Resolved Spectroscopy of the Narrow‐Line Region in NGC 1068. III. Physical Conditions in the Emission‐Line Gas

Kraemer, S. B.; Crenshaw, D. Michael

doi:10.1086/317246

Cited by 81 publications

(79 citation statements)

References 53 publications

(83 reference statements)

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“…We assumed typical conditions for the [O III] emitting region in the NLR, e.g. a hydrogen number density of 10 4 cm −3 (see Kraemer et al 2000b;Kraemer & Crenshaw 2000), a column density of 10 21 cm −2 (which ensured that the models were radiation bounded), and solar abundances (e.g. Grevesse & Anders 1989).…”

Section: Luminosity Comparisonmentioning

confidence: 99%

On the Relationship between the Optical Emission‐Line and X‐Ray Luminosities in Seyfert 1 Galaxies

Kraemer

George

Crenshaw

et al. 2004

ApJ

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We have explored the relationship between the [O III] λ5007 and the 2-10 keV luminosities for a sample of Broad-and Narrow-Line Seyfert 1 galaxies (BLSy1 and NLSy1, respectively). We find that both types of Seyferts span the same range in luminosity and possess similar [O III]/X-ray ratios. The NLSy1s are more luminous than BLSy1s, when normalized to their central black hole masses, which is attributed to higher mass accretion rates. However, we find no evidence for elevated [O III]/X-ray ratios in NLSy1s, which would have been expected if they had excess EUV continuum emission compared to BLSy1s. Also, other studies suggest that the gas in narrow-line regions (NLR) of NLSy1s and NLSy1s span a similar range in ionization, contrary to what is expected if those of the former are exposed to a stronger flux of EUV radiation. The simplest interpretation is that, like BLSy1s, a large EUV bump is not present in NLSy1s. However, we show that the [OIII]/X-ray ratio can be lowered as a result of absorption of the ionizing continuum by gas close to the central source, although there is no evidence that intrinsic line-of-sight absorption is more common among NLSy1s, as would be expected if there were a larger amount of circumnuclear gas. Other possible explanations include: 1) anisotropic emission of the ionizing radiation, 2) higher gas densities in the NLR of NLSy1s, resulting in lower average

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Section: Luminosity Comparisonmentioning

confidence: 99%

On the Relationship between the Optical Emission‐Line and X‐Ray Luminosities in Seyfert 1 Galaxies

Kraemer

George

Crenshaw

et al. 2004

ApJ

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“…At a lower spatial resolution than NaCo, both mechanisms have been proposed. Kraemer & Crenshaw (2000b) found that the central source is able to produce coronal lines. However, they also found evidence for an additional ionizing source, which could be the UV-X radiation generated by fast shocks (∼1000 km s −1 ).…”

Section: Introductionmentioning

confidence: 99%

Star formation and jet-induced coronal lines near the core of NGC 1068

Exposito

Gratadour

Clénet

et al. 2011

A&A

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Context. Active galactic nuclei (AGNs) are very luminous galaxies from the ultraviolet (UV) to the far infrared (FIR). To study regions near the core, which are dominated by dust, IR is the perfect spectral range because of the lower optical depth of the dust. However, these galaxies are usually distant, and the structures near the core are faint compared to the central source. High resolution and high contrast are mandatory to study the inner structures of AGNs and better understand the interaction between the central core and its surroundings. Aims. Our goal is to propose an explanation for the coronal lines in our spectra of NGC 1068 at a far distance (few tens of parsec) from the central source inside wave-like structures that we call nodules. Methods. NGC 1068 was observed with NaCo at ESO/VLT, using long-slit spectroscopy at 2.2 μm and 3.5 μm. Reduced spectra were compared to the output of Cloudy, using various ionizing continua: the continuum of the central source, young stars, and radiative shocks caused by the jet. Results. For the first time, thanks to the resolution provided by NaCo, near-IR coronal emission can be precisely associated to structures observable in the IR broad-band images. We found that coronal lines observed in the nodules cannot be caused by photoionization by the central source but are instead caused by a local jet-induced ionizing continuum. In addition, studying the Brackett-γ line (Brγ) and CO 2-0 band head, we deduced a star density within the four nodules (∼800 000 stars) compatible with super star cluster (hereafter SSC) models.

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“…determined that emission lines from the ILR of NGC 4151 could arise in the same gas responsible for the UV and soft X-ray absorption. In photoionization modeling studies of the NLR in NGC 4151 (Kraemer et al 2000), NGC 1068 (Kraemer & Crenshaw 2000a, 2000b, Mrk 3 ), and Mrk 573 ), in order to account for the strength emission lines such as [Ne v] λ3426 and [Fe v] λ6087, we argued for the presence of relatively highly ionized, e.g., logU ∼ −1, matter-bounded gas within 50 pc of the AGN. Although the column densities of these components are typically several times greater than what we have determined for components 2, 5, and 7 in NGC 4051, they span the same range in U.…”

Section: Radial Distances and Density Constraintsmentioning

confidence: 99%

Observations of Outflowing Ultraviolet Absorbers in NGC 4051 With the Cosmic Origins Spectrograph

Kraemer¹,

Crenshaw²,

Dunn³

et al. 2012

ApJ

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We present new Hubble Space Telescope (HST)/Cosmic Origins Spectrograph (COS) observations of the narrowline Seyfert 1 galaxy NGC 4051. These data were obtained as part of a coordinated observing program including X-ray observations with the Chandra/High Energy Transmission Grating (HETG) spectrometer and Suzaku. We detected nine kinematic components of UV absorption, which were previously identified using the HST/Space Telescope Imaging Spectrograph (STIS). None of the absorption components showed evidence for changes in column density or profile within the ∼10 yr between the STIS and COS observations, which we interpret as evidence of (1) saturation, for the stronger components, or (2) very low densities, i.e., n H < 1 cm −3 , for the weaker components. After applying a + 200 km s −1 offset to the HETG spectrum, we found that the radial velocities of the UV absorbers lay within the O vii profile. Based on photoionization models, we suggest that, while UV components 2, 5, and 7 produce significant O vii absorption, the bulk of the X-ray absorption detected in the HETG analysis occurs in more highly ionized gas. Moreover, the mass-loss rate is dominated by high-ionization gas which lacks a significant UV footprint.

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Resolved Spectroscopy of the Narrow‐Line Region in NGC 1068. III. Physical Conditions in the Emission‐Line Gas

Cited by 81 publications

References 53 publications

On the Relationship between the Optical Emission‐Line and X‐Ray Luminosities in Seyfert 1 Galaxies

On the Relationship between the Optical Emission‐Line and X‐Ray Luminosities in Seyfert 1 Galaxies

Star formation and jet-induced coronal lines near the core of NGC 1068

Observations of Outflowing Ultraviolet Absorbers in NGC 4051 With the Cosmic Origins Spectrograph

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