140 citations · 549 across the 49 of their papers we have counts for
54 papers
A Swift X-ray view of the SMS4 sample - III: Deeper insight into previously undetected sources
Alessandro Maselli, William R. Forman, Christine Jones +2
We update the X-ray information given in Maselli et al. (2024) for five bright radio sources in the SMS4 catalog, thanks to additional observations with the X-Ray Telescope (XRT) o…
The first near-infrared high-resolution échelle spectroscopy of the outflow in NGC 4151. A study of the clouds covering the Eye of Sauron
Francesco Gabriele Saturni, Riccardo Middei, Hermine Landt +4
We present the first high-resolution near-infrared spectroscopy of the nucleus of the nearby, well-known Seyfert galaxy NGC 4151 (the "Eye of Sauron"). Past studies of this source…
Directly tracking the re-brightening of a supermassive black hole accretion disk
R. Middei, E. Nardini, C. Done +12
Accretion onto supermassive black holes powers the most luminous persistent sources in the Universe, the so-called active galactic nuclei, whose emission is characterized by two di…
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…
Ultra-thick warm absorbers: Enlarging the parameter space of AGN ionised outflows
R. Middei, E. Piconcelli, E. Nardini +9
The analysis of X-ray absorption features in active galactic nuclei (AGN) provides a wealth of information about the physical properties of the matter surrounding supermassive blac…
Magnetic-field Order in the Southwestern Rim of RCW 86 Constrained Using X-Ray Polarimetry
Stefano Silvestri, Dmitry Prokhorov, Jacco Vink +97
RCW 86 is a supernova remnant whose origin has recently been linked to an off-center explosion within a cavity created by its progenitor star. In the southwestern region, the forwa…
Super-Eddington Accretion Geometry: a Remarkable Stability of the Hidden Ultraluminous X-Ray Source Cygnus X-3
Romana Mikušincová, Alexandra Veledina, Fabio Muleri +112
We report on the average and orbital phase-resolved polarization of Cyg X-3 in the hard state during the 2023 Imaging X-ray Polarimetry Explorer (IXPE) observational campaign. We f…
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…
X-ray Polarization Detection of the Pulsar Wind Nebula in G21.5-0.9 with IXPE
Niccolò Di Lalla, Nicola Omodei, Niccolò Bucciantini +98
We present the X-ray polarization observation of G21.5-0.9, a young Galactic supernova remnant (SNR), conducted with the Imaging X-ray Polarimetry Explorer (IXPE) in October 2023,…
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…
High optical to X-ray polarization ratio reveals Compton scattering in BL Lacertae's jet
Ivan Agudo, Ioannis Liodakis, Jorge Otero-Santos +147
Blazars, supermassive black hole systems (SMBHs) with highly relativistic jets aligned with the line of sight, are the most powerful long-lived emitters of electromagnetic emission…
X-ray Polarization of the High-Synchrotron-Peak BL Lacertae Object 1ES 1959+650 during Intermediate and High X-ray Flux States
Luigi Pacciani, Dawoon E. Kim, Riccardo Middei +97
We report the Imaging X-ray Polarimetry Explorer (IXPE) polarimetric and simultaneous multiwavelength observations of the high-energy-peaked BL Lacertae (HBL) object 1ES 1959+650,…
XMM/HST monitoring of the ultra-soft highly accreting Narrow Line Seyfert 1 RBS 1332
R. Middei, S. Barnier, F. G. Saturni +10
Ultra-soft narrow line Seyfert 1 (US-NLSy) are a poorly observed class of active galactic nuclei characterized by significant flux changes and an extreme soft X-ray excess. This pe…
Periodic Gamma-ray Modulation of the blazar PG 1553+113 Confirmed by Fermi-LAT and Multi-wavelength Observations
S. Abdollahi, L. Baldini, G. Barbiellini +98
A 2.1-year periodic oscillation of the gamma-ray flux from the blazar PG 1553+113 has previously been tentatively identified in almost 7 year of data from the Fermi Large Area Tele…
Characterization of Markarian 421 during its most violent year: Multiwavelength variability and correlations
K. Abe, S. Abe, J. Abhir +212
Mrk 421 was in its most active state around early 2010, which led to the highest TeV gamma-ray flux ever recorded from any active galactic nuclei. We aim to characterize the multiw…
IXPE Observation of the Low-Synchrotron Peaked Blazar S4 0954+65 During An Optical-X-ray Flare
Pouya M. Kouch, Ioannis Liodakis, Francesco Fenu +134
The X-ray polarization observations made possible with the Imaging X-ray Polarimetry Explorer (IXPE) offer new ways of probing high-energy emission processes in astrophysical jets…
Evidence for a shock-compressed magnetic field in the northwestern rim of Vela Jr. from X-ray polarimetry
Dmitry A. Prokhorov, Yi-Jung Yang, Riccardo Ferrazzoli +97
Synchrotron X-ray emission has been detected from nearly a dozen young supernova remnants (SNRs). X-rays of synchrotron origin exhibit linear polarization in a regular, non-randoml…
A Two-Week Monitoring Campaign on Mrk 421
W. Peter Maksym, Ioannis Liodakis, M. Lynne Saade +153
X-ray polarization is a unique new probe of the particle acceleration in astrophysical jets made possible through the Imaging X-ray Polarimetry Explorer. Here we report on the firs…
Insights from the first flaring activity of a high-synchrotron-peaked blazar with X-ray polarization and VHE gamma rays
MAGIC Collaboration, K. Abe, S. Abe +250
We study a flaring activity of the HSP Mrk421 that was characterized from radio to very-high-energy (VHE; E TeV) gamma rays with MAGIC, Fermi-LAT, Swift, XMM-Newton and sever…
The HERMES (High Energy Rapid Modular Ensemble of Satellites) Pathfinder mission
Y. Evangelista, F. Fiore, R. Campana +68
HERMES (High Energy Rapid Modular Ensemble of Satellites) Pathfinder is a space-borne mission based on a constellation of six nano-satellites flying in a low-Earth orbit (LEO). The…
Analysis of Crab X-ray Polarization using Deeper IXPE Observations
Josephine Wong, Tsunefumi Mizuno, Niccoló Bucciantini +98
We present Crab X-ray polarization measurements using IXPE data with a total exposure of 300ks, three times more than the initial 2022 discovery paper. Polarization is detected in…
X-ray and multiwavelength polarization of Mrk 501 from 2022 to 2023
Chien-Ting J. Chen, Ioannis Liodakis, Riccardo Middei +143
We present multiwavelength polarization measurements of the luminous blazar Mrk~501 over a 14-month period. The 2--8 keV X-ray polarization was measured with the Imaging X-ray Pola…
A Swift X-ray view of the SMS4 sample -- II: X-ray properties of 17 bright radio sources
Alessandro Maselli, William R. Forman, Christine Jones +2
Based on a proposal to observe 18 bright radio sources from the SMS4 catalog with the Neil Gehrels Swift Observatory (hereafter Swift), we obtained X-ray observations of 17 targets…
An IXPE-Led X-ray Spectro-Polarimetric Campaign on the Soft State of Cygnus X-1: X-ray Polarimetric Evidence for Strong Gravitational Lensing
James F. Steiner, Edward Nathan, Kun Hu +134
We present the first X-ray spectropolarimetric results for Cygnus X-1 in its soft state from a campaign of five IXPE observations conducted during 2023 May-June. Companion multiwav…