371 citations · 486 across the 31 of their papers we have counts for
31 papers · 1 filter
Tracking down the broadband polarimetric properties of PG 1553+113
Riccardo Middei, Svetlana G. Jorstad, Alan P. Marscher +78
We report on a nine-month monitoring campaign of the blazar PG 1553+113, relying on three observations carried out in 2025 with the Imaging X-ray Polarimetry Explorer (IXPE) and su…
X-ray spectroscopy mass constraints on V1674 Her: the fastest nova does not have a near-Chandrasekhar white dwarf
Tekeba Olbemo, Manel Errando, Andrea Gokus
V1674 Her (Nova Her 2021) is the fastest classical nova ever recorded, with an optical decline time of day, typically interpreted as evidence for a white dwarf mass cl…
Recurrence plot analysis of blazar gamma-ray light curves: Exploiting the time-domain capabilities of Fermi-LAT
Andrea Gokus, Rebecca Phillipson
Variability studies of jetted AGN, in particular blazars, have been used to gain a better understanding of the particle acceleration mechanisms in jets. However, statistical method…
The IXPE and multifrequency polarimetric view of the extreme blazars 1ES 1101-232 and RGB J0710+591
Fabrizio Tavecchio, Dawoon E. Kim, Gabriel Emery +53
Multiwavelength polarimetry is a powerful tool to probe magnetic field and flow geometries in the relativistic jets of blazars. In this respect, particularly interesting are the so…
High-energy variability of the gravitationally lensed blazar PKS 1830-211
Sarah M. Wagner, Jeffrey D. Scargle, Greg Madejski +4
The production site and process responsible for the highly variable high-energy emission observed from blazar jets are still debated. Gravitational lenses can be used as microscope…
BlazEr1: The eROSITA Blazar Catalog. Blazars and Blazar Candidates in the First eROSITA Survey
S. Haemmerich, A. Gokus, F. McBride +28
Aims. eROSITA, on board the Spectrum Roentgen Gamma (SRG) spacecraft, performed its first X-ray all-sky survey (eRASS1) between December 2019 and June 2020. It detected about 93000…
Polarization Dynamics of X-Ray Synchrotron Emission from a Multi-Zone Blazar Jet
Benjamin de Jonge, Haocheng Zhang, Manel Errando +2
The polarization of X-ray synchrotron emission in blazars directly probes the magnetic field geometry and particle acceleration processes in relativistic jets. We use particle-in-c…
The most distant -ray flare to date: a multiwavelength campaign on the blazar GB6 B1428+4217
Andrea Gokus, Manel Errando, Ivan Agudo +12
In November 2023, the Fermi Large Area Telescope detected a -ray flare from the high-redshift blazar GB6 B1428+4217 (). We initiated a multi-wavelength follow-up campai…
Unveiling blazar synchrotron emission: a multiwavelength polarimetric study of HSP and LSP populations
Sara Capecchiacci, Ioannis Liodakis, Riccardo Middei +96
Polarimetric properties of blazars allow us to put constraints on the acceleration mechanisms that fuel their powerful jets. By studying the multiwavelength polarimetric behaviour…
IXPE Observations of the Blazar Mrk 501 in 2022: A Multiwavelength View
L. Lisalda, E. Gau, H. Krawczynski +157
The blazar Markarian 501 (Mrk 501) was observed on three occasions over a 4-month period between 2022 March and 2022 July with the Imaging X-ray Polarimetry Explorer (IXPE). In thi…
Very-high-energy gamma-ray detection and long-term multi-wavelength view of the flaring blazar B2 1811+31
K. Abe, S. Abe, J. Abhir +231
Among the blazars whose emission has been detected up to very-high-energy (VHE; 100 GeV < E < 100 TeV) gamma rays, intermediate synchrotron-peaked BL Lacs (IBLs) are quite rare. Th…
New TeV-emitting BL Lac candidates from the eROSITA X-ray survey
Cassidy Metzger, Andrea Gokus, Manel Errando
TeV-emitting BL Lac type blazars represent the extreme end of the blazar population. They are characterized by relatively weak jets and radiatively inefficient accretion disks. Par…
