A5022310339- Astrophysics and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Particle Accelerators and Free-Electron Lasers
- Radio Astronomy Observations and Technology
- Particle Detector Development and Performance
- Dark Matter and Cosmic Phenomena
- Astronomical Observations and Instrumentation
- Solar and Space Plasma Dynamics
- Particle physics theoretical and experimental studies
- Advanced X-ray Imaging Techniques
- X-ray Spectroscopy and Fluorescence Analysis
- Calibration and Measurement Techniques
- Gyrotron and Vacuum Electronics Research
- Neutrino Physics Research
- Stellar, planetary, and galactic studies
- Magnetic confinement fusion research
- Laser-Plasma Interactions and Diagnostics
- Particle accelerators and beam dynamics
- Medical Imaging Techniques and Applications
- Nuclear Physics and Applications
- Astronomy and Astrophysical Research
- Melanoma and MAPK Pathways
- Advancements in Photolithography Techniques
- Superconducting Materials and Applications
Abastumani Astrophysical Observatory
2013-2023
Ilia State University
2013-2023
Brera Astronomical Observatory
2017-2023
University of Michigan–Ann Arbor
2016-2018
Istituto di Astrofisica Spaziale e Fisica cosmica di Palermo
2014-2017
BL Lacertae has been the target of four observing campaigns by Whole Earth Blazar Telescope (WEBT) collaboration. In this paper we present $UBVRI$ light curves obtained WEBT from 1994 to 2002, including last, extended Lac 2001 campaign. A total about 7500 optical observations performed 31 telescopes Japan Mexico have collected, be added $\sim 15600$ Campaign 2000. All these data allow one follow source emission behaviour with unprecedented detail. The analysis colour indices reveals that...
The quasar 3C 279 was the target of an extensive multiwavelength monitoring campaign from 2006 January through April. An optical-IR-radio by Whole Earth Blazar Telescope (WEBT) collaboration organized around target-of-opportunity X-ray and soft γ-ray observations with Chandra INTEGRAL in mid-January, additional coverage RXTE Swift XRT. In this paper we focus on results WEBT campaign. source exhibited substantial variability optical flux spectral shape, a characteristic timescale few days....
Aims.A huge multiwavelength campaign targeting the blazar AO 0235+164 was organized by Whole Earth Blazar Telescope (WEBT) in 2003–2005 to study variability properties of source.
ABSTRACT We present the results of Swift and NuSTAR observations nearby BL Lac object Mrk 421 during 2013 January–June. The source exhibited a strong long-term variability in 0.3–10 keV 3–79 bands with maximum-to-minimum daily-binned flux ratios 22 95, respectively, about 3 months, mainly due to unprecedented X-ray outbursts by more than an order magnitude both within 2 weeks April when count rate exceeded level 200 cts s −1 for first time, became one brightest sources sky. was also very...
We present the results of our monitoring high-energy peaked BL Lac object PKS 2155−304 by Swift/X-Ray Telescope (XRT) during 2005–2012. Our timing study shows that source was highly variable both on longer (weeks-to-months) and intra-day time-scales, up to a factor 7 in flux, 30 per cent fractional variability amplitudes, with no periodic variations. The X-ray spectra are mainly curved broad ranges photon index, curvature parameter, hardness ratio which exhibit significant flux different...
We present the results based on monitoring of high-energy peaked BL Lacertae object 1ES 1959+650 by Swift satellite during 2005–2014. Our timing study shows that source was highly variable longer (weeks-to-months) time-scales with 0.3–10 keV fluxes ranging a factor 8. It sometimes showed significant intra-day variability in course ∼1 ks, detected mainly epochs higher brightness states. The flux exhibited an erratic character and no signatures periodic variations are revealed. X-ray spectra...
Abstract We present an X-ray flaring activity of 1ES 1959+650 in 2015 August–2016 January, which was the most powerful and prolonged during 10.75 yr period since start its monitoring with Telescope onboard Swift. A new highest historical 0.3–10 keV count rate recorded three times that makes this object third BL Lacertae source exceeding level 20 counts s−1. Along overall variability by a factor 5.7, epoch characterized fast flares 2.0–3.1, accompanied extreme spectral variability. The also...
