A5039190362- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Radio Astronomy Observations and Technology
- Dark Matter and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Neutrino Physics Research
- Particle Detector Development and Performance
- Particle Accelerators and Free-Electron Lasers
- Pulsars and Gravitational Waves Research
- Astronomical Observations and Instrumentation
- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Particle physics theoretical and experimental studies
- Gyrotron and Vacuum Electronics Research
- Cosmology and Gravitation Theories
- SAS software applications and methods
- Stellar, planetary, and galactic studies
- Computational Physics and Python Applications
- Solar and Space Plasma Dynamics
- Nuclear Physics and Applications
- Astro and Planetary Science
- Noncommutative and Quantum Gravity Theories
- Advanced X-ray and CT Imaging
- Precipitation Measurement and Analysis
- Terahertz technology and applications
International Center for Relativistic Astrophysics Network
2016-2025
International Center for Relativistic Astrophysics
2014-2024
Sapienza University of Rome
2011-2024
Armenian National Agrarian University
2024
Instituto de Astrofísica de Canarias
2021-2024
Universidad de La Laguna
2021-2024
Agrobiotechnology Institute
2024
Max Planck Institute for Physics
2021-2023
National Academy of Sciences of Armenia
2012-2023
Universitat de Barcelona
2021-2023
We present the dissection in space, time, and energy of region around IceCube-170922A neutrino alert. This study is motivated by: (1) first association between a alert blazar flaring state, TXS 0506+056; (2) evidence activity during 2014 - 2015 from same direction; (3) lack an accompanying simultaneous $\gamma$-ray enhancement counterpart; (4) contrasting neighbouring bright source, PKS 0502+049, 2015. Our makes use multi-wavelength archival data accessed through Open Universe tools includes...
ABSTRACT The blazar PKS 0735+178 is possibly associated with multiple neutrino events observed by the IceCube, Baikal, Baksan, and KM3NeT telescopes while it was flaring in γ-ray, X-ray, ultraviolet, optical bands. We present a detailed study of this peculiar to investigate temporal spectral changes multiwavelength emission when were observed. analysis Swift-XRT snapshots reveal flux variability more than factor 2 about 5 × 103 s during observation on 2021 December 17. In γ-ray band, source...
Context. The detection of quasi-periodic oscillations (QPOs) in the light curves active galactic nuclei (AGNs) can provide insights into physics super-massive black holes (SMBHs) powering these systems and could represent a signature existence SMBH binaries, setting fundamental constraints on evolution Universe. Aims. identification long-term QPOs, characterized by periods order several months to years, is particularly challenging only be achieved via all-sky monitoring instruments that...
Abstract The observation of the IceCube-170922A event from direction TXS 0506+056 when it was in its enhanced γ -ray emission state offers a unique opportunity to investigate lepto-hadronic processes blazar jets. Here, observed broadband is explained by boosted synchrotron/synchrotron self Compton jet, whereas data during neutrino inelastic interactions jet-accelerated protons dense gaseous target. proton energy distribution <?CDATA $\sim {E}_{p}^{-2.50}$?> , calculated straightforwardly...
Most empirical research on the subject of corruption has found evidence its deleterious effects firms, industries, and society in general. Yet persistence corruption, which is present virtually every form public governance, suggests that disparate benefits are difficult to unravel lead support for status quo. In this paper, authors analyze survey data from over 400 Armenian businesses study perceived favorability impact firm-level performance. The relies two ordered response questions were...
We propose that the "inner engine" of a type I binary-driven hypernova (BdHN) is composed Kerr black hole (BH) in non-stationary state, embedded uniform magnetic field $B_0$ aligned with BH rotation axis, and surrounded by an ionized plasma extremely low density $10^{-14}$~g~cm$^{-3}$. Using GRB 130427A as prototype we show this acts sequence "elementary impulses". Electrons are accelerated to ultra-relativistic energy near horizon and, propagating along polar $\theta =0$, they can reach...
