The X-ray emission of local luminous infrared galaxies

M. Pereira-Santaella, A. Alonso-Herrero, M. Santos-Lleo, L. Colina, E. Jiménez-Bailón, A. L. Longinotti, G. H. Rieke, M. Ward, P. Esquej

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77 Scopus citations


We study the X-ray emission of a representative sample of 27 local luminous infrared galaxies (LIRGs). The median IR luminosity of our sample is log L IR/L = 11.2, therefore the low-luminosity end of the LIRG class is well represented. We used new XMM-Newton data as well as Chandra and XMM-Newton archive data. The soft X-ray (0.5-2? keV) emission of most of the galaxies (>80%), including LIRGs hosting a Seyfert 2 nucleus, is dominated by star-formation-related processes. These LIRGs follow the star-formation rate (SFR) versus soft X-ray luminosity correlation observed in local starbursts. We find that ∼15% of the non-Seyfert LIRGs (3 out of 20) have an excessively hard X-ray emission relative to that expected from star-formation, which might indicate the presence of an obscured AGN. The rest of the non-Seyfert LIRGs follow the SFR versus hard X-ray (2-10? keV) luminosity correlation of local starbursts. The non-detection of the 6.4? keV Fe? Kα emission line in the non-Seyfert LIRGs allows us to put an upper limit on the bolometric luminosity of an obscured AGN, Lbol <1043? erg? s-1. That is, if these galaxies were hosting a low-luminosity AGN, its contribution to the total luminosity would be less than 10%. Finally we estimate that the AGN contribution to the total luminosity for our sample of local LIRGs is between 7% and 10%.

Original languageEnglish (US)
Article numberA93
JournalAstronomy and astrophysics
StatePublished - 2011


  • X-ray: galaxies
  • galaxies: active
  • galaxies: starburst

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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