We present the results from timing and spectral study of Mrk\,421 based mainly on \emph{Swift} data in X-ray energy range obtained during time interval 2015\,December--2018\,April. The most extreme flaring activity long-term, daily intraday timescales was observed 2-month period which started 2017\,December when 0.3--10\,keV flux exceeded a level 5$\times$10$^{-9}$erg\,cm$^{-2}$s$^{-1}$, recorded only twice previously. While TeV-band variabilities mostly were correlated, source often varied...
The X-ray variability of the BL Lacertae source Mrk 501 was studied during 11.5 yr monitoring with Swift. Here, we report results this study pertaining to epoch 2014 March–October, when our target showed most powerful and long-lasting flaring activity. This characterized by flares varying in amplitude factors 2–5 on time-scales a few weeks or shorter. We detected 35 instances intraday variability, sometimes occurring within 1 ks observational runs. flux generally correlated TeV flux, while...
Abstract We present the results of Swift observations nearby BL Lac object Mrk 421 during 2013 November–2015 June. The source exhibited a strong long-term variability in 0.3–10 keV band, with maximum-to-minimum flux ratio 13, and underwent X-ray flares by factor 1.8–5.2 on timescales few weeks or shorter. showed 48 instances intraday this period, which sometimes was observed within 1 ks observational run. It characterized fractional amplitudes 1.5(0.3)%–38.6(0.4)% doubling/halving times...
Abstract We present detailed results of Swift observations the nearby TeV-detected blazar Mrk 421, based on rich archival data obtained during 2005 March–2008 June. The best fits 0.3–10 keV spectra were mainly using log-parabolic model, yielding low spectral curvatures expected in case efficient stochastic acceleration particles. During strong X-ray flares, position synchrotron energy distribution peak <?CDATA ${E}_{{\rm{p}}}$?> was beyond 8 for 41 spectra, while it sometimes situated at UV...
Abstract We present the results from a detailed spectral and timing study of Mrk 421 based on rich archival Swift data obtained during 2009–2012. Best fits 0.3–10 keV spectra were mostly using log-parabolic model showing relatively low curvature that is expected in case efficient stochastic acceleration particles. The position synchrotron energy density peak E p 173 found at energies higher than 2 keV. photon index 1 exhibited very broad range values = 1.51–3.02, hard with < 1.7 observed...
We present the detailed timing and spectral results obtained during Swift observations of TeV-detected blazar 1ES 1959+650 in 2016 August–2017 November. The source continued its trend gradually enhancing X-ray flaring activity 0.3–10 keV energy range, starting 2015 August, a new highest historical brightness state was recorded twice. A long-term high superimposed by both weak strong flares, we detected 32 instances intraday flux variability, including several occasions extremely fast...
This paper presents a catalog of 312 X-ray selected BL Lacerate objects (XBLs), optically identified through the end 2011. It contains names from different surveys, equatorial coordinates, redshifts, multifrequency flux values, and luminosities for each source. In addition, characteristics XBLs are statistically investigated (redshift, radio/optical/X-ray luminosities, central black hole (BH) mass, synchrotron peak frequency, broadband spectral indices, optical variability). Their values...
Abstract We present the spectral and timing results obtained during intense observations of Mrk 421 by Swift-based ultraviolet to X-ray instruments 2018 April–2023 December. The source showed various strengths flaring activity, exceeding a level 3.5 × 10 −9 erg cm −2 s −1 strongest 0.3–10 keV flares. Our study identifies number intraday brightness variability, including 61 instances that occurred within 1 ks exposures are consistent with shock-in-jet scenario accompanied significant, fast...
Abstract This paper presents the results of a detailed X-ray timing and spectral analysis Mrk 501, which are based mainly on Swift data obtained during 2021 February–2022 December. The source showed strongly enhanced activity, characterized by long-term increase in baseline 0.3–10 keV flux level superimposed shorter-term flares timescales few weeks to about 2 months. During some time intervals, 501 was brightest blazar sky and, moreover, an intense intraday variability, sometimes detected...
Context. The multi-wavelength (MWL) properties of some TeV-detected blazars are still poorly understood. By studying the MWL BL Lacertae source 1ES 0033+595, we make further progress in our understanding instable physical processes responsible for particle acceleration to ultra-relativitic energies and observed emission properties. Aims. This paper presents results a detailed X-ray timing spectral analysis allowing us draw conclusions about mechanisms generation emission. We also examined...