143 citations · 829 across the 24 of their papers we have counts for
24 papers
The TeV-emitting radio galaxy 3C 264. VLBI kinematics and SED modeling
B. Boccardi, G. Migliori, P. Grandi +5
In March 2018, Mukherjee (2018) reported the detection by VERITAS of very-high-energy emission (VHE; > 100 GeV) from 3C 264. This is the sixth, and second most distant, radio galax…
F-GAMMA: Multi-frequency radio monitoring of Fermi blazars. The 2.64 to 43 GHz Effelsberg light curves from 2007-2015
E. Angelakis, L. Fuhrmann, I. Myserlis +7
The advent of the Fermi-GST with its unprecedented capability to monitor the entire 4 pi sky within less than 2-3 hours, introduced new standard in time domain gamma-ray astronomy.…
High cadence, linear and circular polarization monitoring of OJ 287 - Helical magnetic field in a bent jet
I. Myserlis, S. Komossa, E. Angelakis +5
We present a multi-frequency, dense radio monitoring program of the blazar OJ287 using the 100m Effelsberg radio telescope. We analyze the evolution in total flux density, linear a…
Scale invariant jets: from blazars to microquasars
I. Liodakis, V. Pavlidou, I. Papadakis +9
Black holes, anywhere in the stellar-mass to supermassive range, are often associated with relativistic jets. Models suggest that jet production may be a universal process common i…
Full-Stokes polarimetry with circularly polarized feeds - Sources with stable linear and circular polarization in the GHz regime
I. Myserlis, E. Angelakis, A. Kraus +8
We present a pipeline that allows recovering reliable information for all four Stokes parameters with high accuracy. Its novelty relies on the treatment of the instrumental effects…
Gaussian processes for blazar variability studies
V. Karamanavis
This article shortly introduces Gaussian processes (GP) as a new approach for modelling time series in the field of blazar physics. In the second part of the paper, recent results…
Radio and gamma-ray loud narrow-line Seyfert 1 galaxies in the spotlight
V. Karamanavis, E. Angelakis, S. Komossa +3
Narrow-line Seyfert 1 (NLS1) galaxies provide us with unique insights into the drivers of AGN activity under extreme conditions. Given their low black hole (BH) masses and near-Edd…
F-GAMMA: Variability Doppler factors of blazars from multiwavelength monitoring
I. Liodakis, N. Marchili, E. Angelakis +8
Recent population studies have shown that the variability Doppler factors can adequately describe blazars as a population. We use the flux density variations found within the exten…
Physical Conditions and Variability Processes in AGN Jets through Multi-Frequency Linear and Circular Radio Polarization Monitoring
Ioannis Myserlis, Emmanouil Angelakis, Alex Kraus +3
Radio polarimetry is an invaluable tool to investigate the physical conditions and variability processes in active galactic nuclei (AGN) jets. However, detecting their linear and c…
Inner jet kinematics and the viewing angle towards the γ-ray narrow-line Seyfert 1 galaxy 1H 0323+342
L. Fuhrmann, V. Karamanavis, S. Komossa +9
Near-Eddington accretion rates onto low-mass black holes are thought to be a prime driver of the multi-wavelength properties of the narrow-line Seyfert 1 (NLS1) population of activ…
The F-GAMMA program: Multi-frequency study of Active Galactic Nuclei in the Fermi era. Program description and the first 2.5 years of monitoring
L. Fuhrmann, E. Angelakis, J. A. Zensus +15
To fully exploit the scientific potential of the Fermi mission, we initiated the F-GAMMA program. Between 2007 and 2015 it was the prime provider of complementary multi-frequency m…
Location of Gamma-ray emission and magnetic field strengths in OJ 287
J. A. Hodgson, T. P. Krichbaum, A. P. Marscher +19
The Gamma-ray BL Lac object OJ 287 is known to exhibit inner-parsec "jet-wobbling", high degrees of variability at all wavelengths and quasi-stationary features including an appare…
