The Ultraviolet Spectrum of the Liner NGC 4579

Barth, Aaron J.; Reichert, G. A.; Filippenko, A. V.; Ho, Luis C.; Shields, J. C.; Mushotzky, R. F.; Puchnarewicz, E. M.

doi:10.1086/118145

Cited by 51 publications

(96 citation statements)

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“…We have this object in our sample (see Table 1), with the FWHM of the MgII line of 6800 km s −1 . The mass estimate (10 6 M in our paper; 4 × 10 6 M suggested by Barth et al 1996) locates this object relatively far to the left in our diagrams (black filled triangle), but still within the allowed region for broad line objects. However, if the mass is actually much larger (Barth et al 2001 suggest a mass an order of magnitude higher based on black hole mass -bulge velocity dispersion relation) the object will move outside the allowed parameter space as defined by the ADAF model.…”

Section: Low Luminosity Agnsupporting

confidence: 62%

Constraints for the accretion disk evaporation rate in AGN from the existence of the Broad Line Region

Różáńska¹,

Kuraszkiewicz

2004

A&A

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Abstract.We analyze the consequences of the hypothesis that the formation of the Broad Line Region is intrinsically connected to the existence of the cold accretion disk. We assume that the Broad Line Region radius is reliably estimated by the formula of Kaspi et al. (2000, ApJ, 533, 631). We consider three models of the disappearance of the inner disk that limit the existence of the Broad Line Region: (i) the classical ADAF approach, i.e. the inner hot flow develops whenever it can exist; (ii) the disk evaporation model of Meyer & Meyer-Hofmeister (2002, A&A, 392, L5); (iii) the generalized disk evaporation model of Różańska & Czerny (2000b, A&A, 360, 1170. For each of the models, we determine the minimum value of the Eddington ratio and the maximum value of the broad line widths as functions of the viscosity parameter α and the magnetic field parameter β. We compare the predicted parameter space with observations of several AGN. Weak dependence of the maximum value of the FWHM and minimum value of the Eddington ratio on the black hole mass in our sample is noticeable. It seems to favor the description of the cold disk/hot inner flow transition as in the classical ADAF approach rather than with the model of disk evaporation due to conduction between the disk and accreting corona.

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Section: Low Luminosity Agnsupporting

confidence: 62%

Constraints for the accretion disk evaporation rate in AGN from the existence of the Broad Line Region

Różáńska¹,

Kuraszkiewicz

2004

A&A

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“…The AGN nature of NGC 4579 is confirmed by the detection of broad Hα and UV lines (Stauffer 1982;Filippenko & Sargent 1985;Barth et al 1996Barth et al , 2001Maoz et al 1998). It also has an unresolved nuclear hard X-ray (variable) source with a prominent broad Fe Kα line (Terashima et al 2000;Eracleous et al 2002;Dewangan et al 2004).…”

Section: The Liner/seyfert 19 Ngc 4579mentioning

confidence: 88%

Molecular gas in NUclei of GAlaxies (NUGA)

García‐Burillo

Fernández-García

Combes

et al. 2009

A&A

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In this paper we create a complete gravity torque map of the disk of the LINER/Seyfert 1.9 galaxy NGC 4579. We quantify the efficiency of angular momentum transport and search for signatures of secular evolution in the fueling process from r ∼ 15 kpc down to the inner r ∼ 50 pc around the active galactic nucleus (AGN). We use both the 1−0 and 2−1 line maps of 12 CO obtained with the Plateau de Bure Interferometer (PdBI) as part of the NUclei of Galaxies-(NUGA)-project. The CO(1−0) and CO(2−1) PdBI maps at 2.0 × 1.3 and 1.0 × 0.6 resolution, respectively, include the short spacing correction provided by IRAM-30 m data. We derive the stellar potential from an NIR (K band) wide field image of the galaxy. The K-band image, which reveals a large-scale stellar bar and a weak nuclear oval, together with a high-resolution Hi map of NGC 4579 obtained with the Very Large Array (VLA), allow us to extend the gravity torque analysis to the outer r ≥ 2 kpc disk. The bulk of the gas response traced by the new CO PdBI+30 m maps of NGC 4579 presented here follows the expected gas flow pattern induced by the bar potential in the presence of two inner Lindblad resonances (ILR) at r ∼ 500 pc and r ∼ 1.3 kpc. The morphology of the outer disk traced by Hi suggests that the neutral gas is currently piling up in a pseudo-ring formed by two winding spiral arms that are morphologically decoupled from the bar structure. The pseudo-ring is located inside the bar corotation (r CR ∼ 6 kpc) and close to the predicted position of the ultra harmonic resonance (UHR) (r UHR ∼ 3.8 kpc). The derived gravity torque budget in NGC 4579 shows that inward gas flow is occurring on different spatial scales in the disk. In the outer disk, the decoupling of the spiral allows the gas to efficiently populate the UHR region, and thus produce net gas inflow on intermediate scales. The corotation barrier seems to be overcome by secular evolution processes. The gas in the inner disk (r ≤ 2 kpc) is efficiently funneled by gravity torques down to r ∼ 300 pc. Closer to the AGN (r < 200 pc), gas feels negative torques due to the combined action of the large-scale bar and the inner oval. The two m = 2 modes act in concert to produce net gas inflow down to r ∼ 50 pc, providing clear smoking gun evidence of inward gas transport on short dynamical timescales (∼1−3 rotation periods).

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“…Röntgensatellit (ROSAT ) detected a compact nuclear X-ray source in NGC 4552 with a luminosity of L X $ 5 ; 10 40 ergs s À1 ( Brown & Bregman 1998;Beuing et al 1999;Schlegel et al 1998). Nuclear UV variability has also been detected in the LINER nucleus of the Sb galaxy NGC 4579 ( Barth et al 1996) and in the well-known AGN and jet of the gE galaxy M87 (Perlman et al 2003).…”

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confidence: 99%

UV/Optical Nuclear Activity in the gE Galaxy NGC 1399

O’Connell

Martin

Crane

et al. 2005

ApJ

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Using HST STIS, we have detected far-ultraviolet nuclear activity in the giant elliptical galaxy NGC 1399, the central and brightest galaxy in the Fornax I cluster. The source reached a maximum observed far-UV luminosity of $1:2 ; 10 39 ergs s À1 in 1999 January. It was detectable in earlier HST archival images in 1996 (B band ) but not in 1991 (V band ) or 1993 (UV ). It faded by a factor of $4 by mid-2000. The source is almost certainly associated with the low-luminosity AGN responsible for the radio emission in NGC 1399. The properties of the outburst are remarkably similar to the UV-bright nuclear transient discovered earlier in NGC 4552 by Renzini and coworkers. The source is much fainter than expected from its Bondi accretion rate (estimated from Chandra high-resolution X-ray images), even in the context of ''radiatively inefficient accretion flow'' models, and its variability also appears inconsistent with such models. High spatial resolution UV monitoring is a valuable means to study activity in nearby LLAGNs.

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The Ultraviolet Spectrum of the Liner NGC 4579

Cited by 51 publications

References 0 publications

Constraints for the accretion disk evaporation rate in AGN from the existence of the Broad Line Region

Constraints for the accretion disk evaporation rate in AGN from the existence of the Broad Line Region

Molecular gas in NUclei of GAlaxies (NUGA)

UV/Optical Nuclear Activity in the gE Galaxy NGC 1399

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