140 citations · 701 across the 25 of their papers we have counts for
26 papers
Multi-band optical photometric variability of the blazar OJ 287 from 2015 to 2025
Alok C. Gupta, Karan Dogra, Mark Kidger +101
We present the most densely sampled multi-band optical photometric observations of the peculiar BL Lacertae object OJ 287 from 2015 to 2025 with a focus on its optical activity on…
POLAMI Multi-Wavelength Polarization Study of AGN Jets: A Millimeter-Optical Comparison
C. Casadio, D. Blinov, I. Agudo +20
Millimeter-band polarimetry offers a powerful probe of AGN jets, accessing regions less affected by opacity and Faraday rotation than at longer radio wavelengths. As part of the PO…
Multiband optical variability on diverse timescales of the blazar Ton 599 from 2011 to 2023
O. Vince, C. M. Raiteri, M. Villata +72
(Shortened)Context: We analyze the optical variability of the FSRQ Ton 599 using BVRI photometry from the WEBT collaboration (2011-2023), complemented by photometric and spectrosco…
A wiggling filamentary jet at the origin of the blazar multi-wavelength behaviour
C. M. Raiteri, M. Villata, M. I. Carnerero +96
Blazars are beamed active galactic nuclei known for their strong multi-wavelength variability on timescales from years down to minutes. We aim to investigate the suitability of the…
Testing particle acceleration in blazar jets with continuous high-cadence optical polarization observations
Ioannis Liodakis, Sebastian Kiehlmann, Alan P. Marscher +44
Variability can be the pathway to understanding the physical processes in astrophysical jets, however, the high-cadence observations required to test particle acceleration models a…
Evidence of jet activity from the secondary black hole in the OJ287 binary system
Mauri J. Valtonen, Staszek Zola, Alok C. Gupta +29
We report the study of a huge optical intraday flare on November 12, 2021, at 2 am UT, in the blazar OJ287. In the binary black hole model it is associated with an impact of the se…
Multi-band Cross-correlated Radio Variability of the Blazar 3C 279
Krishna Mohana A, Alok C. Gupta, Alan P. Marscher +18
We present the results of our study of cross-correlations between long-term multi-band observations of the radio variability of the blazar 3C 279. More than a decade (2008-2022) of…
Quasi-simultaneous Optical Flux and Polarization Variability of the Binary Super Massive Black Hole Blazar OJ 287 from 2015 to 2023: Detection of an Anticorrelation in Flux and Polarization Variability
Alok C. Gupta, Pankaj Kushwaha, Mauri J. Valtonen +25
We study the optical flux and polarization variability of the binary black hole blazar OJ 287 using quasi-simultaneous observations from 2015 to 2023 carried out using telescopes i…
The Repeating Flaring Activity of Blazar AO 0235+164
Juan Escudero Pedrosa, Iván Agudo, Andrea Tramacere +27
Context. Blazar AO 0235+164, located at redshift z = 0.94, has undergone several sharp multi-spectral-range flaring episodes during the last decades. In particular, the episodes pe…
Multi-year characterisation of the broad-band emission from the intermittent extreme BL Lac 1ES~2344+514
H. Abe, S. Abe, V. A. Acciari +232
The BL Lac 1ES 2344+514 is known for temporary extreme properties (e.g., a shift of the synchrotron SED peak energy above 1keV). While those extreme states were so fa…
The optical behaviour of BL Lacertae at its maximum brightness levels: a blend of geometry and energetics
C. M. Raiteri, M. Villata, S. G. Jorstad +13
In 2021 BL Lacertae underwent an extraordinary activity phase, which was intensively followed by the Whole Earth Blazar Telescope (WEBT) Collaboration. We present the WEBT optical…
Polarized Blazar X-rays imply particle acceleration in shocks
Ioannis Liodakis, Alan P. Marscher, Iván Agudo +125
Most of the light from blazars, active galactic nuclei with jets of magnetized plasma that point nearly along the line of sight, is produced by high-energy particles, up to $\sim 1…
