Volume 559, November 2013
|Number of page(s)||10|
|Published online||13 November 2013|
Probing AGN triggering mechanisms through the starburstiness of the host galaxies
INAF – Osservatorio Astronomico di Roma, via di Frascati 33,
Monte Porzio Catone,
Accepted: 15 October 2013
We estimate the fraction of AGNs hosted in starburst galaxies (fbursty) as a function of the AGN luminosity predicted under the assumption that starburst events and AGN activity are triggered by galaxy interactions during their merging histories. The latter are described through Monte Carlo realizations, and are connected to star formation and BH accretion using a semi-analytic model of galaxy formation in a cosmological framework. The predicted fraction fbursty increases steeply with AGN luminosity from ≲0.2 at LX ≲ 1044 erg/s to ≳0.9 at LX ≳ 1045 erg/s over a wide redshift interval from z ≃ 0 to z ≃ 6. We compare the model predictions with new measurements of fbursty from a sample of X-ray selected AGNs in the XMM-COSMOS field at 0.3 < z < 2, and from a sample of QSOs (LX ≳ 1045 erg/s) in the redshift range 2 < z < 6.5. We find preliminary indications that under conservative assumptions half of the QSO hosts are starburst galaxies. This result provides motivation for future systematic studies of the stellar properties of high luminosity AGN hosts in order to constrain AGN triggering mechanisms.
Key words: galaxies: active / galaxies: evolution / galaxies: fundamental parameters / galaxies: interactions / galaxies: starburst
© ESO, 2013
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