J. A. de Jong

Publications (3)5.53 Total impact

• Source

  Available from: ArXiv

  Article: Herschel-PACS Observations of Far-IR CO Line Emission in NGC 1068: Highly Excited Molecular Gas in the Circumnuclear Disk

  S. Hailey-Dunsheath, E. Sturm, J. Fischer, A. Sternberg, J. Graciá-Carpio, R. Davies, E. González-Alfonso, D. Mark, A. Poglitsch, A. Contursi, R. Genzel, D. Lutz, L. Tacconi, S. Veilleux, A. Verma, J. A. de Jong
  [show abstract] [hide abstract]
  ABSTRACT: We report the detection of far-IR CO rotational emission from the prototypical Seyfert 2 galaxy NGC 1068. Using Herschel-PACS, we have detected 11 transitions in the J_upper=14-30 (E_upper/k_B = 580-2565 K) range, all of which are consistent with arising from within the central 10" (700 pc). The detected transitions are modeled as arising from 2 different components: a moderate excitation (ME) component close to the galaxy systemic velocity, and a high excitation (HE) component that is blueshifted by ~80 km s^{-1}. We employ a large velocity gradient (LVG) model and derive n_H2~10^{5.6} cm^{-3}, T_kin~170 K, and M_H2~10^{6.7} M_sun for the ME component, and n_H2~10^{6.4} cm^{-3}, T_kin~570 K, and M_H2~10^{5.6} M_sun for the HE component, although for both components the uncertainties in the density and mass are plus/minus (0.6-0.9) dex. We compare the CO line profiles with those of other molecular tracers observed at higher spatial and spectral resolution, and find that the ME transitions are consistent with these lines arising in the ~200 pc diameter ring of material traced by H_2 1-0 S(1) observations. The blueshift of the HE lines may also be consistent with the bluest regions of this H_2 ring, but a better kinematic match is found with a clump of infalling gas ~40 pc north of the AGN. We discuss the prospects of placing the HE component near the AGN, and conclude that while the moderate thermal pressure precludes an association with the ~1 pc radius H_2O maser disk, the HE component could potentially be located only a few parsecs more distant from the AGN, and might then provide the N_H~10^{25} cm^{-2} column obscuring the nuclear hard X-rays. Finally, we also report sensitive upper limits extending up to J_upper=50, which place constraints on a previous model prediction for the CO emission from the X-ray obscuring torus. [Abridged]
  02/2012;
• Article: Far-infrared Line Deficits in Galaxies with Extreme Ratios

  J. Graciá-Carpio, E. Sturm, S. Hailey-Dunsheath, J. Fischer, A. Contursi, A. Poglitsch, R. Genzel, E. González-Alfonso, A. Sternberg, A. Verma, N. Christopher, R. Davies, H. Feuchtgruber, J. A. de Jong, D. Lutz, and L. J. Tacconi
  [show abstract] [hide abstract]
  ABSTRACT: We report initial results from the far-infrared fine structure line observations of a sample of 44 local starbursts, Seyfert galaxies, and infrared luminous galaxies obtained with the PACS spectrometer on board Herschel. We show that the ratio between the far-infrared luminosity and the molecular gas mass, , is a much better proxy for the relative brightness of the far-infrared lines than LFIR alone. Galaxies with high ratios tend to have weaker fine structure lines relative to their far-infrared continuum than galaxies with . A deficit of the [C II] 158 μm line relative to L FIR was previously found with the Infrared Space Observatory, but now we show for the first time that this is a general aspect of all far-infrared fine structure lines, regardless of their origin in the ionized or neutral phase of the interstellar medium. The value where these line deficits start to manifest is similar to the limit that separates between the two modes of star formation recently found in galaxies on the basis of studies of their gas-star formation relations. Our finding that the properties of the interstellar medium are also significantly different in these regimes provides independent support for the different star-forming relations in normal disk galaxies and major merger systems. We use the spectral synthesis code Cloudy to model the emission of the lines. The expected increase of the ionization parameter with can simultaneously explain the line deficits in the [C II], [N II], and [O I] lines.
  The Astrophysical Journal Letters 01/2011; 728(1):L7. · 5.53 Impact Factor
• Source

  Available from: ArXiv

  Article: Far-Infrared Line Deficits in Galaxies with Extreme Lfir/MH2 Ratios

  J. Graciá-Carpio, E. Sturm, S. Hailey-Dunsheath, J Fischer, A. Contursi, A. Poglitsch, R. Genzel, E. González-Alfonso, A. Sternberg, A Verma, N. Christopher, R Davies, H. Feuchtgruber, J. A. de Jong, D. Lutz, L. J. Tacconi
  [show abstract] [hide abstract]
  ABSTRACT: We report initial results from the far-infrared fine structure line observations of a sample of 44 local starbursts, Seyfert galaxies and infrared luminous galaxies obtained with the PACS spectrometer on board Herschel. We show that the ratio between the far-infrared luminosity and the molecular gas mass, Lfir/MH2, is a much better proxy for the relative brightness of the far-infrared lines than Lfir alone. Galaxies with high Lfir/MH2 ratios tend to have weaker fine structure lines relative to their far-infrared continuum than galaxies with Lfir/MH2 < 80 Lsun/Msun. A deficit of the [C II] 158 micron line relative to Lfir was previously found with the ISO satellite, but now we show for the first time that this is a general aspect of all far-infrared fine structure lines, regardless of their origin in the ionized or neutral phase of the interstellar medium. The Lfir/MH2 value where these line deficits start to manifest is similar to the limit that separates between the two modes of star formation recently found in galaxies on the basis of studies of their gas-star formation relations. Our finding that the properties of the interstellar medium are also significantly different in these regimes provides independent support for the different star forming relations in normal disk galaxies and major merger systems. We use the spectral synthesis code Cloudy to model the emission of the lines. The expected increase of the ionization parameter with Lfir/MH2 can simultaneously explain the line deficits in the [C II], [N II] and [O I] lines.
  01/2011;