Evidence for A Hot Wind from High-resolution X-Ray Spectroscopic Observation of the Low-luminosity Active Galactic Nucleus in NGC 7213

Shi, Fangzheng; Zhu, Bocheng; Li, Zhiyuan; Yuan, Feng

doi:10.3847/1538-4357/ac4789

Cited by 9 publications

(7 citation statements)

References 45 publications

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“…It should be noted that this fraction may also suffer uncertainties in the timescales for transitioning from an active to an inactive state. Of the currently observed TDEs, several candidates are situated within low-luminosity AGNs (e.g., Blanchard et al 2017;Yan & Xie 2018;Liu et al 2020;Shi et al 2022;Homan et al 2023), which support our predictions. Further observations of TDEs and their host galaxies in the time-domain era can shed light on the relationship between SMBH activities and the evolution of the galactic nuclear environment.…”

Section: Discussionsupporting

confidence: 85%

An Explanation for the Overrepresentation of Tidal Disruption Events in Post-starburst Galaxies

Wang,

Ma,

et al. 2023

ApJ

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Tidal disruption events (TDEs) provide a valuable probe for studying the dynamics of stars in the nuclear environments of galaxies. Recent observations show that TDEs are strongly overrepresented in post-starburst or “green valley” galaxies, although the underlying physical mechanism remains unclear. Considering the possible interaction between stars and active galactic nucleus (AGN) disks, the TDE rates can be greatly changed compared to those in quiescent galactic nuclei. In this work, we revisit TDE rates by incorporating an evolving AGN disk within the framework of “loss cone” theory. We numerically evolve the Fokker–Planck equations by considering star–disk interactions, in situ star formation in the unstable region of the outer AGN disk, and evolution of the accretion process of supermassive black holes. We find that the TDE rates are enhanced by about 2 orders of magnitude shortly after the AGN transitions into an inactive stage. During this phase, the accumulated stars rapidly scatter into the loss cone due to the disappearance of the inner standard thin disk. Our results provide an explanation for the overrepresentation of TDEs in post-starburst galaxies.

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Section: Discussionsupporting

confidence: 85%

An Explanation for the Overrepresentation of Tidal Disruption Events in Post-starburst Galaxies

Wang,

Ma,

et al. 2023

ApJ

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“…This can be substantially relevant for galaxy evolution studies, since lowpower radio jets may represent a major but underestimated source of kinetic feedback in galaxies (e.g. May et al 2018;Tabatabaei et al 2018;Fernández-Ontiveros et al 2020;Shi et al 2022;Papachristou et al 2021;Girdhar et al 2022).…”

Section: An Undeveloped Jetmentioning

confidence: 99%

Compact jets dominate the continuum emission in low-luminosity active galactic nuclei

Fernández-Ontiveros

Prieto

2023

A&A

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Low-luminosity active galactic nuclei (LLAGN) are special among their kind due to the profound structural changes that the central engine experiences at low accretion rates ( 10 −3 in Eddington units). The disappearance of the accretion disc -the blue bumpleaves behind a faint optical nuclear continuum whose nature has been largely debated. This is mainly due to serious limitations on the observational side imposed by the starlight contamination from the host galaxy and the absorption by hydrogen, preventing the detection of these weak nuclei in the infrared (IR) to ultraviolet (UV) range. We addressed these challenges by combining multiwavelength sub-arcsecond resolution observations -able to isolate the genuine nuclear continuum -with nebular lines in the mid-IR, which allowed us to indirectly probe the shape of the extreme UV continuum. We found that eight of the nearest prototype LLAGN are compatible with pure compact jet emission over more than ten orders of magnitude in frequency. This consists of self-absorbed synchrotron emission from radio to the UV plus the associated synchrotron self-Compton component dominating the emission in the UV to X-ray range. Additionally, the LLAGN continua show two particular characteristics when compared with the typical jet spectrum seen in radio galaxies: i) a very steep spectral slope in the IR-to-optical/UV range (−3.7 < α 0 < −1.3; F ν ∝ ν α 0 ); and ii) a very high turnover frequency (0.2-30 THz; 1.3 mm-10 μm) that separates the optically thick radio emission from the optically thin continuum in the IR-to-optical/UV range. These attributes can be explained if the synchrotron continuum is mainly dominated by thermalised particles at the jet base or the corona with considerably high temperatures, whereas only a small fraction of the energy (∼ 20%) would be distributed along the high-energy power-law tail of accelerated particles. On the other hand, the nebular gas excitation in LLAGN is in agreement with photo-ionisation from inverse Compton radiation (α x ∼ −0.7), which would dominate the nuclear continuum shortwards of ∼ 3000 Å, albeit a possible contribution from low-velocity shocks (< 500 km s −1 ) to the line excitation cannot be discarded. No sign of a standard hot accretion disc is seen in our sample of LLAGN, nevertheless, a weak cold disc (< 3000 K) is detected at the nucleus of the Sombrero galaxy, though its contribution to the nebular gas excitation is negligible. Our results suggest that the continuum emission in LLAGN is dominated at all wavelengths by undeveloped jets, powered by a thermalised particle distribution with high energies, on average. This is in agreement with their compact morphology and their high turnover frequencies. This behaviour is similar to that observed in peaked-spectrum radio sources and also compact jets in quiescent black hole X-ray binaries. Nevertheless, the presence of extended jet emission at kiloparsec scales for some of the objects in the sample is indicative of past jet activity, suggesting that these nuclei may undergo a r...

