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首页> 美国政府科技报告 >Herschel-PACS Observations of Far-IR CO Line Emission in NGC 1068: Highly Excited Molecular Gas in the Circumnuclear Disk.
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Herschel-PACS Observations of Far-IR CO Line Emission in NGC 1068: Highly Excited Molecular Gas in the Circumnuclear Disk.

机译：Herschel-paCs对NGC 1068中远红外CO线发射的观察：环核盘中高度激发的分子气体。

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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)/kappa(B) = 580-2565 Kappa) range, all of which are consistent with arising from within the central 10' (700 pc). The detected transitions are modeled as arising from two different components: a moderate-excitation (ME) component close to the galaxy systemic velocity and a high-excitation (HE) component that is blueshifted by approx. 80 km s(-1). We employ a large velocity gradient model and derive Eta(H2) approx. 10(5.6) cm(-3), T(kin) approx. 170 K, and M(H2) approx. 10(6.7) M for the ME component and eta(H2) approx. 10(6.4) cm(-3), T(kin) approx. 570 K, and M(H2) approx. 10(5.6) M for the HE component, although for both components the uncertainties in the density and mass are plus or minus (0.6-0.9) dex. Both components arise from denser and possibly warmer gas than traced by low-J CO transitions, and the ME component likely makes a significant contribution to the mass budget in the nuclear region. 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 approx. 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 approx. 40 pc north of the active galactic nucleus (AGN). We consider potential heating mechanisms and conclude that X-ray or shock heating of both components is viable, while far-UV heating is unlikely.

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