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

Exposito, J.; Gratadour, Damien; Clénet, Y.; Rouan, D.

doi:10.1051/0004-6361/201116943

Cited by 12 publications

(17 citation statements)

References 56 publications

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“…While indirect evidence has been found in this object, thereby corroborating the unified model (Antonucci & Miller 1985;Raban et al 2009), many unknowns remain as to the nature and distribution of the obscuring material (Nenkova et al 2002). Recently, the complexity of the circumnuclear environment has been revealed by high angular resolution broad band observations in the near-IR (Rouan et al 2004;Gratadour et al 2006;Exposito et al 2011). In this Letter, we present the new elements introduced by polarimetry.…”

Section: Introductionmentioning

confidence: 67%

Polarimetric imaging of NGC 1068 at high angular resolution in the near infrared

Gratadour

Rouan

Grosset

et al. 2015

A&A

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Aims. One of the main observational challenges for investigating the central regions of active galactic nuclei (AGN) at short wavelengths, using high angular resolution, and high contrast observations, is to directly detect the circumnuclear optically thick material hiding the central core emission when viewed edge-on. The lack of direct evidence is limiting our understanding of AGN, and several scenarios have been proposed to cope for the diverse observed aspects of activity in a unified approach. Methods. Observations in the near-infrared spectral range have shown themselves to be powerful for providing essential hints to the characterisation of the unified model ingredients because of the reduced optical depth of the obscuring material. Moreover, it is possible to trace this material through light scattered from the central engine's closest environment, so that polarimetric observations are the ideal tool for distinguishing it from purely thermal and stellar emissions. Results. Here we show strong evidence that there is an extended nuclear torus at the center of NGC 1068 thanks to new adaptiveoptics-assisted polarimetric observations in the near-infrared. The orientation of the polarization vectors proves that there is a structured hourglass-shaped bicone and a compact elongated (20 × 60 pc) nuclear structure perpendicular to the bicone axis. The linearly polarized emission in the bicone is dominated by a centro-symmetric pattern, but the central compact region shows a clear deviation from the latter with linear polarization aligned perpendicular to the bicone axis.

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Section: Introductionmentioning

confidence: 67%

Polarimetric imaging of NGC 1068 at high angular resolution in the near infrared

Gratadour

Rouan

Grosset

et al. 2015

A&A

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“…6), though it is consistent with the error of ∼10% in the flux calibration, it could indicate that the stellar extinction is slightly overestimated -and consequently result in an underestimation of the temperature. Previous studies that used the same method in NIR spectra (e.g., Rodríguez-Ardila et al 2005b;Riffel et al 2009cRiffel et al , 2010 or broad-band SED modeling (e.g., Marco & Alloin 1998;Kishimoto et al 2007;Exposito et al 2011) found temperatures of 1000 K in Type-1 AGN and 800 K in Type-2s. From JHK spectroscopy, Landt et al (2011) also found temperatures ranging from 1100 to ∼1700 K for a sample of 23 Type-1 sources.…”

Section: Hot Dust Emissionmentioning

confidence: 99%

Is IRAS 01072+4954 a True-Seyfert 2?

Valencia-S.

Zuther

Eckart

et al. 2012

A&A

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In contrast to the predictions of the unified model, some X-ray unobscured Seyfert 2 galaxies have been discovered in the last decade. One of them, the starburst/Seyfert composite galaxy IRAS 01072+4954 (z = 0.0236), has a typical Type-1 X-ray emission, while its optical spectrum resembles an H ii galaxy and lacks the expected broad lines. We performed near-infrared integral-field observations of this object with the aim to determine the nature of its nuclear emission and to find indications for the existence or absence of a broad-line region. Several reasons have been proposed to explain this peculiar emission. We studied the validity of these hypotheses, including the possibility for this galaxy to be a True-Seyfert 2. We found little obscuration toward the nucleus A V = 2.5 mag, and a nuclear star-formation rate Σ SFR < 11.6 M yr −1 kpc −2 , which is below the average in Seyferts. Unresolved hot-dust emission with T ∼ 1150 K seems to indicate the presence of a torus with its axis close to the line of sight. We found that IRAS 01072+4954 hosts a low-mass black hole with an estimated mass of M BH ∼ 10 5 M . Its bolometric luminosity is L bol 2.5 × 10 42 erg s −1 , which yields a high accretion rate with an Eddington ratio λ Edd 0.2. If the relations found in more massive systems also apply to this case, then IRAS 01072+4954 should show broad emission lines with a FWHM broad ∼ (400−600) km s −1 . Indeed, some indications for such narrow broad-line components are seen in our data, but the evidence is not yet conclusive. This source therefore does not seem to be a True-Seyfert 2, but an extreme case of a narrow-line Seyfert 1, which, due to the faintness of the active nucleus, does not have strong Fe ii emission in the optical.

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“…This makes NGC 1068 an optimal target to investigate the morphology and kinematics of the different components in the AGN central regions: the infrared-emitting molecular gas, the X-ray obscuring torus, and the ionized gas (e.g., Exposito et al 2011;Krips et al 2011;Storchi-Bergmann et al 2012).…”

Section: Introductionmentioning

confidence: 99%

THECHANDRAHRC VIEW OF THE SUBARCSECOND STRUCTURES IN THE NUCLEAR REGION OF NGC 1068

Wang

Fabbiano

Karovska

et al. 2012

ApJ

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We have obtained a high spatial resolution X-ray image of the nucleus of NGC 1068 using the High Resolution Camera (HRC-I) on board the Chandra X-ray Observatory, which provides an unprecedented view of the innermost 1 arcsec radius region of this galaxy. The HRC image resolves the narrow-line region into X-ray emission clumps matching bright emission-line clouds in the HST [OIII] λ5007 images and allows comparison with subarcsecondscale radio jet for the first time. Two distinct X-ray knots are revealed at 1.3-1.4 arcsec northeast and southwest of the nucleus. Based on the combined X-ray, [O iii], and radio continuum morphology, we identify the locations of intense radio jet-cloud interaction. The [O iii] to soft X-ray ratios show that some of these clouds are strongly affected by shock heating, whereas in other locations the jet simply thrusts through with no signs of strong interaction. This is further strengthened by the presence of a kT ∼ 1 keV collisionally ionized component in the ACIS spectrum of a shock-heated cloud HST-G. We estimate that the kinematic luminosity of the jet-driven shocks is 6 × 10 38 erg s −1 , a negligible fraction (10 −4 ) of the estimated total jet power.

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

Cited by 12 publications

References 56 publications

Polarimetric imaging of NGC 1068 at high angular resolution in the near infrared

Polarimetric imaging of NGC 1068 at high angular resolution in the near infrared

Is IRAS 01072+4954 a True-Seyfert 2?

THECHANDRAHRC VIEW OF THE SUBARCSECOND STRUCTURES IN THE NUCLEAR REGION OF NGC 1068

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