Possible Origin of Radio Emission From Nonthermal Electrons in Hot Accretion Flows for Low-Luminosity Active Galactic Nuclei

Liu, Hu; Wu, Qingwen

doi:10.1088/0004-637x/764/1/17

Cited by 33 publications

(30 citation statements)

References 88 publications

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“…It is known that the compact radio emission in LLAGN is underpredicted by models which only incorpo-ν (Hz) νL ν (erg s −1 ) Reference rate a thermal distribution of electrons in the RIAF (e.g. Yu et al 2011;Liu & Wu 2013;Nemmen et al 2014) and we find the same behavior here for NGC 315 as well as NGC 4261. By including the synchrotron emission of a relativistic jet modeled following Nemmen et al (2014), the radio emission can be accounted for, as the figure illustrates.…”

Section: Resultssupporting

confidence: 80%

Gamma-ray observations of low-luminosity active galactic nuclei

Menezes

Nemmen

Finke

et al. 2020

Monthly Notices of the Royal Astronomical Society

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The majority of the activity around nearby (z ≈ 0) supermassive black holes is found in low-luminosity active galactic nuclei (LLAGN), the most of them being classified as low ionization nuclear emission regions. Although these sources are well studied from radio up to X-rays, they are poorly understood in γ-rays. In this work we take advantage of the all sky-surveying capabilities of the Large Area Telescope on board Fermi Gamma ray Space Telescope to study the whole Palomar sample of LLAGN in γ-rays. Precisely, the four radio-brightest LLAGN in the sample are identified as significant γ-ray emitters, all of which are recognized as powerful Fanaroff-Riley I galaxies. These results suggest that the presence of powerful radio jets is of substantial importance for observing a significant γ-ray counterpart even if these jets are misaligned with respect to the line of sight. We also find that most of the X-ray-brightest LLAGN do not have a significant γ-ray and strong radio emission, suggesting that the X-rays come mainly from the accretion flow in these cases. A detailed analysis of the spectral energy distributions (SEDs) of NGC 315 and NGC 4261, both detected in γ-rays, is provided where we make a detailed comparison between the predicted hadronic γ-ray emission from a radiatively inefficient accretion flow (RIAF) and the γ-ray emission from a leptonic jet-dominated synchrotron self-Compton (SSC) model. Both SEDs are better described by the SSC model while the RIAF fails to explain the γ-ray observations.

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Section: Resultssupporting

confidence: 80%

Gamma-ray observations of low-luminosity active galactic nuclei

Menezes

Nemmen

Finke

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…This is especially the case for the value of δ (for a brief summary see Xie & Yuan 2012). From the detailed modelling to the spectrum of various sources, the value of δ was found to range from δ ≈ 0.5 in the case of Sgr A* (Yuan, Quataert & Narayan 2003) to δ ≈ 0.1 in the case of some LLAGNs (Yu et al 2011;Liu & Wu 2013). This could be due to, e.g., the configuration of magnetic field in the fuelling plasma in various objects being different.…”

Section: Hot Accretion Flowmentioning

confidence: 98%

Correlation between the photon index and X-ray luminosity of black hole X-ray binaries and active galactic nuclei: observations and interpretation

Yang

Xie

Yuan

et al. 2014

Monthly Notices of the Royal Astronomical Society

123

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We investigate the observed correlation between the 2-10 keV X-ray luminosity (in unit of the Eddington luminosity; l X ≡ L X /L Edd ) and the photon index (Γ) of the X-ray spectrum for both black hole X-ray binaries (BHBs) and active galactic nuclei (AGNs). We construct a large sample, with 10 −9 < ∼ l X < ∼ 10 −1 . We find that Γ is positively and negatively correlated with l X when l X > ∼ 10 −3 and 10 −6.5 < ∼ l X < ∼ 10 −3 respectively, while Γ is nearly a constant when l X < ∼ 10 −6.5 . We explain the above correlation in the framework of a coupled hot accretion flow -jet model. The radio emission always come from the jet while the X-ray emission comes from the accretion flow and jet when l X is above and below 10 −6.5 , respectively. More specifically, we assume that with the increase of mass accretion rate, the hot accretion flow develops into a clumpy and further a disc -corona two-phase structure because of thermal instability. We argue that such kind of two-phase accretion flow can explain the observed positive correlation.

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“…Due to the low Eddington ratios of M87, we adopt the ADAF model that is widely used in modeling the SED of the quiescent and low-luminosity AGNs (e.g., Ichimaru 1977;Abramowicz et al 1995;Narayan & Yi 1995;Yuan et al 2003;Wu & Cao 2006;Wu et al 2007;Ho 2008;Wu et al 2013;Liu & Wu 2013;Cao et al 2014). The global structure and dynamics of the accretion flow in general relativistic frame is calculated numerically to obtain the ion and electron temperature, density at each radius, since that the BH may be fast rotating in M87.…”

Section: Accretion-jet Modelmentioning

confidence: 99%

An Accretion-Jet Model for M87: Interpreting the Spectral Energy Distribution and Faraday Rotation Measure

Feng

2016

ApJ

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M87 is arguably the best supermassive black hole (BH) to explore the jet and/or accretion physics due to its proximity and fruitful high-resolution multi-waveband observations. We model the multiwavelength spectral energy distribution (SED) of M87 core that observed at a scale of 0.4 arcsec (∼ 10 5 R g , R g is gravitational radius) as recently presented by Prieto et al. Similar to Sgr A*, we find that the millimeter bump as observed by Atacama Large Millimeter/submillimeter Array (ALMA) can be modeled by the synchrotron emission of the thermal electrons in advection dominated accretion flow (ADAF), while the low-frequency radio emission and X-ray emission may dominantly come from the jet. The millimeter radiation from ADAF dominantly come from the region within 10R g , which is roughly consistent with the recent very long baseline interferometry observations at 230 GHz. We further calculate the Faraday rotation measure (RM) from both ADAF and jet models, and find that the RM predicted from the ADAF is roughly consistent with the measured value while the RM predicted from the jet is much higher if jet velocity close to the BH is low or moderate (e.g., v jet 0.6 c). With the constraints from the SED modeling and RM, we find that the accretion rate close to the BH horizon isBondi accretion rate), where the electron density profile, n e ∝ r ∼−1 , in the accretion flow is consistent with that determined from X-ray observation inside the Bondi radius and recent numerical simulations.

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Possible Origin of Radio Emission From Nonthermal Electrons in Hot Accretion Flows for Low-Luminosity Active Galactic Nuclei

Cited by 33 publications

References 88 publications

Gamma-ray observations of low-luminosity active galactic nuclei

Gamma-ray observations of low-luminosity active galactic nuclei

Correlation between the photon index and X-ray luminosity of black hole X-ray binaries and active galactic nuclei: observations and interpretation

An Accretion-Jet Model for M87: Interpreting the Spectral Energy Distribution and Faraday Rotation Measure

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