I. Myserlis
A5037862729- Astrophysics and Cosmic Phenomena
- Radio Astronomy Observations and Technology
- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Particle Accelerators and Free-Electron Lasers
- Neutrino Physics Research
- Dark Matter and Cosmic Phenomena
- Astronomical Observations and Instrumentation
- Gyrotron and Vacuum Electronics Research
- Pulsars and Gravitational Waves Research
- Solar and Space Plasma Dynamics
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Galaxies: Formation, Evolution, Phenomena
- Ionosphere and magnetosphere dynamics
- Computational Physics and Python Applications
- Particle accelerators and beam dynamics
- Geophysics and Gravity Measurements
- Particle Detector Development and Performance
- Calibration and Measurement Techniques
- Particle physics theoretical and experimental studies
- Radiation Detection and Scintillator Technologies
- GNSS positioning and interference
- Astro and Planetary Science
- Astrophysics and Star Formation Studies
Instituto de Radioastronomía Milimétrica
2021-2025
Max Planck Institute for Radio Astronomy
2015-2024
The University of Texas at San Antonio
2024
Institut de Radioastronomie Millimétrique
2023
Shanghai Jiao Tong University
2023
Max Planck Society
2013-2020
California Institute of Technology
2018
University of Crete
2013-2018
Goddard Space Flight Center
2018
University of Maryland, College Park
2018
Abstract Most of the light from blazars, active galactic nuclei with jets magnetized plasma that point nearly along line sight, is produced by high-energy particles, up to around 1 TeV. Although are known be ultimately powered a supermassive black hole, how particles accelerated such high energies has been an unanswered question. The process must related magnetic field, which can probed observations polarization jets. Measurements radio optical polarization—the only range available until...
We present first results on polarization swings in optical emission of blazars obtained by RoboPol, a monitoring program an unbiased sample gamma-ray bright specially designed for effective detection such events. A possible connection swing events with periods high activity gamma rays is investigated using the dataset during season operation. It was found that brightest flares tend to be located closer time rotation events, which may indication two separate mechanisms responsible rotations....
We present average R-band optopolarimetric data, as well variability parameters, from the first and second RoboPol observing season. investigate whether gamma-ray-loud gamma-ray-quiet blazars exhibit systematic differences in their optical polarization properties. find that have a systematically higher fraction (0.092) than (0.031), with hypothesis of two samples being drawn same distribution fractions rejected at 3σ level. not found any evidence this discrepancy is related to redshift...
Abstract Particle acceleration mechanisms in supermassive black hole jets, such as shock acceleration, magnetic reconnection, and turbulence, are expected to have observable signatures the multiwavelength polarization properties of blazars. The recent launch Imaging X-Ray Polarimetry Explorer (IXPE) enables us, for first time, use X-ray band (2–8 keV) probe jet synchrotron emission high-synchrotron-peaked BL Lac objects (HSPs). We report discovery linear (degree Π x = 15% ± 2% electric...
Abstract The lower-energy peak of the spectral energy distribution blazars has commonly been ascribed to synchrotron radiation from relativistic particles in jets. Despite consensus regarding jet emission processes, particle acceleration mechanism is still debated. Here, we present first X-ray polarization observations PG 1553+113, a high-synchrotron-peak blazar observed by Imaging Polarimetry Explorer (IXPE). We detect an degree (10 ± 2)% along electric-vector position angle ψ X = 86° 8°....
Abstract We report the first >99% confidence detection of X-ray polarization in BL Lacertae. During a recent X-ray/ γ -ray outburst, 287 ks observation (2022 November 27–30) was taken using Imaging Polarimetry Explorer (IXPE), together with contemporaneous multiwavelength observations from Neil Gehrels Swift observatory and XMM-Newton soft X-rays (0.3–10 keV), NuSTAR hard (3–70 optical Calar Alto Perkins Telescope observatories. Our data suggest that IXPE energy band is at crossover...
Abstract Observations of linear polarization in the 2–8 keV energy range with Imaging X-ray Polarimetry Explorer (IXPE) explore magnetic field geometry and dynamics regions generating nonthermal radiation relativistic jets blazars. These jets, particularly blazars whose spectral distribution peaks at energies, emit X-rays via synchrotron from high-energy particles within jet. IXPE observations X-ray-selected BL Lac–type blazar 1ES 1959+650 on 2022 May 3–4 showed a significant degree Π x =...
3C84 is a nearby radio source with complex total intensity structure, showing linear polarisation and spectral patterns. A detailed investigation of the central engine region necessitates use VLBI above hitherto available maximum frequency 86GHz. Using ultrahigh resolution observations at highest 228GHz, we aim to directly detect compact structures understand physical conditions in 3C84. We used EHT 228GHz and, given limited (u,v)-coverage, applied geometric model fitting data. also employed...
The X-ray polarization observations, made possible with the Imaging Polarimetry Explorer (IXPE), offer new ways of probing high-energy emission processes in astrophysical jets from blazars. Here, we report first observation blazar S4 0954+65 a high optical and state. During our multi-wavelength (MWL) campaign source, detected an flare whose peak coincided flare. This optical-X-ray most likely took place feature moving along parsec-scale jet, imaged at 43 GHz by Very Long Baseline Array...
We present measurements of rotations the optical polarization blazars during second year operation RoboPol, a monitoring programme an unbiased sample gamma-ray bright specially designed for effective detection such events, and we analyse large set rotation events discovered in two years observation. investigate patterns variability parameters total flux density compare them to behaviour non-rotating state. have searched possible correlations between average polarization-plane polarization,...
