An XMM-Newton hard X-ray survey of ultraluminous infrared galaxies

By A. Franceschini, V. Braito, M. Persic, R. Ceca, L. Bassani, M. Cappi, P. Malaguti, G. Palumbo, G. Risaliti, M. Salvati and 1 more. 2003

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XMM-Newton observations of 10 ultraluminous infrared galaxies (ULIRGs) from a 200-ks mini-survey programme are reported. The aim is to investigate in hard X-rays a complete ULIRG sample selected from the bright IRAS 60-μm catalogue. All sources are detected in X-rays, five of which for the first time. These observations confirm that ULIRGs are intrinsically faint X-ray sources, their observed X-ray luminosities being typically L 2 - 1 0 k e V ≤ 10 4 2 -10 4 3 erg s - 1 , whereas their bolometric (mostly infrared) luminosities are L b o l > 10 4 5 erg s - 1 . In all sources we find evidence for thermal emission from hot plasma with a rather constant temperature kT ≃ 0.7 keV, dominating the X-ray spectra below 1 keV, and probably associated with a nuclear or circumnuclear starburst. This thermal emission appears uncorrelated with the far-infrared luminosity, suggesting that, in addition to the ongoing rate of star formation, other parameters may also affect it. The soft X-ray emission appears to be extended on a scale of ∼30 kpc for Mrk 231 and IRAS 19254-7245, possible evidence of galactic superwinds. In these two sources, IRAS 20551-4250 and 23128-5919, we find evidence for the presence of hidden active galactic nuclei (AGNs), while a minor AGN contribution may be suspected also in IRAS 20100-4156. In particular, we have detected a strong (EW ∼ 2 keV) Fe K line at 6.4 keV in the spectrum of IRAS 19254-7245 and a weaker one in Mrk 231, suggestive of deeply buried AGNs. For the other sources, the X-ray luminosities and spectral shapes are consistent with hot thermal plasma and X-ray binary emissions of mainly starburst origin. We find that the 2-10 keV luminosities in these sources, most probably due to high-mass X-ray binaries, are correlated with L F I R : both luminosities are good indicators of the current global star formation rate in the Galaxy. The composite nature of ULIRGs is then confirmed, with hints for a predominance of the starburst over the AGN phenomenon in these objects even when observed in hard X-rays.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/baa1ce86d7cf260263c0c9ebd0520f429583903c

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Citations in the corpus

C-GOALS: Chandra observations of a complete sample of luminous infrared galaxies from the IRAS Revised Bright Galaxy Survey (2011, methodology): “Based on the XMM-Newton data, Franceschini et al. (2003) classified this galaxy as a starburst dominated source.”
A CHANDRA PERSPECTIVE ON GALAXY-WIDE X-RAY BINARY EMISSION AND ITS CORRELATION WITH STAR FORMATION RATE AND STELLAR MASS: NEW RESULTS FROM LUMINOUS INFRARED GALAXIES (2010, methodology): “Similar composite fits have been performed successfully for ULIRGs (see, e.g., Franceschini et al. 2003; Ptak et al. 2003).”
Infrared Power-Law Galaxies in the Chandra Deep Field-South: Active Galactic Nuclei and Ultraluminous Infrared Galaxies (2006, background): “Local universe ULIRGs are known to be intrinsically faint hard X-ray emitters, typically L2 10 keV ¼ 1041 1043 ergs s 1 (see Risaliti et al. 2000; Franceschini et al. 2003; Ptak et al. 2003; see also Fig.”
High-Resolution Mid-Infrared Spectroscopy of Ultraluminous Infrared Galaxies (2007, result): “…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 (Franceschini et al. 2003; Ptak et al. 2003), although some recent studies suggest a significantly greater average AGN contribution (Imanishi et…”
The subarcsecond mid-infrared view of local active galactic nuclei – II. The mid-infrared–X-ray correlation (2015, background): “On the other hand, Franceschini et al. (2003) and Brightman & Nandra (2011a) claim the detection of an obscured AGN in the shallower XMM-Newton data.”
The X-Ray Spectral Properties of SCUBA Galaxies (2005, background): “However, as argued in Persic et al. (2004; see also Franceschini et al. 2003), the X-ray emission from typical starburst galaxies will be dominated by long-lived LMXBs, which will be comparatively weak in intense star-forming galaxies.”
X-ray emission from star-forming galaxies – I. High-mass X-ray binaries (2011, methodology): “In two cases (IRAS 20551-4250 and IRAS 23128-5919) a good fit was obtained with a three-component model, according to Franceschini et al. (2003): a thermal component and a ”leaky -absorber” continuum, including an absorbed plus a non-absorbed power law spectrum of the same photon index.”
The Star Formation Rate and Dense Molecular Gas in Galaxies (2003, background): “Although AGNs are present in many ULIGs (e.g., Nagar et al. 2003; Franceschini et al. 2003), there is little evidence indicating that the AGN contribution is the dominant source of the FIR emission.”
THE MULTIPHASE STRUCTURE AND POWER SOURCES OF GALACTIC WINDS IN MAJOR MERGERS (2013, background): “…& Klöckner 2006), no [Ne V] or [O IV] emission is detected in the MIR (Farrah et al. 2007), the AGN fraction based on MIR diagnostics is only 0.11 (Veilleux et al. 2009), and the X-ray data do not show an obscured AGN (e.g., Franceschini et al. 2003; Teng & Veilleux 2010; Iwasawa et al. 2011b).”