Elena Fedorova

National Institute of Astrophysics | INAF · Astronomical Observatory of Rome

A deep survey of the Large Magellanic Cloud at ∼0.1–100 TeV photon energies with the Cherenkov Telescope Array is planned. We assess the detection prospects based on a model for the emission of the galaxy, comprising the four known TeV emitters, mock populations of sources, and interstellar emission on galactic scales. We also assess the detectabil...

The 3C120 (Mrk 1506, UGC 03087, Mrk 9014) is a type 1 Seyfert (Sy1)/broad-line radio galaxy (BLRG) with intriguing variable jet activity featuring “dip” and “outburst” phases. Significant X-ray observational datasets have been collected for 3C120 by INTEGRAL, XMM-Newton, SWIFT, Suzaku, and other X-ray observational facilities. The overall X-ray spe...

The local Cosmic Ray (CR) energy spectrum exhibits a spectral softening at energies around 3~PeV. Sources which are capable of accelerating hadrons to such energies are called hadronic PeVatrons. However, hadronic PeVatrons have not yet been firmly identified within the Galaxy. Several source classes, including Galactic Supernova Remnants (SNRs), h...

The main idea of our research is to estimate the physical coalescence time of the double supermassive black hole (SMBH) system in the centre of NGC 6240 based on the X-ray observations from the Chandra space observatory. The spectra of the Northern and Southern nuclei were fitted by spectral models from Sherpa and both presented the narrow componen...

The main idea of our research is to estimate the physical coalescence time of the double supermassive black hole (SMBH) system in the centre of NGC 6240 based on the X-ray observations from the Chandra space observatory. The spectra of the Northern and Southern nuclei were fitted by spectral models from Sherpa and both presented the narrow componen...

We consider the sample of 55 blazars and Seyferts cross-correlated from the Planck all-sky survey based on the Early Release Compact Source Catalog (ERCSC) and Swift BAT 105-Month Hard X-ray Survey. The radio Planck spectra vs. X-ray Swift/XRT+BAT spectra of the active galactic nuclei (AGN) sample were fitted with the simple and broken power law (f...

Astrophysical observations provide strong evidence that more than 80% of all matter in the Universe is in the form of dark matter (DM). Two leading candidates of particles beyond the Standard Model that could constitute all or a fraction of the DM content are the so-called Weakly Interacting Massive Particles (WIMPs) and Axion-Like Particles (ALPs)...

The discovery of gravitational waves, high-energy neutrinos or the very-high-energy counterpart of gamma-ray bursts has revolutionized the high-energy and transient astrophysics community. The development of new instruments and analysis techniques will allow the discovery and/or follow-up of new transient sources. We describe the prospects for the...

The physics of the non-thermal Universe provides information on the acceleration mechanisms in extreme environments, such as black holes and relativistic jets, neutron stars, supernovae or clusters of galaxies. In the presence of magnetic fields, particles can be accelerated towards relativistic energies. As a consequence, radiation along the entir...

We provide an updated assessment of the power of the Cherenkov Telescope Array (CTA) to search for thermally produced dark matter at the TeV scale, via the associated gamma-ray signal from pair-annihilating dark matter particles in the region around the Galactic centre. We find that CTA will open a new window of discovery potential, significantly e...

3C111 is BLRG with signatures of both FSRQ and Sy1 in X-ray spectrum. The significant X-ray observational dataset was collected for it by INTEGRAL, XMM-Newton, SWIFT, Suzaku and others. The overall X-ray spectrum of 3C 111 shows signs of a peculiarity with the large value of the high-energy cut-off typical rather for RQ AGN, probably due to the jet...

The Cherenkov Telescope Array (CTA) is the major next-generation observatory for ground-based very-high-energy gamma-ray astronomy. It will improve the sensitivity of current ground-based instruments by a factor of five to twenty, depending on the energy, greatly improving both their angular and energy resolutions over four decades in energy (from...

The Cherenkov Telescope Array (CTA) is the major next-generation observatory for ground-based very-high-energy gamma-ray astronomy. It will improve the sensitivity of current ground-based instruments by a factor of five to twenty, depending on the energy, greatly improving both their angular and energy resolutions over four decades in energy (from...

213 pages, including references and glossary. Version 2: credits and references updated, some figures updated, and author list updated

We analyze the hard X-ray properties of five radio-loud active galactic nuclei with peculiar spectral shape. High-energy exponential cut-offs (HEC) in their hard X-ray 3-500 keV spectra are too high for radio loud AGNs (above 100 keV) or even absent.The probable reason of such visible spectral “peculiarity” can be due to the “jet contamination”, i....

The line profiles like that of the fluorescent Fe K or Co K lines in the X-ray spectra of the active galactic nuclei (AGN) reflect characteristics of the central regions of these objects. These lines can be formed in the accretion disks around central supermassive black holes and their shapes are connected with the central black hole spin and the a...

