86 citations · 814 across the 38 of their papers we have counts for
41 papers
HALO II: Constraining Hubble constant through continuum delay fitting of Fairall 9
Amit Kumar Mandal, Francisco Pozo Nuñez, Vikram Kumar Jaiswal +28
The Hubble tension remains one of the most significant unresolved problems in modern cosmology. A key question is whether it may arise from underestimated systematic uncertainties…
Consistency between X-ray and UV-Optical reverberation measurements in NGC 5548
Amit Kumar Mandal, Bożena Czerny, Michal Dovčiak +2
The hard X-rayemitting hot corona is a key component of active galaxies. Constraints on the hot corona height can be derived from reverberation studies in both the X-ray and opt…
Disk reflection as the origin of the X-ray polarization of NGC 4151 with IXPE
E. Kammoun, M. Dovčiak, J. Podgorný +6
We present an X-ray spectro-polarimetric study of the nearby type-1 active galactic nucleus NGC 4151 using two long IXPE observations obtained in 2022 and 2024, supported by simult…
HALO I: Photometric continuum reverberation mapping of Fairall 9
Amit Kumar Mandal, Francisco Pozo Nuñez, Vikram Kumar Jaiswal +23
We investigate the origin of inter-band continuum time delays in active galactic nuclei (AGNs) to study the structure and properties of their accretion disks. We aim to measure the…
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…
Exploring MAXI J1744-294: IXPE insights into a Newly Discovered X-ray Transient
Lorenzo Marra, Romana Mikušincová, Federico M. Vincentelli +33
We present the first IXPE spectro-polarimetric observation of the black hole candidate MAXI J1744294, a transient X-ray source discovered during a bright 2025 outburst in the Ga…
Variability of X-ray polarization of Cyg X-1
Vadim Kravtsov, Anastasiia Bocharova, Alexandra Veledina +31
We present the results of a three-year X-ray, optical, and radio polarimetric monitoring campaign of the prototypical black hole X-ray binary Cyg X-1, conducted from 2022 to 2024.…
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,…
Explaining the UV to X-ray correlation in AGN within the framework of X-ray illumination of accretion discs
E. Kammoun, I. E. Papadakis, M. Dovčiak +3
It is established that the ultraviolet (UV) and X-ray emissions in active galactic nuclei (AGN) are tightly correlated. This correlation is observed both in low- and high-redshift…
Frequency-resolved time lags due to X-ray disk reprocessing in AGN
Christos Panagiotou, Iossif Papadakis, Erin Kara +6
Over the last years, a number of broadband reverberation mapping campaigns have been conducted to explore the short-term UV and optical variability of nearby AGN. Despite the exten…
X-ray reverberation modelling of the continuum, optical/UV time-lags in quasars
D. A. Langis, I. E. Papadakis, E. Kammoun +2
Context: Extensive, multi-wavelength monitoring campaigns of nearby and higher redshift active galactic nuclei (AGN) have shown that the UV/optical variations are well correlated w…
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…
Investigating the consistency of the shape and flux of X-ray reflection spectra in the hard state with an accretion disk reaching close to the black hole
Sudeb Ranjan Datta, Michal Dovčiak, Michal Bursa +3
The observed spectra from black hole (BH) X-ray binaries (XRBs) typically consist of two primary components: multitemperature blackbody (BB) originating from the accretion disk in…
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…
X-ray reverberation as an explanation for UV/optical variability in nearby Seyferts
M. Papoutsis, I. E. Papadakis, C. Panagiotou +2
Active galactic nuclei (AGNs) are known to be variable across all wavelengths. Significant observational efforts have been invested in the last decade in studying their ultraviolet…
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…
IXPE observation of PKS 2155-304 reveals the most highly polarized blazar
Pouya M. Kouch, Ioannis Liodakis, Riccardo Middei +133
We report the X-ray polarization properties of the high-synchrotron-peaked (HSP) blazar PKS 2155304 based on observations with the Imaging X-ray Polarimetry Explorer (IXPE). We…
Recovery of the X-ray polarisation of Swift J1727.81613 after the soft-to-hard spectral transition
J. Podgorný, J. Svoboda, M. Dovčiak +34
We report on the detection of X-ray polarisation in the black-hole X-ray binary Swift J1727.81613 during its dim hard spectral state by the Imaging X-ray Polarimetry Explorer (I…
Pulsar-wind-nebula-powered Galactic center X-ray filament G0.13-0.11: Proof of the synchrotron nature by IXPE
Eugene Churazov, Ildar Khabibullin, Thibault Barnouin +103
We report the discovery of X-ray polarization from the X-ray-bright filament. G0.13-0.11 in the Galactic center (GC) region. This filament features a bright, hard X-ray source that…
X-ray Polarization Reveals the Precessions of the Neutron Star in Hercules X-1
Jeremy Heyl, Victor Doroshenko, Denis González-Caniulef +100
In an accreting X-ray pulsar, a neutron star accretes matter from a stellar companion through an accretion disk. The high magnetic field of the rotating neutron star disrupts the i…
X-ray polarization from parsec-scale components of active galactic nuclei: observational prospects
J. Podgorný, F. Marin, M. Dovčiak
We present a broad analysis of X-ray polarimetric observational prospects for radio-quiet active galactic nuclei (AGN), focusing on the role of parsec-scale components. We provide…
Magnetic Field Properties inside the Jet of Mrk 421: Multiwavelength Polarimetry Including the Imaging X-ray Polarimetry Explorer
Dawoon E. Kim, Laura Di Gesu, Ioannis Liodakis +133
We conducted a polarimetry campaign from radio to X-ray wavelengths of the high-synchrotron-peak (HSP) blazar Mrk 421, including Imaging X-ray Polarimetry Explorer (IXPE) measureme…
X-ray Polarization of the BL Lac Type Blazar 1ES 0229+200
Steven R. Ehlert, Ioannis Liodakis, Riccardo Middei +110
We present polarization measurements in the band from blazar 1ES 0229+200, the first extreme high synchrotron peaked source to be observed by the Imag…