the cold dust component, the major contributor to the emission at wavelengths longer than ∼ 50 µm, we chose to use starburst templates (see e.g. Farrah et al. 2003).”
• C-GOALS: Chandra observations of a complete sample of luminous infrared galaxies from the IRAS Revised Bright Galaxy Survey (2011, background): “Farrah et al. (2003) conclude that more than half of the bolometric luminosity originates from an AGN, based on an SED fit while optical data favour a starburst.”
• The Star Formation History of the Universe as Revealed by Deep Radio Observations (2008, methodology): “First, we assembled a local comparison sample of ULIRGs dominated by star formation (according to the studies of Farrah et al. 2003; Armus et al. 2007) and with radio measurements at least at 1.4 and 8.4 GHz (Condon et al. 1991).”