ISO spectroscopy of star formation and active nuclei in the luminous infrared galaxy NGC 6240

Abstract

We present Infrared Space Observatory mid- and far-infrared spectroscopy of the merging galaxy NGC 6240, an object presenting many aspects of importance for the role of star formation and AGN activity in [ultra]luminous infrared galaxies. The mid-infrared spectrum shows starburst indicators in the form of low excitation fine-structure line emission and aromatic `PAH' features. A strong high excitation [OIV] line is observed which most likely originates in the Narrow Line Region of an optically obscured AGN. NGC 6240 shows extremely powerful emission in the pure rotational lines of molecular hydrogen. We argue that this emission is mainly due to shocks in its turbulent central gas component and its starburst superwind. The total shock cooling in infrared emission lines accounts for ~0.6% of the bolometric luminosity, mainly through rotational H_2 emission and the [OI] 63micron line. We analyse several ways of estimating the luminosities of the starburst and the AGN in NGC 6240 and suggest that the contributions to its bolometric luminosity are most likely in the range 50-75% starburst and 25-50% AGN.

arXiv comment5 figures. Accepted for publication in A&A

References in corpus (28)

• What Powers Ultra-luminous IRAS Galaxies?
• The Molecular Interstellar Medium in Ultraluminous Infrared Galaxies
• Discovery of a binary AGN in the ultraluminous infrared galaxy NGC 6240 using Chandra
• A 3 dimensional diagnostic diagram for Seyfert 2s: probing X-ray absorption and Compton thickness
• Far Infrared Spectroscopy of Normal Galaxies: Physical Conditions in the Interstellar Medium
• ASCA Observations of Seyfert 1 galaxies: III. The Evidence for Absorption & Emission due to Photoionized Gas
• A large mid-infrared spectroscopic and near-IR imaging survey of ULIRGs: their nature and evolution
• The nature and evolution of Ultraluminous Infrared Galaxies: A mid-infrared spectroscopic survey
• Ultra-Luminous Infrared Mergers: Elliptical Galaxies in Formation?
• Mid-Infrared line diagnostics of Active Galaxies -- A spectroscopic AGN survey with ISO-SWS
• Massive star formation and evolution in starburst galaxies: mid-infrared spectroscopy with ISO-SWS
• The [CII] 158 um Line Deficit in Ultraluminous Infrared Galaxies Revisited
• ISOCAM-CVF 5-12 mum Spectroscopy of Ultraluminous Infrared Galaxies
• Ultr-Luminous Infrared Galaxies: QSOs in Formation?
• Infrared to millimetre photometry of ultra-luminous IR galaxies: new evidence favouring a 3-stage dust model
• Multiwavelength Energy Distributions and Bolometric Luminosities of the 12--Micron Galaxy Sample
• Near-infrared Integral Field Spectroscopy and Mid-infrared Spectroscopy of the Starburst Galaxy M82
• Gas Dynamics in the Luminous Merger NGC 6240
• An ISO--SWS survey of molecular hydrogen in Starburst and Seyfert Galaxies
• A mid-infrared spectroscopic survey of starburst galaxies: excitation and abundances
• ISO LWS Spectroscopy of M82: A Unified Evolutionary Model
• The Ratio of Ortho- to Para-H2 in Photodissociation Regions
• Stellar Dynamics and the implications on the merger evolution in NGC6240
• Ice features in the mid-IR spectra of galactic nuclei
• ASCA spectroscopy of the luminous infrared galaxy NGC6240: X-ray emission from a starburst and a buried active nucleus
• ISOCAM view of the starburst galaxies M82, NGC253, and NGC1808
• Mid-infrared observations of NGC 1068 with ISOCAM
• RXTE observation of NGC 6240: a search for the obscured active nucleus

