Extreme galactic wind and Wolf-Rayet features in infrared mergers and infrared quasi-stellar objects

Abstract

We report, as a part of a long-term study of infrared (IR) mergers and IR quasi-stellar objects (QSOs), detailed spectroscopic evidence for outflow (OF) and Wolf–Rayet (WR) features in the nearby mergers NGC4038/39 and IRAS 23128−5919 (with low-velocity OF); and the nearby QSOs IRAS 01003−2238 and 13218+0552 (with extreme velocity OF, EVOF). We also study the presence of EVOF in a complete sample of ultraluminous IR galaxies and QSOs (‘The IRAS 1-Jy Survey’, 118 objects).We found EVOF in IRAS 11119+3257, 14394+5332, 15130−1958 and 15462−0450. The low-velocity OF components were detected mainly in objects with starburst processes, i.e. OF associated with galactic winds generated in multiple type II supernova (SN) explosions and massive stars. Meanwhile the EVOF were detected mainly in objects with strong starburst plus obscured IR QSOs; which suggests that the coexistence of both processes could generate EVOF. Hubble Space Telescope (HST) images of IR+BAL+Fe II QSOs show in practically all of these objects ‘arc or shell’ features probably associated with galactic winds [i.e. with multiple type II SN explosions or with starburst+active galactic nuclei (AGN)] or merger processes. In addition, we analyse the presence of Wolf–Rayet features in part of the large sample of bright PG-QSOs. We found possible WR features in the Fe II PG-QSOs PG 1244+026, 1444+407, 1448+273 and 1535+547. The results are discussed mainly within the framework of the composite scenario: starburst+AGN. We analyse the presence of extreme starburst and galactic winds as a possible link between IR mergers and IR QSOs. Finally, we discuss the probable role of mergers, extreme starburst and galactic winds processes in BAL-QSOs and galaxies in formation.