Accretion and jets in a low-luminosity AGN: the nucleus of NGC 1052

Falocco, S.; Larsson, Josefin; Nandi, Sumit

doi:10.1051/0004-6361/202037516

Cited by 10 publications

(13 citation statements)

References 70 publications

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“…Temporarily letting the line energy be a free parameter, we find that it is constrained to (6.39±0.01) keV, identifying it as the neutral Fe Kα line. Its equivalent width is (100 ± 10) eV, which is consistent with results from Brenneman et al (2009) and only marginally lower than the Fe Kα equivalent widths from González-Martín et al (2009), Rivers et al (2013), andFalocco et al (2020).…”

Section: Single-epoch Spectral Modelingsupporting

confidence: 86%

“…The low-energy excess peaking around 0.9 keV may be due to optically thin plasma emission, while the narrow excess at 6.4 keV reveals presence of a narrow emission line. Both features have been identified in previous studies of NGC 1052, with the former known to extend out to galactic scales (Kadler et al 2004a;Osorio-Clavijo et al 2020;Falocco et al 2020). We first add a mekal component (Mewe et al 1995) to represent the plasma emission as in the more detailed studies mentioned above, which lowers the total χ 2 to 1491.9.…”

Section: Single-epoch Spectral Modelingmentioning

confidence: 96%

“…Much of the existing soft X-ray data has previously been analyzed and presented in the literature. In particular, soft X-ray diffuse emission in NGC 1052 has been studied using Chandra data by Kadler et al (2004a) and most recently by Osorio-Clavijo et al (2020) and Falocco et al (2020). These works, along with some studies of larger samples that include NGC 1052 (Hernández- García et al 2013;Connolly et al 2016), also examined variability in the soft X-ray band.…”

Section: Observations and Datamentioning

confidence: 99%

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Properties of the Obscuring Torus in NGC 1052 from Multi-epoch Broadband X-ray Spectroscopy

Baloković,

Cabral,

Brenneman

et al. 2021

Preprint

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Obscuration of the innermost parts of active galactic nuclei (AGN) is observed in the majority of the population both in the nearby universe and at high redshift. However, the nature of the structures causing obscuration, especially in low-luminosity AGN, is poorly understood at present. We present a novel approach to multi-epoch broadband X-ray spectroscopy, anchored in the long-term average spectrum in the hard X-ray band, applied to the nearby, X-ray bright AGN in the galaxy NGC 1052. From spectral features due to X-ray reprocessing in the circumnuclear material, based on a simple, uniform-density torus X-ray reprocessing model, we find a covering factor of 80-100 % and a globally averaged column density in the range (1 − 2) × 10 23 cm −2 . This closely matches the independently measured variable line-of-sight column density range, leading to a straightforward and self-consistent picture of the obscuring torus in NGC 1052, similar to several other AGN in recent literature. Comparing this X-ray-constrained torus model with measurements of spatially resolved sub-parsec absorption from radio observations, we find that it may be possible to account for both X-ray and radio data with a torus model featuring a steep density gradient along the axis of the relativistic jets. This provides a valuable direction for the development of improved physical models for the circumnuclear environment in NGC 1052 and potentially in a wider class of AGN.

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Section: Single-epoch Spectral Modelingsupporting

confidence: 86%

Section: Single-epoch Spectral Modelingmentioning

confidence: 96%

Section: Observations and Datamentioning

confidence: 99%

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Properties of the Obscuring Torus in NGC 1052 from Multi-epoch Broadband X-ray Spectroscopy

Baloković,

Cabral,

Brenneman

et al. 2021

Preprint

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“…The outer extent of the plasma torus is in agreement with the location of the break in the collimation profile. In addition, NGC 1052 most likely hosts an advection-dominated accretion flow (ADAF) inside an optically thick, geometrically thin accretion disk, which is truncated at a distance of r tr ≥ 13 R S (Reb et al 2018;Falocco et al 2020). This might explain the atypical close-to-cylindrical collimation profile.…”

