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We report first results from KVN and VERA Array (KaVA) VLBI observations obtained in the frame of our Plasma-physics of Active Galactic Nuclei (PAGaN) project. We observed eight selected AGN at 22 and 43 GHz in single polarization (LCP)…

The correlation between the kinetic power $P_{\rm jet}$ and intrinsic bolometric luminosity $L_{\rm jet}$ of jets may reveal the underlying jet physics in various black hole systems. Based on the recent work by Nemmen et al. (2012), we…

High Energy Astrophysical Phenomena · Physics 2015-06-18 Renyi Ma , Fu-Guo Xie , Shujin Hou

Disk continuum reverberation mapping is one of the primary ways we learn about active galactic nuclei (AGN) accretion disks. Reverberation mapping assumes that time-varying X-rays incident on the accretion disk drive variability in…

High Energy Astrophysical Phenomena · Physics 2025-01-14 Amy Secunda , Yan-Fei Jiang , Jenny E. Greene

The two components of radio emission, above and below 86 GHz respectively, from the Galactic center source-Sgr A* can be naturally explained by the hybrid of thermal and nonthermal electrons in hot accretion flows (e.g., radiatively…

High Energy Astrophysical Phenomena · Physics 2015-06-12 Hu Liu , Qingwen Wu

The origin of the radio emission in active galactic nuclei (AGN) is still debated. Multiple physical mechanisms can contribute to the spectrum at these frequencies, including relativistic jets, the jet base, outflows, star formation, and…

High Energy Astrophysical Phenomena · Physics 2026-04-01 M. Berton , E. Järvelä , S. Chen , L. Crepaldi , I. Varglund , M. Coloma Puga , A. Jimenez-Gallardo , A. Lähteenmäki , S. Panda , C. Piscitelli , A. Tortosa

We have used the VLA to study radio variability among a sample of 18 low luminosity active galactic nuclei (LLAGNs), on time scales of a few hours to 10 days. The goal was to measure or limit the sizes of the LLAGN radio-emitting regions,…

Astrophysics · Physics 2009-11-10 James M. Anderson , James S. Ulvestad

Synchrotron self-absorption in active galactic nuclei (AGN) jets manifests itself as a time delay between flares observed at high and low radio frequencies. It is also responsible for the observing frequency dependent change in size and…

Astrophysics of Galaxies · Physics 2019-04-17 Alexander Kutkin , Ilya Pashchenko , Kirill Sokolovsky , Yuri Y. Kovalev , Margo Aller , Hugh Aller

Most of the electromagnetic output of blazars (BL Lac objects and Flat Spectrum Radio Quasars) comes out in the gamma-ray band, making the Large Area Telescope [0.1-100 GeV] onboard the Fermi satellite and the Cherenkov telescopes crucial…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 G. Ghisellini

Estimates of magnetic field strength in relativistic jets of active galactic nuclei (AGN), obtained by measuring the frequency-dependent radio core location, imply that the total magnetic fluxes in those jets are consistent with the…

High Energy Astrophysical Phenomena · Physics 2015-06-23 Krzysztof Nalewajko , Marek Sikora , Mitchell C. Begelman

The galaxy NGC 4418 contains one of the most compact obscured nuclei within a luminous infrared galaxy (LIRG) in the nearby Universe. This nucleus contains a rich molecular gas environment and an unusually high ratio of infrared to radio…

Astrophysics of Galaxies · Physics 2014-06-04 E. Varenius , J. E. Conway , I. Martí-Vidal , S. Aalto , R. Beswick , F. Costagliola , H. -R. Klöckner

We investigate statistical and individual astrophysical properties of active galactic nuclei (AGNs), such as parsec-scale flux density, core dominance, angular and linear sizes, maximum observed brightness temperatures of VLBI core…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-20 A. B. Pushkarev , Y. Y. Kovalev

An interesting feature in active galactic nuclei (AGN) accreting at low rate is the weakness of the reflection features in their X-ray spectra, which can result from the gradual disappearance of the torus with decreasing accretion rates. It…

Low excitation radio galaxies (LERGs) are weakly accreting active galactic nuclei (AGN) believed to be fuelled by radiatively inefficient accretion processes. Despite this, recent works have shown evidence for ionized and neutral hydrogen…

Astrophysics of Galaxies · Physics 2021-09-29 Mainak Singha , Christopher P. O'Dea , Yjan A. Gordon , Cameron Lawlor-Forsyth , Stefi A. Baum

Warped accretion discs in Active Galactic Nuclei (AGN) exert a torque on the black hole that tends to align the rotation axis with the angular momentum of the outer disc. We compute the magnitude of this torque by solving numerically for…

Astrophysics · Physics 2009-10-31 Priyamvada Natarajan , Philip J. Armitage

We present the multi-wavelength and environmental properties of 37 variability-selected active galactic nuclei (AGNs), including 30 low luminosity AGNs (LLAGNs), using a high cadence time-domain survey (ASAS-SN) from a spectroscopic sample…

Astrophysics of Galaxies · Physics 2025-01-30 Heechan Yuk , Xinyu Dai , Marko Mićić

Recent advancements in high-resolution Very Long Baseline Interferometry (VLBI) have significantly improved our understanding of jet collimation near supermassive black holes in active galactic nuclei (AGNs), particularly in high-power…

High Energy Astrophysical Phenomena · Physics 2025-07-30 Elika Prameswari Fariyanto , Kazuhiro Hada , Yuzhu Cui , Mareki Honma , Masanori Nakamura , Keiichi Asada , Xuezheng Wang , Wu Jiang

Plasmas of geometrically thick, black hole (BH) accretion flows in active galactic nuclei (AGNs) are generally collisionless for protons, and involve magnetic field turbulence. Under such conditions a fraction of protons can be accelerated…

High Energy Astrophysical Phenomena · Physics 2015-06-05 Kenji Toma , Fumio Takahara

Relativistic jets of radio loud active galactic nuclei (AGN) produce highly directed, intense beams of radiation. A fraction of this beamed radiation scatters on the thermal plasma generally surrounding an AGN. The morphology of the…

Astrophysics · Physics 2009-11-10 Conrad Cramphorn , Sergey Sazonov , Rashid Sunyaev

We perform a multi-band statistical analysis of core-dominated superluminal active galactic nuclei (AGN) detected with Fermi Large Area Telescope (LAT). The detection rate of $\gamma$-ray jets is found to be high for optically bright AGN.…

Cosmology and Nongalactic Astrophysics · Physics 2010-06-14 T. G. Arshakian , J. León-Tavares , J. Torrealba , V. H. Chavushyan

We investigate the nature of low-luminosity radio-loud active galactic nuclei (RLAGN) selected from the LOFAR Two-metre Sky Survey (LoTSS) first data release (DR1). Using optical, mid-infrared, and radio data, we have conservatively…

Astrophysics of Galaxies · Physics 2024-03-01 J. Chilufya , M. J. Hardcastle , J. C. S. Pierce , J. H. Croston , B. Mingo , X. Zheng , R. D. Baldi , H. J. A. Röttgering
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