We use results of our 3 yr polarimetric monitoring programme to investigate the previously suggested connection between rotations polarization plane in optical emission blazars and their gamma-ray flares GeV band. The homogeneous set 40 rotation events 24 sources detected by RoboPol is analysed together with data provided Fermi-LAT. confirm that are indeed related closest time lags these consistent zero. Amplitudes anticorrelated amplitudes flares. This presumably caused higher relativistic...
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 source, quantify its characteristics. relied on most systematic monitoring of such system in cm mm bands which conducted with Effelsberg 100 m IRAM 30 telescopes covers longest time-baselines frequencies date. extract variability parameters compute brightness temperatures Doppler factors. powers were computed light curves...
Recent population studies have shown that the variability Doppler factors can adequately describe blazars as a population. We use flux density variations found within extensive radio multi-wavelength datasets of F-GAMMA program, total 10 frequencies from 2.64 up to 142.33 GHz, in order estimate for 58 $γ$-ray bright sources, 20 which no factor has been estimated before. employ specifically designed algorithms obtain model each flare at frequency. then identify event and track its evolution...
Context. The γ-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 apparent (≈100°) position-angle change in projection on the sky plane.
Context. We investigate the optical polarization properties of high-energy BL Lac objects using data from RoboPol blazar monitoring program and Nordic Optical Telescope.
Abstract We present the first polarimetric space very long baseline interferometry (VLBI) observations of OJ 287, observed with RadioAstron at 22 GHz during a perigee session on 2014 April 4 and five near-in-time snapshots, together contemporaneous ground VLBI 15, 43, 86 GHz. Ground-space fringes were obtained up to projected 3.9 Earth diameters session, record 15.1 snapshot sessions, allowing us image innermost jet an angular resolution ∼50 μ as, highest ever achieved for 287. Comparison...
Aims. We aim to probe the magnetic field geometry and particle acceleration mechanism in relativistic jets of supermassive black holes. Methods. conducted a polarimetry campaign from radio X-ray wavelengths high-synchrotron-peak (HSP) blazar Mrk 421, including Imaging Polarimetry Explorer (IXPE) measurements 2022 December 6–8. During IXPE observation, we also monitored 421 using Swift -XRT obtained single observation with XMM-Newton improve spectral analysis. The time-averaged polarization...
Abstract We present polarization measurements in the 2–8 keV band from blazar 1ES 0229+200, first extreme high synchrotron peaked source to be observed by Imaging X-ray Polarimetry Explorer (IXPE). Combining two exposures separated about weeks, we find degree of Π X = 17.9% ± 2.8% at an electric-vector position angle ψ 25.°0 4.°6 using a spectro-polarimetric fit joint IXPE and XMM-Newton observations. There is no evidence for or varying significantly with energy time on both short timescales...
We report the X-ray polarization properties of high-synchrotron-peaked (HSP) blazar PKS 2155−304 based on observations with Imaging Polarimetry Explorer (IXPE). observed source between Oct 27 and Nov 7, 2023. also conducted an extensive contemporaneous multiwavelength (MW) campaign. find that during first half ( T 1 ) IXPE pointing, exhibited highest degree detected for HSP thus far, (30.7 ± 2.0)%; this dropped to (15.3 2.1)% second 2 ). The angle remained stable pointing at 129.4° ±1.8°...
We present first results from RoboPol, a novel-design optical polarimeter operating at the Skinakas Observatory in Crete. The data, taken during May - June 2013 commissioning of instrument, constitute single-epoch linear polarization survey sample gamma-ray loud blazars, defined according to unbiased and objective selection criteria, easily reproducible simulations, as well comparison of, otherwise similar, quiet blazars. As such, this are appropriate for both phenomenological population...
We describe the data reduction pipeline and control system for RoboPol project. The project is monitoring optical R-band magnitude linear polarization of a large sample active galactic nuclei that dominated by blazars. calibrates reduces each exposure frame, producing measurement every source in 13 arcmin × field view. combines dynamic scheduler, real-time reduction, telescope automation to allow high-efficiency unassisted observations.
To fully exploit the scientific potential of Fermi mission, we initiated F-GAMMA program. Between 2007 and 2015 it was prime provider complementary multi-frequency monitoring in radio regime. We quantify variability gamma-ray blazars. investigate its dependence on source class examine whether is related to loudness. Finally, assess validity a putative correlation between two bands. The monitored monthly sample about 60 sources at up twelve frequencies 2.64 228.39 GHz. perform time series...
We present a new set of optical polarization plane rotations in blazars, observed during the third year operation RoboPol. The entire rotation events discovered three years observations is analysed with aim determining whether these are inherent all blazars. It found that frequency varies widely among This variation cannot be explained either by difference relativistic boosting or selection effects caused average fractional polarization. conclude characteristic subset blazars and they occur...
ABSTRACT We present the design and performance of RoboPol, a four-channel optical polarimeter operating at Skinakas Observatory in Crete, Greece. RoboPol is capable measuring both relative linear Stokes parameters q u (and total intensity I) one sky exposure. Though primarily used to measure polarization point sources R band, instrument features additional filters (B, V, I), enabling multiwavelength imaging polarimetry over large field view (13.6′ × 13.6′). demonstrate accuracy stability...