Dissipative Heating and Quasar Emission Lines

Bottorff, M. C.; Ferland, Gary J.

doi:10.1086/339058

Cited by 17 publications

(15 citation statements)

References 69 publications

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“…Done & Krolik 1996;Elvis 2000;Ferland et al 2009;Gaskell 2009;Shapovalova et al 2010). Second, there has been considerable discussion of the heating efficiency of the LIL BLR: radiative heating seems too low compared with the observed radiation field, and additional mechanical heating seems to be required (Collin-Souffrin et al 1988;Bottorff & Ferland 2002;Shapovalova et al 2004;Shapovalova et al 2010).…”

Section: Discussionmentioning

confidence: 99%

The origin of the broad line region in active galactic nuclei

Czerny

Hryniewicz

2010

A&A

251

213

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Aims. Although broad emission lines are the most reliable signature of the nuclear activity of a galaxy and the location of the emitting material is well measured by the reverberation method, the physical cause of the formation of the broad line region remains unclear. We attempt to place some constraints on its origin. Methods. We study the properties of the accretion disk underlying the broad line region. Results. We find that the effective temperature at the disk radius corresponding to the location of the broad line region, as inferred from the Hβ line, is universal in all monitored sources and equal to 1000 K. This value is close to the limiting value that permits the existence of the dust. Conclusions. The likely origin of the low ionization part of the broad line region is the strong local dusty wind from the disk. This wind becomes exposed to the irradiation by the central regions when moving higher above the disk surface and subsequently behaves like a failed wind, thus leading to a local mixture of inflow and outflow. This may provide the physical explanation of the turbulence needed both to smooth the line profiles as well as provide additional mechanical heating.

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Section: Discussionmentioning

confidence: 99%

The origin of the broad line region in active galactic nuclei

Czerny

Hryniewicz

2010

A&A

251

213

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“…Although suggestive of a high abundance, since nitrogen is a secondary element, this is not a particularly likely explanation. Conceivably, there is an additional physical mechanism involved such as the gas micro turbulence with associated dissipative heating as suggested in Kraemer et al (2007); see also Bottorff & Ferland 2002).…”

Section: Photoionization Modelingmentioning

confidence: 97%

A Spectroscopic Search for AGN Activity in the Reionization Era

Laporte

Nakajima

Ellis

et al. 2017

ApJ

136

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The ubiquity of Lyman alpha (Lyα) emission in a sample of four bright [O III]-strong star-forming galaxies with redshifts above seven has led to the suggestion that such luminous sources represent a distinct population compared with their fainter, more numerous counterparts. The presence of Lyα emission within the reionization era could indicate that these sources created early ionized bubbles due to their unusually strong radiation, possibly because of the presence of active galactic nuclei. To test this hypothesis, we secured long integration spectra with XSHOOTER on the VLT for three z 7  sources selected to have similar luminosities and prominent excess fluxes in the IRAC 3.6 or 4.5 μm band, usually attributed to strong [O III] emission. We secured additional spectroscopy for one of these galaxies at z=7.15 using MOSFIRE at the Keck telescope. For the most well-studied source in our sample with the strongest IRAC excess, we detect significant nebular emission from He II and N V indicative of a non-thermal source. For the other two sources at z= 6.81 and z=6.85, for which no previous optical/nearinfrared spectroscopy was available, Lyα is seen in one and C III] emission in the other. Although based on a modest sample, our results further support the hypothesis that the phenomenon of intense [O III] emission is associated preferentially with sources lying in early ionized bubbles. However, even though one of our sources at z=7.15 suggests the presence of non-thermal radiation, such ionized bubbles may not uniquely arise in this manner. We discuss the unique advantages of extending such challenging diagnostic studies with JWST.

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“…Using photoionization models, they were able to generate smooth line profiles from a small number of clouds. Bottorff & Ferland (2002 expanded on this by examining the effects of dissipative turbulence. In the case of non-dissipative turbulence, the turbulent motions persist, whereas, in the dissipative case, the motion is converted into heat.…”

Section: Introductionmentioning

confidence: 99%

On the Effects of Dissipative Turbulence on the Narrow Emission‐Line Ratios in Seyfert Galaxies

Kraemer

Bottorff

Crenshaw

2007

ApJ

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We present a photoionization model study of the effects of micro-turbulence and dissipative heating on emission lines for number and column densities, elemental abundances, and ionizations typical for the narrow emission line regions (NLRs) of Seyfert galaxies. Earlier studies of NLR spectra generally found good agreement between the observations and the model predictions for most strong emission lines, such as, and the H and He recombination lines. Nevertheless, the strengths of lines from species with ionization potentials greater than that of He + (54.4 eV), e.g. N +4 and Ne +4 , were often under-predicted. Among the explanations suggested for these discrepancies were (selectively) enhanced elemental abundances and contributions from shock heated gas. Interestingly, the NLR lines have widths of several 100 km s −1 , well in excess of the thermal broadening. If this is due to micro-turbulence, and the turbulence dissipates within the emission-line gas, the gas can be heated in excess of that due to photoionization. We show that the combined effects of turbulence and dissipative heating can strongly enhance N V λ1240 (relative to He II λ1640), while the heating alone can boost the strength of [Ne V] λ3426. We suggest that this effect is present in the NLR, particularly within ∼ 100 pc of the central engine. Finally, since micro-turbulence would make clouds robust against instabilities generated during acceleration, it is not likely to be a coincidence that the radially outflowing emission-line gas is turbulent.

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Dissipative Heating and Quasar Emission Lines

Cited by 17 publications

References 69 publications

The origin of the broad line region in active galactic nuclei

The origin of the broad line region in active galactic nuclei

A Spectroscopic Search for AGN Activity in the Reionization Era

On the Effects of Dissipative Turbulence on the Narrow Emission‐Line Ratios in Seyfert Galaxies

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