Infrared mergers and infrared quasi-stellar objects with galactic winds - III. Mrk 231: an exploding young quasi-stellar object with composite outflow/broad absorption lines (and multiple expanding superbubbles)

Abstract

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...

High resolution observations of HCN and HCO+J= 3–2 in the disk and outflow of Mrk 231

“…The feature is also brighter than the expected side-lobe response. Furthermore, Mrk 231 shows evidence of distinct optical circular shell like features at a whole range of radiiresulting from a complicated pattern of outflows and winds (Lípari et al 2005). Our HCN 3−2 ring-like feature coincides with their shell feature S3.…”

The Mrk 231 molecular outflow as seen in OH

“…It is possible that while radiation pressure affects the whole circumnuclear structure, winds are responsible for the highest velocity wings seen in OH. On the other hand, the high rate of mass loss derived here, together with the narrow-shell configuration favored for the HVC component, may suggest an intermittent (explosive) instead of a steady flow, consistent with the multiple, expanding, concentric supershells seen in the optical/UV at larger scales (Lípari et al 2005(Lípari et al , 2009). …”

Molecular Outflows in Local ULIRGs: Energetics from Multitransition OH Analysis

“…While feedback processes such as superwinds in ULIRGs and starbursts have been observed for decades in lines of ionized and neutral atomic gas (e.g., Heckman et al 1990;Veilleux et al 2005;Rupke et al 2002Rupke et al , 2005aLípari et al 2005Lípari et al , 2009Spoon & Holt 2009), outflows observed in lines that trace the molecular medium are also key to understanding and quantifying this process, because the molecular phase may carry a significant or even dominant fraction of the momentum and mass outflow rates in buried stages. Far-IR spectroscopy with Herschel Space Observatory Photoconductor Array Camera and Spectrometer (PACS) (Pilbratt et al 2010;Poglitsch et al 2010) has indeed revealed powerful molecular outflows in ULIRGs traced by OH, with velocities exceeding 1000 km s −1 in some sources and mass outflow rates of several hundreds M ⊙ yr −1 (Fischer et al 2010;Sturm et al 2011;Spoon et al 2013;Veilleux et al 2013;González-Alfonso et al 2014a, hereafter GA14).…”