Infrared 3-4 μm spectroscopy of nearby PG QSOs and AGN-nuclear starburst connections in high-luminosity AGN populations

Masatoshi Imanishi, Kohei Ichikawa, Tomoe Takeuchi, Nozomu Kawakatu, Nagisa Oi, Keisuke Imase

Research output: Contribution to journalArticlepeer-review

33 Citations (Scopus)


We present the results of infrared L-band (3-4 μm) slit spectroscopy of 30 PG QSOs at z < 0.17, a representative sample of local high-luminosity, optically selected AGNs. The 3.3 μm polycyclic aromatic hydrocarbon (PAH) emission feature is used to probe nuclear (< a few kpc) starburst activity and to investigate the connections between AGNs and nuclear starbursts in PG QSOs. The 3.3 μm PAH emission is detected in the individual spectra of 5/30 of the observed PG QSOs. We constructed a composite spectrum of PAH-undetected PG QSOs and discerned the presence of the 3.3 μm PAH emission therein. We estimated the nuclear-starburst and AGN luminosities from the observed 3.3 μm PAH emission and 3.35 μm continuum luminosities, respectively, and found that the nuclearstarburst-to-AGN luminosity ratios in PG QSOs are similar to those of previously studied AGN populations with lower luminosities, suggesting that AGN-nuclear starburst connections are valid over a wide luminosity range of AGNs in the local universe. The observed nuclear-starburst-to-AGN luminosity ratios in PG QSOs with available supermassive black-hole masses are comparable to a theoretical prediction based on the assumption that the growth of a supermassive black hole is controlled by starburst-induced turbulence.

Original languageEnglish
Pages (from-to)S447-S456
JournalPublications of the Astronomical Society of Japan
Issue numberSPEC. ISSUE 2
Publication statusPublished - 2011 Mar 25
Externally publishedYes


  • Galaxies: active
  • Galaxies: nuclei
  • Galaxies: starburst
  • Infrared: galaxies
  • Quasars: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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