Outflowing OH${}^{+}$ in Markarian 231: the ionization rate of the molecular gas

Abstract

The oxygen-bearing molecular ions OH+, H2O+, and H3O+ are key species that probe the ionization rate of (partially) molecular gas that is ionized by X-rays and cosmic rays permeating the interstellar medium. We report Herschel far-infrared and submillimeter spectroscopic observations of OH+ in Mrk 231, showing both ground-state P-Cygni profiles, and excited line profiles with blueshifted absorption wings extending up to ~1000 km s^{-1}. In addition, OH+ probes an excited component peaking at central velocities, likely arising from the torus probed by the OH centimeter-wave megamaser. Four lines of H2O+ are also detected at systemic velocities, but H3O+ is undetected. Based on our earlier OH studies, we estimate an abundance ratio of OH/OH+~5-10 for the outflowing components and ~20 for the torus, and an OH+ abundance relative to H nuclei of ~>10^{-7}. We also find high OH+/H2O+ and OH+/H3O+ ratios, both are ~>4 in the torus and ~>10-20 in the outflowing gas components. Chemical models indicate that these high OH+ abundances relative to OH, H2O+, and H3O+ are characteristic of gas with a high ionization rate per unit density, ζ/n_H~(1-5)x10^{-17} cm^3 s^{-1} and ~(1-2)x10^{-16} cm^3 s^{-1} for the above components, respectively, and an ionization rate of ζ~(0.5-2)x10^{-12} s^{-1}. X-rays appear to be unable to explain the inferred ionization rate, and thus we suggest that low-energy (10-400 MeV) cosmic-rays are primarily responsible for the ionization with \dot{M}_{CR}~0.01 M_{sun} yr^{-1} and \dot{E}_{CR}~10^{44} erg s^{-1}, the latter corresponding to 1% of the AGN luminosity and similar to the energetics of the molecular outflow. We suggest that cosmic-rays accelerated in the forward shock associated with the molecular outflow are responsible for the ionization, as they diffuse through the outflowing molecular phase downstream.

arXiv comment25 pages, 11 figures

References in corpus (64)