Mapping the maser emission of subnuclear regions of active galactic nuclei (AGN) enable us to determine some interesting details of the geometry of the accretion disks (AD) under the condition that they have “maser skin”. Additional information about disk warp in the innermost zone near the central black hole (BH) can be disclosed by means of model...

We analysed how the active galactic nucleus (AGN) X-ray primary continuum depends on AGN activity in radio, using the data of RXTE Spectral & Timing Database (Rossi X-ray Timing Explorer) and INTEGRAL (INTErnational Gamma-Ray Astrophysics Laboratory). Our aim is to test the relation between spectral shapes of these AGNs and the prediction of the "s...

We perform simulations for future Cherenkov Telescope Array (CTA) observations of RX J1713.7-3946, a young supernova remnant (SNR) and one of the brightest sources ever discovered in very high energy (VHE) gamma rays. Special attention is paid to exploring possible spatial (anti)correlations of gamma rays with emission at other wavelengths, in part...

We perform simulations for future Cherenkov Telescope Array (CTA) observations of RX J1713.7‑3946, a young supernova remnant (SNR) and one of the brightest sources ever discovered in very high energy (VHE) gamma rays. Special attention is paid to exploring possible spatial (anti)correlations of gamma rays with emission at other wavelengths, in part...

We analysed the broadband light curves of the flat spectrum radio quasar (FSRQ) 3C 273 between September 2008 and August 2012. The discrete correlation function (DCF) probed the correlation between light curves at different frequencies. This method showed a correlation between the gamma-ray emission and the radio mm-emission, as well as with the op...

In this paper, we analyze all the available X-ray photometrical data of the narrow-line Seyfert 1 galaxy NGC 4748, namely XMM-Newton (EPIC and OM), INTEGRAL (ISGRI and JEM-X) as well as SWIFT (BAT and XRT) to estimate, if it's possible, the mass of the central black hole from the variability of the lightcurves. In the XMM/EPIC composite lightcurve,...

Strong gravitational microlensing (GM) events provide us a possibility to determine both the parameters of microlensed source and microlens. GM can be an important clue to understand the nature of dark matter on comparably small spatial and mass scales (i.e. substructure), especially when speaking about the combination of astrometrical and photomet...

Results of 11-year-long X-ray INTEGRAL observations of the nucleus of Seyfert galaxy NGC 4945 in the 3–500 keV range were processed. A two-component spectrum model, which includes strong radiation absorption in the Compton-thick torus around the AGN “central engine” and secondary radiation reflected from the torus walls, was used in the analysis. T...

Detailed investigation of broadband flux variability in the blazar 3C 273 allows us to probe the location and size of emission regions and their physical conditions. We report the results on correlation studies of the flaring activity observed between 2008 and 2012. The observed broadband variations were investigated using the structure function an...

We analyze the X-ray properties of the Compton-thick Seyfert 1.9 radio quiet AGN in NGC 1194 using INTEGRAL (ISGRI), XMM-Newton (EPIC), Swift (BAT and XRT), and Suzaku (XIS) observations. There is a set of Fe-K lines in the NGC 1194 spectrum with complex relativistic profiles that can be considered as a sign of either a warped Bardeen-Petterson acc...

Extended dark matter (DM) substructures may play the role of microlenses in the Milky Way and in extragalactic gravitational lens systems (GLSs). We compare microlensing effects caused by point masses (Schwarzschild lenses) and extended clumps of matter using a simple model for the lens mapping. A superposition of the point mass and the extended cl...

Active galactic nuclei (AGN) are the brightest objects in the Universe and their brightness is mainly caused by accretion of matter onto supermassive black holes (SMBH). This is the common reason of the AGN activity. However, every AGN has differences and fine features, which are the subject of an intensive investigation. The occurrence of such hig...

We present a broadband X-ray analysis of a new homogeneous sample of 95 active galactic nuclei (AGN) from the 22-month Swift/BAT all-sky survey. For this sample we treated jointly the X-ray spectra observed by XMM-Newton and INTEGRAL missions for the total spectral range of 0.5-250 keV. Photon index \Gamma, relative reflection R, equivalent width o...

Gravitational microlensing of a distant source by a stochastic system of point masses (stars) and extended masses that model dark-matter clumps is analyzed. The size of each clump is set to be equal to 5 or 10 Einstein radii. A total of 100 realizations of the magnification map are generated under the assumption of a spatially homogeneous distribut...

Based on the data obtained with the XMM-Newton and INTEGRAL space telescopes, some properties of the X-ray emission from active nucleus of NGC 1194 galaxy are analyzed. Particular attention is paid to the X-ray energy spectrum from 6 to 7.5 keV. In this case, besides FeK α (6.38 keV) and FeK β (7.01 keV) fluorescent lines, an additional line with a...