A gamma-ray flare from TXS 1508+572: characterizing the jet of a blazar in the early Universe
Andrea Gokus, Markus Böttcher, Manel Errando +13
Blazars can be detected from very large distances due to their high luminosity. However, the detection of -ray emission of blazars beyond has only been confirmed for a sma…
Very-long-baseline interferometry study of the flaring blazar TXS 1508+572 in the early Universe
P. Benke, A. Gokus, M. Lisakov +7
High-redshift blazars provide valuable input to studies of the evolution of active galactic nuclei (AGN) jets and provide constraints on cosmological models. Detections at high ene…
Rapid Variability of Mrk 421 During Extreme Flaring as Seen Through the Eyes of XMM-Newton
A. Gokus, J. Wilms, M. Kadler +31
By studying the variability of blazars across the electromagnetic spectrum, it is possible to resolve the underlying processes responsible for rapid flux increases, so-called flare…
The SRG/eROSITA all-sky survey: First X-ray catalogues and data release of the western Galactic hemisphere
A. Merloni, G. Lamer, T. Liu +142
The eROSITA telescope array aboard the Spektrum Roentgen Gamma (SRG) satellite began surveying the sky in December 2019, with the aim of producing all-sky X-ray source lists and sk…
TELAMON: Effelsberg monitoring of AGN jets with very-high-energy astroparticle emission -- I. Program description and sample characterization
F. Eppel, M. Kadler, J. Heßdörfer +23
Aims. We introduce the TELAMON program which is using the Effelsberg 100-m telescope to monitor the radio spectra of active galactic nuclei (AGN) under scrutiny in astroparticle ph…
eROSITA Detection of a Cloud Obscuration Event in the Seyfert AGN EC 04570-5206
Alex Markowitz, Mirko Krumpe, David Homan +13
Recent years have seen broad observational support for the presence of a clumpy component within the circumnuclear gas around SMBHs. In the X-ray band, individual clouds can manife…
Insights into the broad-band emission of the TeV blazar Mrk 501 during the first X-ray polarization measurements
S. Abe, J. Abhir, V. A. Acciari +260
We present the first multi-wavelength study of Mrk 501 including very-high-energy (VHE) gamma-ray observations simultaneous to X-ray polarization measurements from the Imaging X-ra…
The High Energy X-ray Probe (HEX-P): the most powerful jets through the lens of a superb X-ray eye
Lea Marcotulli, Marco Ajello, Markus Böttcher +20
A fraction of the active supermassive black holes at the centers of galaxies in our Universe are capable of launching extreme kiloparsec-long relativistic jets. These jets are know…
TELAMON: Effelsberg Monitoring of AGN Jets with Very-High-Energy Astroparticle Emissions -- Polarization properties
J. Heßdörfer, M. Kadler, P. Benke +33
We present recent results of the TELAMON program, which is using the Effelsberg 100-m telescope to monitor the radio spectra of active galactic nuclei (AGN) under scrutiny in astro…
Multiwavelength study of extreme variability in LEDA 1154204: A changing-look event in a type 1.9 Seyfert
T. Saha, A. Markowitz, D. Homan +16
Context. Multiwavelength studies of transients in actively accreting supermassive black holes have revealed that large-amplitude variability is frequently linked to significant cha…
The peculiar variable X-ray spectrum of the active galactic nucleus PKS 2005-489
Owen Chase, Felicia McBride, Andrea Gokus +4
PKS 2005-489 is a well-known, bright southern BL Lac object that has been detected up to TeV energies. In a low-flux state it exhibits the expected multiwavelength double-peaked sp…
VLBI Scrutiny of a New Neutrino-Blazar Multiwavelength-Flare Coincidence
F. Eppel, M. Kadler, E. Ros +20
In the past years, evidence has started piling up that some high-energy cosmic neutrinos can be associated with blazars in flaring states. On February 26, 2022, a new blazar-neutri…