The curious activity in the nucleus of NGC 4151: jet interaction causing variability?

Williams, D.; Baldi, Ranieri D.; McHardy, I. M.; Beswick, R.; Panessa, F.; May, D.; Moldón, J.; Argo, M. K.; Bruni, G.; Dullo, Bililign T.; Knapen, Johan H.; Brinks, E.; Fenech, Danielle; Mundell, C. G.; Muxlow, T. W. B.; Pahari, Mayukh; Westcott, Jonathan

doi:10.1093/mnras/staa1152

Cited by 11 publications

(5 citation statements)

References 49 publications

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“…in the high-resolution, K-band subparsec (∼0.1 pc) spatial scale. The interesting jet/outflow structures of NGC 4151 were previously reported in various subparsec-to-parsec-scale VLBI and eMERLIN studies (Ulvestad et al 2005;Williams et al 2017Williams et al , 2020. While plotting SEDs using only the C-and Xband peak intensities and integrated flux densities, we found flat to slightly steeper spectra, suggesting that the central region is a compact point source.…”

Section: Resultssupporting

confidence: 77%

FRAMEx. V. Radio Spectral Shape at Central Subparsec Region of Active Galactic Nuclei

Shuvo,

Johnson,

Secrest

et al. 2024

ApJ

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We present results from the Very Long Baseline Array multifrequency (1.6, 4.4, 8.6, and 22 GHz), high-sensitivity (∼25 μJy beam−1), subparsec-scale (<1 pc) observations and spectral energy distributions for a sample of 12 local active galactic nuclei (AGNs), a subset from our previous volume-complete sample with hard-X-ray (14–195 keV) luminosities above 1042 erg s−1, out to a distance of 40 Mpc. All 12 of the sources presented here were detected in the C (4.4 GHz) and X (8.6 GHz) bands, 75% in the L band (1.6 GHz), and 50% in the K band (22 GHz). Most sources showed compact, resolved/slightly resolved, central subparsec-scale radio morphology, except for a few with extended outflow-like features. A couple of sources have an additional component that may indicate the presence of a dual-core, single or double-sided jet or a more intricate feature, such as radio emission resulting from interaction with the nearby interstellar medium. The spectral slopes are mostly gigahertz-peaked or curved, with a few showing steep, flat, or inverted spectra. We found that at the subparsec scale, the gigahertz-peaked spectra belong to the low-accreting, radio-loud AGNs, with a tendency to produce strong outflows, possibly small-scale jets, and/or have a coronal origin. In contrast, flat/inverted spectra suggest compact radio emission from the central regions of highly accreting AGNs, possibly associated with radio-quiet AGNs producing winds/shocks or nuclear star formation in the vicinity of black holes.

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Section: Resultssupporting

confidence: 77%

FRAMEx. V. Radio Spectral Shape at Central Subparsec Region of Active Galactic Nuclei

Shuvo,

Johnson,

Secrest

et al. 2024

ApJ

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“…Radio variability may also arise from jet deflection or interaction with a dense ambient medium (Middelberg et al 2007;Kunert-Bajraszewska et al 2010;An et al 2013;Mukherjee et al 2016;Siemiginowska et al 2016;Lister et al 2020;Williams et al 2020). In such scenarios, brightening in the radio may be caused by an increased Doppler factor and/or the production of shocks associated with the jet plowing into the ISM.…”

Section: Interaction With a Dense Ismmentioning

confidence: 99%

Quasars That Have Transitioned from Radio-quiet to Radio-loud on Decadal Timescales Revealed by VLASS and FIRST

Nyland

Dong

Patil

et al. 2020

ApJ

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We have performed a search over 3440 deg 2 of Epoch 1 (2017-2019) of the Very Large Array Sky Survey to identify unobscured quasars in the optical (0.2<z<3.2) and obscured active galactic nuclei (AGNs) in the infrared that have brightened dramatically in the radio over the past one to two decades. These sources would have been previously classified as "radio-quiet" quasars based on upper limits from the Faint Images of the Radio Sky at Twenty cm survey (1993-2011), but they are now consistent with "radio-loud" quasars ( -= -L 10 erg s 3 GHz 40 42 1). A quasi-simultaneous, multiband (∼1-18 GHz) follow-up study of 14 sources with the VLA has revealed compact sources (<0 1 or <1 kpc) with peaked radio spectral shapes. The highamplitude variability over decadal timescales at 1.5 GHz (100% to >2500%) but roughly steady fluxes over a few months at 3 GHz are inconsistent with extrinsic variability due to propagation effects, thus favoring an intrinsic origin. We conclude that our sources are powerful quasars hosting compact/young jets. This challenges the generally accepted idea that "radio-loudness" is a property of the quasar/AGN population that remains fixed on human timescales. Our study suggests that frequent episodes of short-lived AGN jets that do not necessarily grow to large scales may be common at high redshift. We speculate that intermittent but powerful jets on subgalactic scales could interact with the interstellar medium, possibly driving feedback capable of influencing galaxy evolution.

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“…However, while NGC 1068 is a starburst galaxy, NGC 4151 shows little evidence of star formation (Mundell et al 1999). Both sources show evidence of jet-disk interaction (Venturi, G. et al 2021;Williams et al 2020). The relativistic jets and the accretion disk are the two most promising sites for efficient particle acceleration, essential for neutrino production.…”

Section: Discussionmentioning

confidence: 99%

Search for high-energy neutrino emission from hard X-ray AGN with IceCube

2021

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The IceCube Neutrino Observatory has detected high-energy astrophysical neutrinos in the TeV-PeV range. These neutrinos have an isotropic distribution on the sky, and therefore, likely originate from extragalactic sources. Active Galactic Nuclei form a class of astronomical objects which are promising neutrino source candidates given their high electromagnetic luminosity and potential ability to accelerate cosmic rays up to energies greater than 10 16 eV. Interactions of these cosmic rays within the AGN environment are expected to produce both neutrinos and pionic gamma rays. Some hadronic models of AGN emission suggest that such gamma rays can in turn interact with the dense photon fields of AGN and cascade down to hard X-rays and MeV gamma rays. We present an update on the IceCube stacking analysis searching for high-energy neutrinos from hard X-ray sources sampled from the Swift-BAT AGN Spectroscopic Survey.

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The curious activity in the nucleus of NGC 4151: jet interaction causing variability?

Cited by 11 publications

References 49 publications

FRAMEx. V. Radio Spectral Shape at Central Subparsec Region of Active Galactic Nuclei

FRAMEx. V. Radio Spectral Shape at Central Subparsec Region of Active Galactic Nuclei

Quasars That Have Transitioned from Radio-quiet to Radio-loud on Decadal Timescales Revealed by VLASS and FIRST

Search for high-energy neutrino emission from hard X-ray AGN with IceCube

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