Section: The Collimation and Acceleration Zonementioning

confidence: 99%

Ambilateral collimation study of the twin-jets in NGC 1052

Baczko

Ros

Kadler³

et al. 2022

A&A

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Context. With the increase in the sensitivity and resolution of radio interferometry within recent years, the study of the collimation and acceleration region of extragalactic jets in active galactic nuclei (AGN) has come into focus. Whereas a large fraction of AGN jets show a change from parabolic to conical collimation profile around the Bondi radius, there is a small number of sources that display a deviation from this standard picture, including the radio galaxy NGC 1052. Aims. We study the jet width profile, which provides valuable information about the interplay between the central engine and accretion disk system and the formation, acceleration, and collimation of the jets. Methods. We observed the double-sided, low-radio-power active galaxy NGC 1052 at six frequencies with the VLBA in 2017 and at 22 GHz with RadioAstron in 2016. These data are combined with archival 15, 22, and 43 GHz multi-epoch VLBA observations. From ridge-line fitting we obtained width measurements along the jet and counter-jet which were fitted with single and broken power laws. Results. We find a clear break point in the jet collimation profile at ∼104 RS (Schwarzschild radii). Downstream of the break, the collimation is conical with a power-law index of 1.0 − 1.2 (cylindrical 0; parabolic 0.5; conical 1) for both jets. On the other hand, the upstream power-law index of 0.36 for the approaching jet is neither cylindrical nor parabolic, and the value of 0.16 for the receding jet suggests this latter is close-to cylindrical. For both jets we find a large opening angle of ∼30° at a distance of ∼103 RS and well-collimated structures with an opening angle of < 10° downstream of the break. Conclusions. There are significant differences between the upstream collimation profiles of the approaching (eastern) and receding (western) jets. Absorption or scattering in the surrounding torus as well as an accretion wind may mimic a cylindrical profile. We need to increase the observing frequencies, which do not suffer from absorption, in order to find the true jet collimation profile upstream of 104 RS.

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“…The outer extent of the plasma torus is in agreement with the location of the break in the collimation profile. In addition, NGC 1052 most likely hosts an Advection Dominated Accretion Flow (ADAF) inside an optically thick, geometrically thin accretion disk, truncated at a distance of r tr ≥ 13 R S (Reb et al 2018;Falocco et al 2020). This might explain the untypically close-to-cylindrical collimation profile.…”

Section: The Collimation and Acceleration Zonementioning

confidence: 99%

Ambilateral collimation study of the twin-jets in NGC1052

Baczko,

Ros,

Kadler

et al. 2021

Preprint

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Context: With the increased sensitivity and resolution of radio interferometry the study of the collimation and acceleration region of extragalactic jets in Active Galactic Nuclei (AGN) has come into focus within the last years. Whereas a large fraction of AGN jets reveal a change from parabolic to conical collimation profile around the Bondi radius, there is a small number of sources which deviates from this standard picture, including the radio galaxy NGC 1052. Aims: We study the jet width profile, which provides valuable information about the interplay between the central engine and accretion disk system and the formation, acceleration, and collimation of the jets. Methods: We observed the double-sided, low radio power active galaxy NGC 1052 at six frequencies with the VLBA in 2017 and at 22 GHz with RadioAstron in 2016. These data are combined with archival 15, 22, and 43 GHz multi-epoch VLBA observations. From ridge-line fitting we obtained width measurements along the jet and counter-jet which were fitted with single and broken power-laws. Results: We find a clear break point in the jet collimation profile at ∼ 10 4 R S (Schwarzschild radii). Downstream of the break the collimation is conical with a power-law index of 1.0 -1.2 (cylindrical 0; parabolic 0.5; conical 1) for both jets. On the other hand the upstream power-law index of 0.36 for the approaching jet is neither cylindrical nor parabolic and for the receding jet with 0.16 close-to cylindrical. For both jets we find a large opening angle of ∼ 30 • at a distance of ∼ 10 3 R S and well collimated structures with an opening angle of < 10 • downstream of the break. Conclusions: There are significant differences in the upstream collimation profile between approaching (Eastern) and receding (Western) jet. Absorption or scattering in the surrounding torus as well as an accretion wind may mimic a cylindrical profile. We need to increase the observing frequencies, which do not suffer from absorption to find the true jet collimation profile upstream of 10 4 R S .

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Accretion and jets in a low-luminosity AGN: the nucleus of NGC 1052

Cited by 10 publications

References 70 publications

Properties of the Obscuring Torus in NGC 1052 from Multi-epoch Broadband X-ray Spectroscopy

Properties of the Obscuring Torus in NGC 1052 from Multi-epoch Broadband X-ray Spectroscopy

Ambilateral collimation study of the twin-jets in NGC 1052

Ambilateral collimation study of the twin-jets in NGC1052

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