• Herschel Space Observatory - An ESA facility for far-infrared and submillimetre astronomy
• The Photodetector Array Camera and Spectrometer (PACS) on the Herschel Space Observatory
• Massive Molecular Outflows and Evidence for AGN Feedback from CO Observations
• Quasar feedback revealed by giant molecular outflows
• Massive molecular outflows and negative feedback in ULIRGs observed by Herschel-PACS
• The physics of galactic winds driven by active galactic nuclei
• Fast Molecular Outflows in Luminous Galaxy Mergers: Evidence for Quasar Feedback from Herschel
• Wind from the black-hole accretion disk driving a molecular outflow in an active galaxy
• Cosmic-ray ionization of molecular clouds
• Quasar feedback and the origin of radio emission in radio-quiet quasars
• Clearing Out a Galaxy
• Discovery of an AGN-Driven Molecular Outflow in the Local Early-Type Galaxy NGC 1266
• Black hole accretion and star formation as drivers of gas excitation and chemistry in Mrk231
• The multi-phase winds of Markarian 231: from the hot, nuclear, ultra-fast wind to the galaxy-scale, molecular outflow
• Herschel PACS Spectroscopic Diagnostics of Local ULIRGs: Conditions and Kinematics in Mrk 231
• Observations of Arp 220 using Herschel-SPIRE: An Unprecedented View of the Molecular Gas in an Extreme Star Formation Environment
• Herschel Survey of Galactic OH+, H2O+, and H3O+: Probing the Molecular Hydrogen Fraction and Cosmic-Ray Ionization Rate
• Detection of HCN, HCO+ and HNC in the Mrk231 molecular outflow - Dense molecular gas in the AGN wind
• The Chemistry of Interstellar OH+, H2O+, and H3O+: Inferring the Cosmic Ray Ionization Rates from Observations of Molecular Ions
• The Herschel Comprehensive (U)LIRG Emission Survey (HerCULES): CO Ladders, fine structure lines, and neutral gas cooling
• Herschel/PACS spectroscopy of NGC 4418 and Arp 220: H2O, H2^{18}O, OH, ^{18}OH, O I, HCN and NH3
• The physics and the structure of the quasar-driven outflow in Mrk 231
• Herschel/HIFI observations of interstellar OH+ and H2O+ towards W49N: a probe of diffuse clouds with a small molecular fraction
• Diagnostics of AGN-driven Molecular Outflows in ULIRGs from Herschel-PACS Observations of OH at 119um
• Molecular outflows in local ULIRGs: energetics from multi-transition OH analysis
• Star Formation in Extreme Environments: The Effects of Cosmic Rays and Mechanical Heating
• Chemistry as a probe of the structures and evolution of massive star forming regions
• Galaxy-wide outflows: cold gas and star formation at high speeds
• The origin of fast molecular outflows in quasars: molecule formation in AGN-driven galactic winds
• Observational Signatures of Galactic Winds Powered by Active Galactic Nuclei
• Large--Scale Outflows in Galaxies
• X-ray chemistry in envelopes around young stellar objects
• Suppression of Star Formation in NGC 1266
• Extreme Cosmic-Ray-Dominated-Regions: a new paradigm for high star formation density events in the Universe
• High resolution observations of HCN and HCO+ J=3-2 in the disk and outflow of Mrk231 -Detection of vibrationally excited HCN in the warped nucleus
• Quasar Feedback in the Ultraluminous Infrared Galaxy F11119+3257: Connecting the Accretion Disk Wind with the Large-Scale Molecular Outflow
• Excited OH+, H2O+, and H3O+ in NGC 4418 and Arp 220
• The Implications of a High Cosmic-Ray Ionization Rate in Diffuse Interstellar Clouds
• P-Cygni Profiles of Molecular Lines toward Arp 220 Nuclei
• {\it NuSTAR} Reveals an Intrinsically X-ray Weak Broad Absorption Line Quasar in the Ultraluminous Infrared Galaxy Markarian 231
• High-resolution imaging of the molecular outflows in two mergers: IRAS17208-0014 and NGC1614
• Radiative cooling of swept up gas in AGN-driven galactic winds and its implications for molecular outflows
• Herschel observations of water vapour in Markarian 231
• Molecular gas heating mechanisms, and star formation feedback in merger/s tarbursts: NGC 6240 and Arp 193 as case studies
• Effects of magnetic fields on the cosmic-ray ionization of molecular cloud cores
• Chemistry in Cosmic-Ray Dominated Regions (CRDRs)
• Radio Continuum Evidence for Outflow and Absorption in the Seyfert 1 Galaxy Markarian 231
• Chemical Modelling of Young Stellar Objects, I. Method and Benchmarks
• High-J CO SLEDs in nearby infrared bright galaxies observed by Herschel-PACS
• Another piece of the puzzle: the fast HI outflow in Mrk231
• The Mrk 231 molecular outflow as seen in OH
• The Starburst in the Central Kiloparsec of Markarian 231
• Modeling the H2O submillimeter emission in extragalactic sources
• The Complete Ultraviolet Spectrum of the Archetypal "Wind-Dominated" Quasar Mrk~231: Absorption and Emission from a High-Speed Dusty Nuclear Outflow
• Spatially extended OH+ emission from the Orion Bar and Ridge
• High-excitation OH and H_2O lines in Markarian 231: the molecular signatures of compact far-infrared continuum sources
• Search for Molecular Outflows in Local Volume AGN with Herschel-PACS
• Chemical Analysis of a Diffuse Cloud along a Line of Sight Toward W51: Molecular Fraction and Cosmic-Ray Ionization Rate
• The Surprising Absence of Absorption in the Far-Ultraviolet Spectrum of Mrk 231
• Herschel spectroscopic observations of the compact obscured nucleus in Zw 049.057
• OH+ and H2O+ absorption toward PKS1830-211
• Evidence for a chemically differentiated outflow in Mrk 231
• The ionization rates of galactic nuclei and disks from Herschel/HIFI observations of water and its associated ions
• The Relativistic Jet-Accretion Flow-Wind Connection in Mrk\,231

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