We present a study of outflow (OF) and broad absorption line (BAL) systems in Mrk 231, and in similar infrared (IR) quasi‐stellar objects (QSOs). This study is based mainly on one‐dimensional and two‐dimensional spectroscopy (obtained at La Palma/William Herschel Telescope, Hubble Space Telescope, International Ultraviolet Explorer, European Southern Observatory/New Technology Telescope, Kitt Peak National Observatory, Apache Point Observatory and Complejo Astronomico El Leoncito observatories) plus Hubble Space Telescope images. For Mrk 231, we report evidence that the extreme nuclear OF process has at least three main components on different scales, which are probably associated with: (i) the radio jet, at parsec scale; (ii) the extreme starburst at parsec and kiloparsec scale. This OF has generated at least four concentric expanding superbubbles and the BAL systems.
Specifically, inside and very close to the nucleus the two‐dimensional spectra show the presence of an OF emission bump in the blend Hα+[N ii], with a peak at the same velocity of the main BAL‐I system (VEjection BAL‐I∼−4700 km s−1). This bump was more clearly detected in the area located at 0.6–1.5 arcsec (490–1220 pc), to the south‐west of the nucleus core, showing a strong and broad peak. In addition, in the same direction [at position angle (PA) ∼−120°, i.e. close to the PA of the small‐scale radio jet] at 1.7–2.5 arcsec, we also detected multiple narrow emission‐line components, with ‘greatly’ enhanced [N ii]/Hα ratio (very similar to the spectra of jets bow shocks). These results suggest that the BAL‐I system is generated in OF clouds associated with the parsec‐scale jet.
The Hubble Space Telescope images show four (or possibly five) nuclear superbubbles or shells with radii r∼ 2.9, 1.5, 1.0, 0.6 and 0.2 kpc. For these bubbles, the two‐dimensional Hα velocity field map and two‐dimensional spectra show the following. (i) At the border of the more extended bubble (S1), a clear expansion of the shell with blueshifted velocities (with circular shape and at a radius r∼ 5.0 arcsec). This bubble shows a rupture arc – to the south – suggesting that the bubble is in the blowout phase. The axis of this rupture or ejection (at PA ∼ 00°) is coincident with the axis of the intermediate and large‐scale structures detected at radio wavelengths. (ii) In addition, in the three more external bubbles (S1, S2, S3), the two‐dimensional William Herschel Telescope spectra show multiple emission‐line components with OF velocities, of 〈VOF Bubble〉 S1, S2 and S3 =[−(650 − 420) ± 30], [−500 ± 30] and [−230 ± 30] km s−1. (iii) In the whole circumnuclear region (1.8 < r < 5 arcsec), the [N ii]/Hα and [S ii]/Hα narrow emission‐line ratios show high values (>0.8), which are consistent with low‐ionization nuclear emission‐line region/OF processes associated with fast velocity shocks. Therefore, we suggest that these giant bubbles are associated with the large‐scale nuclear OF component, which is generated – at least in part – by the extreme nuclear starburst: giant...