Kinematics of Parsec-Scale Jets of Gamma-Ray Bright Blazars at 43 GHz during Ten Years of the VLBA-BU-BLAZAR Program
Zachary R. Weaver, Svetlana G. Jorstad, Alan P. Marscher +7
We analyze the parsec-scale jet kinematics from 2007 June to 2018 December of a sample of -ray bright blazars monitored roughly monthly with the Very Long Baseline Array at 43 G…
New jet feature in the parsec-scale jet of the blazar OJ287 connected to the 2017 teraelectronvolt flaring activity
R. Lico, C. Casadio, S. G. Jorstad +16
In February 2017 the blazar OJ287, one of the best super-massive binary-black-hole-system candidates, was detected for the first time at very high energies (VHEs; E>100GeV) with th…
Emission Line Variability during a Nonthermal Outburst in the Gamma-Ray Bright Quasar 1156+295
Melissa K. Hallum, Svetlana G. Jorstad, Valeri M. Larionov +18
We present multi-epoch optical spectra of the -ray bright blazar 1156+295 (4C +29.45, Ton 599) obtained with the 4.3~m Lowell Discovery Telescope. During a multi-wavelength outb…
Radio and -ray activity in the jet of the blazar S5 0716714
Dae-Won Kim, Evgeniya V. Kravchenko, Alexander M. Kutkin +11
We explore the connection between the -ray and radio emission in the jet of the blazar 0716714 by using 15, 37, and 230 GHz radio and 0.1200 GeV -ray light curves spann…
Investigation of the correlation patterns and the Compton dominance variability of Mrk 421 in 2017
MAGIC Collaboration, V. A. Acciari, S. Ansoldi +284
We present a detailed characterisation and theoretical interpretation of the broadband emission of the paradigmatic TeV blazar Mrk 421, with special focus on the multi-band flux co…
The complex variability of blazars: Time-scales and periodicity analysis in S4 0954+65
C. M. Raiteri, M. Villata, V. M. Larionov +3
Among active galactic nuclei, blazars show extreme variability properties. We here investigate the case of the BL Lac object S4 0954+65 with data acquired in 2019-2020 by the Trans…
The jet collimation profile at high resolution in BL Lacertae
C. Casadio, N. R. MacDonald, B. Boccardi +14
Controversial studies on the jet collimation profile of BL Lacertae (BL Lac), the eponymous blazar of BL Lac objects class, complicate the scenario in this already puzzling class o…
GRB 191016A: A Long Gamma-Ray Burst Detected by TESS
Krista Lynne Smith, Ryan Ridden-Harper, Michael Fausnaugh +8
The TESS exoplanet-hunting mission detected the rising and decaying optical afterglow of GRB 191016A, a long Gamma-Ray Burst (GRB) detected by Swift-BAT but without prompt XRT or U…
VHE gamma-ray detection of FSRQ QSO B1420+326 and modeling of its enhanced broadband state in 2020
V. A. Acciari, S. Ansoldi, L. A. Antonelli +230
Context. QSO B1420+326 is a blazar classified as a Flat Spectrum Radio Quasar (FSRQ). In the beginning of 2020 it underwent an enhanced flux state. An extensive multiwavelength cam…
Observation of a sudden cessation of a very-high-energy gamma-ray flare in PKS 1510-089 with H.E.S.S. and MAGIC in May 2016
H. E. S. S. Collaboration, H. Abdalla, R. Adam +430
The flat spectrum radio quasar (FSRQ) PKS 1510-089 is known for its complex multiwavelength behavior, and is one of only a few FSRQs detected at very high energy (VHE, GeV…
Two Flares with One Shock: the Interesting Case of 3C 454.3
I. Liodakis, D. Blinov, S. G. Jorstad +18
The quasar 3C 454.3 is a blazar known for its rapid and violent outbursts seen across the electromagnetic spectrum. Using gamma-ray, X-ray, multi-band optical, and very long baseli…
Multi-Wavelength Variability of BL Lacertae Measured with High Time Resolution
Zachary R. Weaver, K. E. Williamson, S. G. Jorstad +54
In an effort to locate the sites of emission at different frequencies and physical processes causing variability in blazar jets, we have obtained high time-resolution observations…