The Mrk 231 molecular outflow as seen in OH

González-Alfonso, E.; Fischer, J.; Graciá-Carpio, J.; Falstad, Niklas; Sturm, E.; Meléndez, M.; Spoon, H. W. W.; Verma, Aprajita; Davies, R. I.; Lutz, D.; Aalto, S.; Polisensky, Emil; Poglitsch, A.; Veilleux, Sylvain; Contursi, A.

doi:10.1051/0004-6361/201321709

Cited by 81 publications

(107 citation statements)

References 59 publications

(94 reference statements)

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“…2.1.1. Compared to the fastest molecular outflows seen in Herschel studies of LIRGs (e.g., Fischer et al 2010;Sturm et al 2011;Veilleux et al 2013;González-Alfonso et al 2014b) the potential outflow velocities here are moderate, with the redshifted velocity component extending to ∼500 km s −1 .…”

Section: In-and Outflowing Gascontrasting

confidence: 61%

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Herschelspectroscopic observations of the compact obscured nucleus in Zw 049.057

Falstad

González-Alfonso

Aalto

et al. 2015

A&A

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Context. The luminous infrared galaxy Zw 049.057 contains a compact obscured nucleus where a considerable amount of the galaxy's luminosity is generated. This nucleus contains a dusty environment that is rich in molecular gas. One approach to probing this kind of environment and to revealing what is hidden behind the dust is to study the rotational lines of molecules that couple well with the infrared radiation emitted by the dust. Aims. We probe the physical conditions in the core of Zw 049.057 and establish the nature of its nuclear power source (starburst or active galactic nucleus). . We modeled the unresolved core of the galaxy using a spherically symmetric radiative transfer code. To account for the different excitation requirements of the various molecular transitions, we use multiple components and different physical conditions. Results. We present the full high-resolution SPIRE FTS spectrum of Zw 049.057, along with relevant spectral scans in the PACS range. We find that a minimum of two different components (nuclear and extended) are required in order to account for the rich molecular line spectrum of Zw 049.057. The nuclear component has a radius of 10−30 pc, a very high infrared surface brightness (∼10 14 L kpc −2 ), warm dust (T d > 100 K), and a very large H 2 column density (N H 2 = 10 24 −10 25 cm −2 ). The modeling also indicates high nuclear H 2 O (∼5 × 10 −6 ) and OH (∼4 × 10 −6 ) abundances relative to H 2 as well as a low 16 O/ 18 O-ratio of 50−100. We also find a prominent infall signature in the [O I] line. We tentatively detect a 500 km s −1 outflow in the H 2 O 3 13 → 2 02 line. Conclusions. The high surface brightness of the core indicates the presence of either a buried active galactic nucleus or a very dense nuclear starburst. The estimated column density towards the core of Zw 049.057 indicates that it is Compton-thick, making a buried X-ray source difficult to detect even in hard X-rays. We discuss the elevated H 2 O abundance in the nucleus in the context of warm grain and gas-phase chemistry. The H 2 O abundance is comparable to that of other compact (ultra-)luminous infrared galaxies such as NGC 4418 and Arp 220 -and also to hot cores in the Milky Way. The enhancement of 18 O is a possible indicator that the nucleus of Zw 049.057 is in a similar evolutionary stage as the nuclei of Arp 220 -and more advanced than NGC 4418. We discuss the origin of the extreme nuclear gas concentration and note that the infalling gas detected in [O I] implies that the gas reservoir in the central region of Zw 049.057 is being replenished. If confirmed, the H 2 O outflow suggests that the nucleus is in a stage of rapid evolution.

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Section: In-and Outflowing Gascontrasting

confidence: 61%

“…18 O is a so called secondary nuclide, produced by He burning (Maeder 1983) González-Alfonso et al 2014b) and hence has the most evolved starburst of the three. A caveat here is that it is assumed that all three galaxies have starbursts of a similar IMF with the same impact and ISM mixing.…”

Section: The 16 O/ 18 O Isotopic Ratiomentioning

confidence: 99%

Herschelspectroscopic observations of the compact obscured nucleus in Zw 049.057

Falstad

González-Alfonso

Aalto

et al. 2015

A&A

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“…For example, studies of Mrk 231 show that the ISM is being processed both by star-formation and supernovae (González-Alfonso et al 2014;Fischer et al 2010), while NGC 6240 shows clear evidence of shocks and mechanical heating . In NGC 1068, Hailey-Dunsheath et al (2012) find that the gas is either excited by X-rays or shocks, but cannot differentiate between the two.…”

