Platform Diving:

Nardini, Bob

doi:10.2307/j.ctt1wf4ds0.9

Cited by 8 publications

(11 citation statements)

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“…As an archetypal barred galaxy, it has been extensively observed (e.g., Lindblad 1999). While the Seyfert 1.8 nucleus is obvious in optical and X-rays (Nardini et al 2015), it is hardly seen in radio. Stevens et al (1999) discuss a marginal radio jet, the center of which corresponds to the central X-ray position.…”

Section: Molecular Gas Distribution and Morphologymentioning

confidence: 99%

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ALMA observations of molecular tori around massive black holes

Combes

García‐Burillo

Audibert

et al. 2019

A&A

208

243

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We report Atacama Large Millimeter/submillimeter Array (ALMA) observations of CO(3-2) emission in a sample of seven Seyfert/LINER galaxies at the unprecedented spatial resolution of 0 . 1 = 4-9 pc. Our aim is to explore the close environment of active galactic nuclei (AGN), and the dynamical structures leading to their fueling, through the morphology and kinematics of the gas inside the sphere of influence of the black hole. The selected galaxies host low-luminosity AGN and have a wide range of activity types (Seyferts 1 to 2, LINERs), and barred or ringed morphologies. The observed maps reveal the existence of circumnuclear disk structures, defined by their morphology and decoupled kinematics, in most of the sample. We call these structures molecular tori, even though they often appear as disks without holes in the center. They have varying orientations along the line of sight, unaligned with the host galaxy orientation. The radius of the tori ranges from 6 to 27 pc, and their mass from 0.7 × 10 7 to 3.9 × 10 7 M . The most edge-on orientations of the torus correspond to obscured Seyferts. In only one case (NGC 1365), the AGN is centered on the central gas hole of the torus. On a larger scale, the gas is always piled up in a few resonant rings 100 pc in scale that play the role of a reservoir to fuel the nucleus. In some cases, a trailing spiral is observed inside the ring, providing evidence for feeding processes. More frequently, the torus and the AGN are slightly off-centered with respect to the bar-resonant ring position, implying that the black hole is wandering by a few 10 pc amplitude around the center of mass of the galaxy. Our spatial resolution allows us to measure gas velocities inside the sphere of influence of the central black holes. By fitting the observations with different simulated cubes, varying the torus inclination and the black hole mass, it is possible to estimate the mass of the central black hole, which is in general difficult for such late-type galaxies, with only a pseudo-bulge. In some cases, AGN feedback is revealed through a molecular outflow, which will be studied in detail in a subsequent article.

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Section: Molecular Gas Distribution and Morphologymentioning

confidence: 99%

“…This may be explained by a clumpy torus. Nardini et al (2015) examine NGC 1365 during a Compton-thick state, but NGC 1365 is a well-known "changing-look" AGN (Matt et al 2003). In NGC 1566, Kawamuro et al (2013) find a NH column of ∼3 × 10 22 cm −2 (with a 26% covering fraction).…”

Section: Masses Of Possible Torimentioning

confidence: 99%

ALMA observations of molecular tori around massive black holes

Combes

García‐Burillo

Audibert

et al. 2019

A&A

208

243

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“…-APEC: thermal diffuse emission at soft X-rays arising from the host galaxy in the cases when the star formation rate is enhanced and/or from gas photoionized by the AGN in the narrow line region (see Nardini et al 2015, for the reference case of NGC 1365, and references therein for other notable sources). The parameters of this model that were varied during the simulations are the temperature of the gas (kT ) and its abundance in solar units (from Grevesse & Sauval 1998).…”

Section: Simulation Set-upmentioning

confidence: 99%

Testing the accuracy of reflection-based supermassive black hole spin measurements in AGN

Kammoun

Nardini

Risaliti

2018

A&A

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Context. X-ray reflection is a very powerful method to assess the spin of supermassive black holes (SMBHs) in active galactic nuclei (AGN), yet this technique is not universally accepted. Indeed, complex reprocessing (absorption, scattering) of the intrinsic spectra along the line of sight can mimic the relativistic effects on which the spin measure is based. Aims. In this work, we test the reliability of SMBH spin measurements that can currently be achieved through the simulations of high-quality XMM-Newton and NuSTAR spectra. Methods. Each member of our group simulated ten spectra with multiple components that are typically seen in AGN, such as warm and (partial-covering) neutral absorbers, relativistic and distant reflection, and thermal emission. The resulting spectra were blindly analysed by the other two members.Results. Out of the 60 fits, 42 turn out to be physically accurate when compared to the input model. The SMBH spin is retrieved with success in 31 cases, some of which (9) are even found among formally inaccurate fits (although with looser constraints). We show that, at the high signal-to-noise ratio assumed in our simulations, neither the complexity of the multi-layer, partial-covering absorber nor the input value of the spin are the major drivers of our results. The height of the X-ray source (in a lamp-post geometry) instead plays a crucial role in recovering the spin. In particular, a success rate of 16 out of 16 is found among the accurate fits for a dimensionless spin parameter larger than 0.8 and a lamp-post height lower than five gravitational radii.

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“…Compton-thick absorption. NGC 1365 has been observed several times in a reflection-dominated state below 10 keV (Risaliti et al 2005(Risaliti et al , 2007(Risaliti et al , 2009aBraito et al 2015;Nardini et al 2015). These states are easily identified through the high equivalent width (EW > 1 keV) iron emission line at 6.4 keV, and the relatively faint, flat continuum ( Fig.…”

Section: The Multi Component Circumnuclear Medium In Ngc 1365mentioning

confidence: 98%

Absorption from a multi‐layer circumnuclear medium and reflection from the accretion disc in NGC 1365

Risaliti

2016

Astron Nachr

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NGC 1365 hosts an X-ray obscured AGN known for both its variable absorption and its relativistic features in the reflection component. Recent simultaneous observations performed by XMM-Newton and NuSTAR caught the source in a rare, nearly unobscured state, revealing the presence of a warm absorber and a neutral, but low column density (∼ 10 22 cm −2 ) absorber, usually not observable due to thicker layers along the line of sight. Here I propose a multi-layer structure of the circumnuclear medium which can explain all the observed absorption states of this source, and their variability properties. Remarkably, despite the spectral complexity due to this multi-component absorber, the relativistic reflection component (and hence the black hole spin) can be unambiguously measured through a time resolved spectroscopic analysis.

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Platform Diving:

Cited by 8 publications

References 0 publications

ALMA observations of molecular tori around massive black holes

ALMA observations of molecular tori around massive black holes

Testing the accuracy of reflection-based supermassive black hole spin measurements in AGN

Absorption from a multi‐layer circumnuclear medium and reflection from the accretion disc in NGC 1365

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