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“…In the latter case, an energetic wind is a generic prediction by theories and numerical simulations of hot accretion flows (Blandford & Begelman 1999;Narayan et al 2012;Yuan et al 2012Yuan et al , 2015. Direct observational evidence for such a wind was recently found in M81 * (Shi et al 2021), a prototype LLAGN, and the LLAGN in NGC 7213 (Shi et al 2022). Launching from the coronal region of the hot accretion flow, the wind has a wide opening angle, which is different from a jet that is highly collimated.…”

Section: Discussionmentioning

confidence: 93%

“…In particular, in the influential cosmological simulations of galaxy formation and evolution, IllustrisTNG (Weinberger et al 2017;Pillepich et al 2018), a kinetic feedback mode mimicking an isotropic wind from weakly accreting SMBHs is invoked to quench star formation in intermediatemass to high-mass galaxies. On the observational side, however, direct evidence for LLAGN-driven hot winds is still limited (Shi et al 2021(Shi et al , 2022. Moreover, it remains unclear whether and how an efficient kinetic feedback is materialized by the most dormant SMBHs, such as the one hosted by our own Galaxy, commonly known as Sgr A * .…”

Section: Introductionmentioning

confidence: 99%

Searching for Radio Outflows from M31* with VLBI Observations

Peng

Sjouwerman

et al. 2023

ApJ

Self Cite

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As one of the nearest and most dormant supermassive black holes (SMBHs), M31* provides a rare but promising opportunity for studying the physics of black hole accretion and feedback at the quiescent state. Previous Karl G. Jansky Very Large Array (VLA) observations with an arcsecond resolution have detected M31* as a compact radio source over centimeter wavelengths, but the steep radio spectrum suggests optically thin synchrotron radiation from an outflow driven by a hot accretion flow onto the SMBH. Aiming to probe the putative radio outflow, we conducted milliarcsecond-resolution very long baseline interferometric (VLBI) observations of M31* in 2016, primarily at 5 GHz and combining the Very Long Baseline Array, Tianma 65 m, and Shanghai 25 m radio telescopes. Despite the unprecedented simultaneous resolution and sensitivity achieved, no significant (≳3σ) signal is detected at the putative position of M31* given an rms level of 5.9 μJy beam−1, thus ruling out a pointlike source with a peak flux density comparable to that (∼30 μJy beam−1) measured by the VLA observations taken in 2012. We disfavor the possibility that M31* has substantially faded since 2012, in view that a 2017 VLA observation successfully detected M31* at a historically high peak flux density (∼75 μJy beam−1 at 6 GHz). Instead, the nondetection of the VLBI observations is best interpreted as the arcsecond-scale core being resolved out at the milliarcsecond scale, suggesting an intrinsic size of M31* at 5 GHz larger than ∼300 times the Schwarzschild radius. Such extended radio emission may originate from a hot wind driven by the weakly accreting SMBH.

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Evidence for A Hot Wind from High-resolution X-Ray Spectroscopic Observation of the Low-luminosity Active Galactic Nucleus in NGC 7213

Cited by 9 publications

References 45 publications

An Explanation for the Overrepresentation of Tidal Disruption Events in Post-starburst Galaxies

An Explanation for the Overrepresentation of Tidal Disruption Events in Post-starburst Galaxies

Compact jets dominate the continuum emission in low-luminosity active galactic nuclei

Searching for Radio Outflows from M31* with VLBI Observations

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