Blazars research is one of the hot topics contemporary extra-galactic astrophysics. That because these sources are most abundant type gamma-ray and suspected to play a central role in multi-messenger We have used swift_xrtproc, tool carry out an accurate spectral photometric analysis Swift-XRT data all blazars observed by Swift at least 50 times between December 2004 end 2020. present database X-ray spectra, best-fit parameter values, count-rates flux estimations several energy bands over...
Aims. Open Universe for Blazars is a set of high-transparency multi-frequency data products blazar science, and the tools designed to generate them. are drawing growing interest following consolidation their position as most abundant type source in extragalactic very high-energy γ -ray sky, because status prime candidate sources nascent field multi-messenger astrophysics. As such, astrophysics becoming increasingly driven, depending on integration combined analysis large quantities from...
ABSTRACT The observation of a very high-energy neutrino by IceCube (IceCube-170922A) and its association with the flaring blazar TXS 0506 + 056 provided first multimessenger observations jets, demonstrating important role protons in their dynamics emission. In this paper, we present SOPRANO (https://www.amsdc.am/soprano), new conservative implicit kinetic code that follows time evolution isotropic distribution functions protons, neutrons, secondaries produced photo-pion photo-pair...
We present the results of an extensive analysis optical, ultraviolet, X-ray and $\gamma$-ray data collected from observations BL Lac objects prototype Lacertae carried out over a period nearly 13 years, between August 2008 March 2021. The source is characterized by strongly variable emission at all frequencies, often accompanied spectral changes. In band several prominent flares have been detected, largest one reaching flux $F_{\rm \gamma}(>196.7\: {\rm MeV})=(4.39\pm1.01)\times10^{-6}\:{\rm...
Abstract Observations of supernovae (SNe) Ic occurring after the prompt emission long gamma-ray bursts (GRBs) are addressed within binary-driven hypernova (BdHN) model where GRBs originate from a binary composed ∼10 M ⊙ carbon–oxygen (CO) star and neutron (NS). The CO core collapse gives trigger, leading to with fast-spinning newborn NS ( ν NS) at its center. evolution depends strongly on period, P bin . For ∼ 5 min, BdHNe I occur energies 10 52 –10 54 erg. accretion SN ejecta onto leads...
Abstract Modeling the multiwavelength spectral energy distributions (SEDs) of blazars provides key insights into underlying physical processes responsible for emission. While SED modeling with self-consistent models is computationally demanding, it essential a comprehensive understanding these astrophysical objects. We introduce novel, efficient method SEDs by mean convolutional neural network (CNN). In this paper, we trained CNN on leptonic model that incorporates synchrotron and inverse...
We report on an analysis of Fermi Large Area Telescope data from four years observations the nearby radio galaxy Centaurus A (Cen A). The increased photon statistics results in a detection high-energy (>100 MeV) gamma-rays up to 50 GeV core Cen A, with significance about 44σ. average gamma-ray spectrum reveals evidence for possible deviation simple power law. likelihood broken power-law model shows that index becomes harder above Eb ≃ 4 GeV, changing Γ1 = 2.74 ± 0.03 below Γ2 2.09 0.20...
We report on broadband observations of CTA 102 ($z=1.037$) during the active states in 2016-2017. In $\gamma$-ray band, Fermi LAT observed several prominent flares which followed a harder-when-brighter behavior: hardest photon index $\Gamma=1.61\pm 0.10$ being unusual for FSRQs. The peak flux above 100 MeV $(3.55\pm0.55)\times10^{-5}\:{\rm photon\:cm^{-2}\:s^{-1}}$ MJD 57738.47 within 4.31 minutes, corresponds to an isotropic luminosity $L_{\gamma}=3.25\times10^{50}\:{\rm erg\:s^{-1}}$,...
We report on a detailed investigation of the $γ$-ray emission from 26 non-blazar AGNs based Fermi LAT data accumulated for 7 years. The photon index changes in range 1.84-2.86 and flux varies few times $10^{-9} photon\: cm^{-2} s^{-1}$ to $10^{-7} cm^{-2}s^{-1}$. Over long time periods, power-law provides an adequate description spectra almost all sources. Significant curvature is observed NGC 1275, 6251, SBS 0846+513 PMN J0948+0022 their are better described by log-parabola or with...
