We report the discovery of an active galactic nucleus (AGN) pair in the interacting galaxy system IRAS 20210+1121 at z = 0.056. An XMM-Newton observation reveals the presence of an obscured (NH ∼ 5 × 1023 cm−2), Seyfert-like (L2–10 keV = 4.7 × 1042 erg s−1) nucleus in the northern galaxy, which lacks unambiguous optical AGN signatures. Our spectral analysis also provides strong evidence that the IR-luminous southern galaxy hosts a Type 2 quasar embedded in a bright starburst emission. In particular, the X-ray primary continuum from the nucleus appears totally depressed in the XMM-Newton band as expected in the case of a Compton-thick absorber, and only the emission produced by Compton scattering (“reflection”) of the continuum from circumnuclear matter is seen. As such, IRAS 20210+1121 seems to provide an excellent opportunity to witness a key, early phase in the quasar evolution predicted by the theoretical models of quasar activation by galaxy collisions.
Piconcelli E., Vignali C., Bianchi S., Mathur S., Fiore F., Guainazzi M., et al. (2010). Witnessing the key early phase of quasar evolution: an obscured AGN pair in the interacting galaxy IRAS 20210+1121. THE ASTROPHYSICAL JOURNAL LETTERS, 722, 147-151 [10.1088/2041-8205/722/2/L147].
Witnessing the key early phase of quasar evolution: an obscured AGN pair in the interacting galaxy IRAS 20210+1121
VIGNALI, CRISTIAN;LANZUISI, GIORGIO;
2010
Abstract
We report the discovery of an active galactic nucleus (AGN) pair in the interacting galaxy system IRAS 20210+1121 at z = 0.056. An XMM-Newton observation reveals the presence of an obscured (NH ∼ 5 × 1023 cm−2), Seyfert-like (L2–10 keV = 4.7 × 1042 erg s−1) nucleus in the northern galaxy, which lacks unambiguous optical AGN signatures. Our spectral analysis also provides strong evidence that the IR-luminous southern galaxy hosts a Type 2 quasar embedded in a bright starburst emission. In particular, the X-ray primary continuum from the nucleus appears totally depressed in the XMM-Newton band as expected in the case of a Compton-thick absorber, and only the emission produced by Compton scattering (“reflection”) of the continuum from circumnuclear matter is seen. As such, IRAS 20210+1121 seems to provide an excellent opportunity to witness a key, early phase in the quasar evolution predicted by the theoretical models of quasar activation by galaxy collisions.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