What can the 2008/10 broadband flare of PKS 1502+106 tell us? Nuclear opacity, magnetic fields, and the location of gamma rays
V. Karamanavis, L. Fuhrmann, E. Angelakis +7
Context. The origin of blazar variability, seen from radio up to gamma rays, is still a heavily debated matter and broadband flares offer a unique testbed towards a better understa…
Multiwavelength Study of Quiescent States of Mrk 421 with Unprecedented Hard X-Ray Coverage Provided by NuSTAR in 2013
M. Baloković, D. Paneque, G. Madejski +305
We present coordinated multiwavelength observations of the bright, nearby BL Lac object Mrk 421 taken in 2013 January-March, involving GASP-WEBT, Swift, NuSTAR, Fermi-LAT, MAGIC, V…
PKS 1502+106: A high-redshift Fermi blazar at extreme angular resolution. Structural dynamics with VLBI imaging up to 86 GHz
V. Karamanavis, L. Fuhrmann, T. P. Krichbaum +7
Context. Blazars are among the most energetic objects in the Universe. In 2008 August, Fermi/LAT detected the blazar PKS 1502+106 showing a rapid and strong gamma-ray outburst foll…
First NuSTAR Observations of Mrk 501 within a Radio to TeV Multi-Instrument Campaign
A. Furniss, K. Noda, S. Boggs +273
We report on simultaneous broadband observations of the TeV-emitting blazar Markarian 501 between 1 April and 10 August 2013, including the first detailed characterization of the s…
Localizing the rays from blazar PKS 1502+106
Vassilis Karamanavis, L. Fuhrmann, T. P. Krichbaum +7
Blazars are among the most variable objects in the universe. They feature energetic jets of plasma that launch from the cores of these active galactic nuclei (AGN), triggering acti…
Radio jet emission from GeV-emitting narrow-line Seyfert 1 galaxies
E. Angelakis, L. Fuhrmann, N. Marchili +9
We studied the radio emission from four radio-loud and gamma-ray-loud narrow-line Seyfert 1 galaxies. The goal was to investigate whether a relativistic jet is operating at the sou…
Multi-frequency linear and circular radio polarization monitoring of jet emission elements in blazars
I. Myserlis, E. Angelakis, L. Fuhrmann +5
Radio emission in blazars -- the aligned subset of Active Galactic Nuclei (AGN) -- is produced by synchrotron electrons moving relativistically in their jet's magnetic field. Under…
An Exceptional Radio Flare in Markarian 421
Joseph L. Richards, Talvikki Hovatta, Matthew L. Lister +9
In September 2012, the high-synchrotron-peaked (HSP) blazar Markarian 421 underwent a rapid wideband radio flare, reaching nearly twice the brightest level observed in the centimet…
Multifrequency studies of the narrow-line Seyfert 1 galaxy SBS 0846+513
F. D'Ammando, M. Orienti, J. Finke +10
The narrow-line Seyfert 1 galaxy SBS 0846+513 was first detected by the Large Area Telescope (LAT) on-board Fermi in 2011 June-July when it underwent a period of flaring activity.…
Zooming towards the Event Horizon - mm-VLBI today and tomorrow
T. P. Krichbaum, A. Roy, J. Wagner +21
Global VLBI imaging at millimeter and sub-millimeter wavelength overcomes the opacity barrier of synchrotron self-absorption in AGN and opens the direct view into sub-pc scale regi…
Properties of the radio jet emission of four gamma-ray Narrow Line Seyfert 1 galaxies
E. Angelakis, L. Fuhrmann, I. Myserlis +8
The detection of gamma rays from a small number of Narrow Line Seyfert 1 galaxies by the LAT instrument onboard Fermi seriously challenged our understanding of AGN physics. Among t…
ThReT: A new survey for Extrasolar Planetary transits at Mt. Holomon, Greece
John Antoniadis, Vassilis Karamanavis, Dimitris Mislis +2
We present the instrumentation, the target selection method, the data analysis pipeline and the preliminary results of the Thessaloniki Research for Transits project (ThReT). ThReT…