Blazars are a peculiar class of active galactic nuclei (AGNs) that enlighten the sky at all wavelengths. The electromagnetic emission these sources is jet-dominated resulting in spectral energy distribution (SED) has typical double-humped shape. X-ray photons provide wealth information on physics each source as band we can observe tail SED first peak, rise second one or transition between two. NuSTAR, thanks to its capability focusing X-rays up 79 keV provides broadband data particularly...
High-redshift blazars are among the most powerful objects in Universe. The spectral and temporal properties of thirty-three distant ($z>2.5$) detected high energy $\gamma$-ray band investigated by analyzing {\it Fermi}-LAT Swift} UVOT/ XRT data. considered sources have soft time averaged spectra ($\Gamma_{\rm \gamma}\geq2.2$) whereas those that been observed X-ray hard X}=1.01-1.86$). flux high-redshift ranges from $4.84\times10^{-10}$ to $1.50\times10^{-7}\:{\rm photon\:cm^{-2}\:s^{-1}}$...
ABSTRACT We recall evidence that long gamma-ray bursts (GRBs) have binary progenitors and give new examples. Binary-driven hypernovae (BdHNe) consist of a carbon–oxygen core (COcore) neutron star (NS) companion. For periods ∼5 min, the COcore collapse originates subclass BdHN I characterized by (1) an outstanding supernova (SN; ‘SN-rise’); (2) black hole (BH), born from NS SN matter accretion, leading to GeV emission with luminosity $L_{\rm GeV} = A_{\rm GeV}\, t^{-\alpha _{\rm GeV}}$,...
ABSTRACT High redshift blazars are among the most powerful non-explosive sources in Universe and play a crucial role understanding evolution of relativistic jets. To understand these bright objects, we performed detailed investigation multiwavelength properties 79 γ-ray with redshifts ranging from z = 2.0 to 2.5, using data Fermi LAT, Swift XRT/UVOT, NuSTAR observations. In band, spectral analysis revealed wide range flux photon indices, 5.32 × 10−10 3.40 10−7 cm−2 s−1 1.66 3.15,...
Abstract Blazars are the brightest and most abundant persistent sources in extragalactic γ -ray sky. Due to their significance, they often observed across various energy bands, where data of which can be used explore potential correlations between emission at different energies, yielding valuable insights into processes powerful jets. In this study we utilized IR 3.4 4.6 μ m from Near-Earth Object Wide-field Infrared Survey Explorer Reactivation Mission, spanning 8 yr observations, X-ray...
Abstract We present a comprehensive analysis of the time-resolved spectral energy distributions (SEDs) blazar OJ 287 over 15-year period (2008–2023), using multi-wavelength data. In γ-ray band, multiple flaring episodes were observed, with strongest flare reaching peak flux (5.60 ± 1.11) × 10−7 photons cm−2 s−1 on MJD 55869.03 (04 November 2011). optical/UV source was in an active state between 57360 December 2015) and 57960 (26 July 2017), during which highest (1.07 0.02) 10−10 erg observed...
The detection of high energy (HE) {\gamma}-ray emission up to about 3 GeV from the giant lobes radio galaxy Centaurus A has been recently reported by Fermi-LAT Collaboration based on ten months all-sky survey observations. data set more than three times larger is used here study morphology and photon spectrum with higher statistics. results in HE (up 6 GeV) a significance 10 20 {\sigma} for North South lobe, respectively. Based detailed spatial analysis comparison associated lobes, we report...
Cygnus X-3 (Cyg X-3) is a remarkable Galactic microquasar (X-ray binary) emitting from radio to γ-ray energies. In this paper, we consider the hadronic model of emission γ-rays above 100 MeV and their implications. We focus on joint neutrino production resulting proton–proton interactions within binary system. find that required proton injection kinetic power, necessary explain flux observed by AGILE Fermi-LAT, Lp ∼ 1038 erg s−1, value in agreement with average bolometric luminosity...
Context. Important information on the evolution of a jet can be obtained by comparing physical state plasma at its propagation through broad-line region (where is most likely formed) into intergalactic medium, where it starts to decelerate significantly.