Section: Casementioning

confidence: 99%

Radiative and mechanical feedback into the molecular gas of NGC 253

Rosenberg

Kazandjian

Werf

et al. 2014

A&A

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Starburst galaxies are galaxies or regions of galaxies undergoing intense periods of star formation. Understanding the heating and cooling mechanisms in these galaxies can give us insight to the driving mechanisms that fuel the starburst. Molecular emission lines play a crucial role in the cooling of the excited gas. With Herschel Spectral and Photometric Imaging Receiver we have been able to observe the rich molecular spectrum towards the central region of NGC 253. Carbon monoxide (CO, J = 4−3 to 13−12) is the brightest molecule in the Herschel wavelength range and together with ground-based low-J observations, the line fluxes trace the excitation of CO. By studying the CO excitation ladder and comparing the intensities to models, we investigate whether the gas is excited by UV radiation, X-rays, cosmic rays, or turbulent heating. Comparing the 12 CO and 13 CO observations to large velocity gradient models and photon-dominated region (PDR) models we find three main interstellar medium (ISM) phases. We estimate the density, temperature, and masses of these ISM phases. By adding 13 CO, HCN, and HNC line intensities, we are able to constrain these degeneracies and determine the heating sources. The first ISM phase responsible for the low-J CO lines is excited by PDRs, but the second and third phases, responsible for the mid to high-J CO transitions, require an additional heating source. We find three possible combinations of models that can reproduce our observed molecular emission. Although we cannot determine which of these is preferable, we can conclude that mechanical heating is necessary to reproduce the observed molecular emission and cosmic ray heating is a negligible heating source. We then estimate the mass of each ISM phase; 6 × 10 7 M for phase 1 (low-J CO lines), 3 × 10 7 M for phase 2 (mid-J CO lines), and 9 × 10 6 M for phase 3 (high-J CO lines) for a total system mass of 1 × 10 8 M .

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“…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). The high-velocity outflows discovered with Herschel were found to be ubiquitous and thus inferred to be wideangle in local ULIRGs (Veilleux et al 2013;Stone et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Molecular Outflows in Local ULIRGs: Energetics from Multitransition OH Analysis

González-Alfonso

Fischer

Spoon

et al. 2017

ApJ

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We report on the energetics of molecular outflows in 14 local Ultraluminous Infrared Galaxies (ULIRGs) that show unambiguous outflow signatures (P-Cygni profiles or high-velocity absorption wings) in the far-infrared lines of OH measured with the Herschel/PACS spectrometer. All sample galaxies are gas-rich mergers at various stages of the merging process. Detection of both ground-state (at 119 and 79 µm) and one or more radiatively-excited (at 65 and 84 µm) lines allows us to model the nuclear gas ( 300 pc) as well as the more extended components using spherically symmetric radiative transfer models. Reliable models and the corresponding energetics are found in 12 of the 14 sources. The highest molecular outflow velocities are found in buried sources, in which slower but massive expansion of the nuclear gas is also observed. With the exception of a few outliers, the outflows have momentum fluxes of (2 − 5) × L IR /c and mechanical luminosities of (0.1 − 0.3)% of L IR . The moderate momentum boosts in these sources ( 3) suggest that the outflows are mostly momentum-driven by the combined effects of AGN and nuclear starbursts, as a result of radiation pressure, winds, and supernovae remnants. In some sources (∼ 20%), however, powerful (10 10.5−11 L ⊙ ) AGN feedback and (partially) energy-conserving phases are required, with momentum boosts in the range 3 − 20. These outflows appear to be stochastic, strong-AGN feedback events that occur throughout the merging process. In a few sources, the outflow activity in the innermost regions has subsided in the last ∼ 1 Myr. While OH traces the molecular outflows at sub-kpc scales, comparison of the masses traced by OH with those previously inferred from tracers of more extended outflowing gas suggests that most mass is loaded (with loading factors ofṀ /SFR = 1 − 10) from the central galactic cores (a few × 100 pc), qualitatively consistent with an ongoing inside-out quenching of star formation. Outflow depletion timescales are < 10 8 yr, shorter than the gas consumption timescales by factors of 1.1 − 15, and are anti-correlated with the AGN luminosity.

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The Mrk 231 molecular outflow as seen in OH

Cited by 81 publications

References 59 publications

Herschelspectroscopic observations of the compact obscured nucleus in Zw 049.057

Herschelspectroscopic observations of the compact obscured nucleus in Zw 049.057

Radiative and mechanical feedback into the molecular gas of NGC 253

Molecular Outflows in Local ULIRGs: Energetics from Multitransition OH Analysis

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