Molecular hydrogen line emission in Seyfert galactic nuclei

Fischer, J. A.; Smith, H. A.; Geballe, T. R.; Simón, M.; Storey, J. W. V.

doi:10.1086/165584

Cited by 28 publications

(27 citation statements)

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“…This is also supported by the rovibrational lines observed in the near-IR (Fischer et al 1987;Krabbe et al 2000). For the Starburst galaxies it is harder to make any predictions: except perhaps from the case of the luminous IR galaxy NGC 6240 (Egami et al 2002, in preparation), no other starburst galaxy is a clear case candidate for shock excited H 2 emission.…”

Section: Shock Modelsmentioning

confidence: 58%

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An ISO–SWS survey of molecular hydrogen in starburst and Seyfert galaxies

Rigopoulou

Kunze

Lutz

et al. 2002

A&A

130

172

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Abstract. We present results from a survey of molecular hydrogen emission from a sample of Starburst and Seyfert galaxies carried out with the Infrared Space Observatory (ISO). Pure rotational H2 emission has been detected in a number of extragalactic objects and a variety of environments. A number of transitions from S(7) to S(0) are detected in both starbursts and Seyferts. Using excitation diagrams we derive temperatures and masses of the "warm" molecular hydrogen. We find that the temperature of the "warm" gas is similar in starbursts and Seyferts (those Seyferts for which we have firm detections of the S(0) line) with a value of around T ∼ 150 K. This "warm" gas accounts for as much as 10% of the total galactic mass (as probed by CO molecular observations) in starbursts. The fraction of "warm" gas is overall higher in Seyferts, ranging between 2-35%. We then investigate the origin of the warm H2 emission. Comparison with published theoretical models and Galactic templates implies that although emission from photodissociation regions (PDR) alone could explain the emission from starbursts and Seyferts, most likely a combination of PDR, shock emission and gas heated by X-rays (mostly for the Seyferts) is responsible for H2 excitation in extragalactic environments. Finally, we find that although PAH and H2 line emission correlate well in starbursts and the large scale emission in AGN, H2 emission is much stronger compared to PAH emission in cases where a "pure" AGN dominates the energy output.

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Section: Shock Modelsmentioning

confidence: 58%

“…Joseph et al 1984), Seyferts (e.g. Moorwood & Oliva 1988;Fischer et al 1987) and bright spirals (e.g. Puxley et al 1988).…”

Section: Introductionmentioning

confidence: 99%

An ISO–SWS survey of molecular hydrogen in starburst and Seyfert galaxies

Rigopoulou

Kunze

Lutz

et al. 2002

A&A

130

172

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“…Except in the early Universe, most H 2 is thought to be produced via surface reactions on interstellar grains (e.g., Gould and Salpeter, 1963;Hollenbach and Salpeter, 1971), since gas-phase reactions are predicted to be too slow. But due to our limited understanding of the relevant properties of interstellar grains (composition, structure and hydrogen coverage) and hence of grain surface reactions, the H 2 formation mechanism is not yet understood.…”

Section: Excitation and Formation Of Hmentioning

confidence: 99%

Molecular Hydrogen

et al. 2005

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Observations of H 2 line emission in galactic and extragalactic environments obtained with the Infrared Space Observatory (ISO) are reviewed. The diagnostic capability of H 2 observations is illustrated. We discuss what one has learned about such diverse astrophysical sources as photondominated regions, shocks, young stellar objects, planetary nebulae and starburst galaxies from ISO observations of H 2 emission. In this context, we emphasise use of measured H 2 line intensities to infer important physical quantities such as the gas temperature, gas density and radiation field and we discuss the different possible excitation mechanisms of H 2 . We also briefly consider future prospects for observation of H 2 from space and from the ground.

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“…The latter authors find a rotating ring-like CO structure with a ring radius of 3.5 ′′ . A hot (T = 1700 K) component of molecular hydrogen has also been directly detected through 2 µm emission within the central few arcseconds (Fischer et al 1987;Kawara & Taniguchi 1993;Inoue et al 1996). No attempt has yet been made to determine the physical properties of the molecular gas in this most unusual system.…”

Section: Introductionmentioning

confidence: 99%

Molecular gas in the Perseus cooling flow galaxy, NGC 1275

Bridges

Irwin

1998

Monthly Notices RAS

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The central arcminute of the Perseus cooling flow galaxy, NGC 1275, has been mapped with the JCMT in 12 CO(2-1) at 21 ′′ resolution, with detections out to at least 36 ′′ (12 kpc). Within the limits of the resolution and coverage, the distribution of gas appears to be roughly E-W, consistent with previous observations of CO, X-ray, Hα, and dust emission. The total detected molecular hydrogen mass is ∼ 1.6 × 10 10 M ⊙ , using a Galactic conversion factor. The inner central rotating disk is apparent in the data, but the overall distribution is not one of rotation. Rather, the line profiles are bluewards asymmetric, consistent with previous observations in HI and [OIII]. We suggest that the blueshift may be due to an acquired mean velocity of ∼ 150 km s −1 imparted by the radio jet in the advancing direction. Within the uncertainties of the analysis, the available radio energy appears to be sufficient, and the interpretation is consistent with that of Bohringer et al. (1993) for displaced X-ray emission.We have also made the first observations of 13 CO(2-1) and 12 CO(3-2) emission from the central 21 ′′ region of NGC 1275 and combined these data with IRAM data supplied by Reuter et al. (1993) to form line ratios over equivalent, well-sampled regions. An LVG radiative transfer analysis indicates that the line ratios are not well reproduced by a single value of kinetic temperature, molecular hydrogen density, and abundance per unit velocity gradient. At least two temperatures are suggested by a simple two-component LVG model, possibly reflecting a temperature gradient in this region.

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Molecular hydrogen line emission in Seyfert galactic nuclei

Cited by 28 publications

References 0 publications

An ISO–SWS survey of molecular hydrogen in starburst and Seyfert galaxies

An ISO–SWS survey of molecular hydrogen in starburst and Seyfert galaxies

Molecular Hydrogen

Molecular gas in the Perseus cooling flow galaxy, NGC 1275

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