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• Spitzer Quasar and ULIRG Evolution Study (QUEST). IV. Comparison of 1-Jy Ultraluminous Infrared Galaxies with Palomar-Green Quasars
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• The Hubble Deep Field North SCUBA Super-map IV - Characterizing submillimetre galaxies using deep Spitzer imaging
• The relation between AGN hard X-ray emission and mid-infrared continuum from ISO spectra: Scatter and unification aspects
• Spitzer Quasar and ULIRG evolution study (QUEST): I. The origin of the far infrared continuum of QSOs
• Towards a Complete Census of AGNs in Nearby Galaxies: A Large Population of Optically Unidentified AGNs
• The subarcsecond mid-infrared view of local active galactic nuclei: I. The N- and Q-band imaging atlas
• Dust in starburst nuclei and ULIRGs: SED models for observers
• Jet-Powered Molecular Hydrogen Emission from Radio Galaxies
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• Spitzer Mid-Infrared Spectroscopy of Infrared Luminous Galaxies at z~2 II: Diagnostics
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• Detection of the Buried AGN in NGC 6240 with the Infrared Spectrograph on The Spitzer Space Telescope
• Aromatic Features in AGN: Star-Forming Infrared Luminosity Function of AGN Host Galaxies
• Mid-Infrared Atomic Fine-Structure Emission Line Spectra of Luminous Infrared Galaxies: Spitzer/IRS Spectra of the GOALS Sample
• SHINING, A Survey of Far Infrared Lines in Nearby Galaxies. II: Line-Deficit Models, AGN impact, [CII]-SFR Scaling Relations, and Mass-Metallicity Relation in (U)LIRGS
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• AGN are cooler than you think: the intrinsic far-IR emission from QSOs
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• A Spitzer Infrared Spectrograph Survey of Warm Molecular Hydrogen in Ultra-luminous Infrared Galaxies
• Far-infrared line spectra of active galaxies from the Herschel/PACS Spectrometer: the complete database
• Shocked Molecular Hydrogen in the 3C 326 Radio Galaxy System
• High Resolution Imaging of Warm and Dense Molecular Gas in the Nuclear Region of the Luminous Infrared Galaxy NGC6240
• Unveiling the nature of Ultraluminous Infrared Galaxies with 3-4 micron spectroscopy
• SHINING, A Survey of Far Infrared Lines in Nearby Galaxies. I: Survey Description, Observational Trends, and Line Diagnostics
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• Mid-infrared spectroscopy of infrared-luminous galaxies at z~0.5-3
• High-J CO SLEDs in nearby infrared bright galaxies observed by Herschel-PACS
• NGC6240: Merger-Induced Star Formation & Gas Dynamics
• Mid-infrared spectral evidence for a luminous dust enshrouded source in Arp220
• A panchromatic view of AGN
• The Spectral Energy Distributions and Infrared Luminosities of z \approx 2 Dust Obscured Galaxies from Herschel and Spitzer
• X-ray Spectral Constraints for z~2 Massive Galaxies: The Identification of Reflection-Dominated Active Galactic Nuclei
• The Core of NGC 6240 from Keck Adaptive Optics and HST NICMOS Observations
• Mid-Infrared Spectral Measures of Star-Formation and AGN Activity in Normal Galaxies
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• Host galaxy-active galactic nucleus alignments in the SDSS-DR7
• Lighting the dark molecular gas: H${}_2$ as a direct tracer
• A Large Mass of H2 in the Brightest Cluster Galaxy in Zwicky 3146
• The interstellar medium in high-redshift submillimeter galaxies as probed by infrared spectroscopy
• Dust Emission from Unobscured Active Galactic Nuclei
• The hard X-ray emission of the luminous infrared galaxy NGC 6240 as observed by NuSTAR
• Probing the Excitation of Extreme Starbursts: High Resolution Mid-IR Spectroscopy of Blue Compact Dwarfs
• The continuum and narrow line region of the NLS1 galaxy Mrk 766
• Shock excitation of H${}_2$ in the James Webb Space Telescope era
• Detection of Powerful Mid-IR H2 Emission in the Bridge between the Taffy Galaxies
• Star Formation and AGN activity in Galaxies classified using the 1.6 μm Bump and PAH features at $z=0.4-2$
• 3-5 micron spectroscopy of obscured AGNs in ULIRGs
• The Exceptional Soft X-ray Halo of the Galaxy Merger NGC 6240
• Obscured Activity: AGN, Quasars, Starbursts and ULIGs observed by the Infrared Space Observatory
• The AGNIFS survey: distribution and excitation of the hot molecular and ionised gas in the inner kpc of nearby AGN hosts
• XMM-Newton Spectroscopy of the Starburst Dominated Ultra Luminous Infrared Galaxy NGC 6240
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• Dense and Warm Molecular Gas between Double Nuclei of the Luminous Infrared Galaxy NGC 6240
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• Dissecting the spiral galaxy M83: mid-infrared emission and comparison with other tracers of star formation
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• MICONIC: Dual active galactic nuclei, star formation, and ionised gas outflows in NGC 6240 seen with MIRI/JWST
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• The Diagnostics and Possible Evolution in Active Galactic Nuclei Associated With Starburst Galaxies
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• Near- to Mid- Infrared Imaging and Spectroscopy of Two Buried AGNs of the Nearby Merging Galaxy NGC 6240 with Subaru/IRCS+AO and GTC/CanariCam
• Tracing the Ionization Structure of the Shocked Filaments of NGC 6240
• The JWST/NIRSpec view of the nuclear region in the prototypical merging galaxy NGC 6240
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