We compare a microlensing of a remote point source on point-like objects (stars or black holes) and on clumps of dark matter of a non-zero size described by circularly symmetric " toy models ". The microlensing of the source by one clump is considered in detail. We look for astrometric and photometric features of the microlensing, which depend sign...

We present here the results of our analysis of X-ray properties of Seyfert 2 galaxy NGC 3281, based on the observational data obtained by XMM-Newton and INTEGRAL within the energy ranges 0.2-12 keV and 20-150 keV, respectively. The XMM-Newton spectrum of this object is presented for the first time. We show that fitting the X-ray spectrum of this ga...

We review experimental confirmations of the General Relativity theory (GRT) and discuss problems concerning applications of GRT in strong gravitational fields. The tests of GRT in the Solar system and in the double star systems containing pulsars are analysed. We formulate some problems that arise in theoretical considerations of compact astrophysi...

We present results of our analysis of the XMM-Newton and Swift observations of the galaxy with Sy 1.9 active nucleus Mrk 1498. We analyze the spectra obtained from three EPIC cameras (PN and both MOS) within the 0.2–12 keV energy range and Swift/BAT instrument within the range of 14-195 keV. We demonstrate that for the X-ray spectrum of the AGN in...

We develop a method to construct the reference system (RS) of a local observer which is based on the transformation from the instant normal coordinates to the Fermi and optical ones. The main advantage of our approach is due to a direct relation of the optical coordinates with observable positions of distant objects on the celestial sphere. The met...

The Workshop on results of the Project Kosmomikrofizyka-2 (Astroparticle Physics) of the National Academy of Sciences (NAS) of Ukraine "Astrophysical and cosmological problems of invisible mass and dark energy in the Universe" was held on November 21-22, 2012 in the Institute for Nuclear Research, Kyiv, Ukraine (http://lpd.kinr.kiev.ua/kmf12). This...

The most accepted model to explain the nature of RQ/RL dichotomy of AGN isthe so-called spin paradigm, which explains the jets and powerful radio emission ofRQ objects as an effect of higher values of BH spin comparably to RQ ones. One ofthe observational differences between RQ and RL AGN predicted by spin-paradigmlies in the form of the hard X-ray...

We discuss analytical results dealing with photometric and astrometric gravitational microlensing. The first two sections concern approximation methods that allow us to get solutions of the general lens equation near fold caustics and cusp points up to any prescribed accuracy. Two methods of finding approximate solutions near the fold are worked ou...

We analyze the X-ray properties of Compton thick Seyfert 1.9 Radio quiet AGN in NGC 1194 from both the INTEGRAL/ISGRI and XMM-Newton observational data, paying the special attention to the set of iron emission lines between 6 and 7.5 keV. No statistically significant flux variability was found. Three emission lines can be resolved in this range, ne...

We present analysis results on the Seyfert 2 galaxy NGC 4388 based on 6 yr of INTEGRAL data combined with Swift/Burst Alert Telescope survey and Swift/X-Ray Telescope pointed observations. These data, taken from 2003 to 2009, allow us to study the broad-band properties of this active galactic nucleus in the 0.3–300 keV energy range. The continuum e...

Long-term monitoring data at five radio frequencies from 4.8 to 37 GHz obtained at the Crimean Astrophysical Observatory, Metsahovi Radio Observatory of Aalto University, and the University of Michigan Radio Astronomy Observatory are used to analyze variations of the flux of the Active Galactic Nucleus (AGN) 3C 454.3. The dynamical characteristics...

An approximate formula for the magnification of a point source near a fold caustic obtained in the first linear caustic approximation is widely used in the theory of gravitational lens systems. Here, this formula is refined to include the post-linear terms that have been found both for a point source and for an extended Gaussian source in the absen...

The analysis of INTEGRAL IBIS/ISGRI and JEM-X data obtained during six years (from 2003 to 2009) of the Seyfert 2 galaxy NGC 4388 indicates that both X-ray flux and the shape of the broadband 3–300 keV spectrum are variable. The averaged X-ray to soft γ-ray continuum emis-sion of NGC 4388 is well represented by an absorbed cut-off power-law model,...

X-ray observations of gravitationally lensed quasars may allow us to probe the inner structure of the central engine of a quasar. Observations of Q2237+0305 (Einstein Cross) in X-rays may be used to constrain the inner structure of the X-ray emitting source. Here we analyze the XMM-Newton observation of the quasar in the gravitational lens system Q...

Theoretical basis of the General Relativity theory (GR), its experimental tests as well as GR applications were briefly summarized in the new textbook devoted to the World Year of Physics-2005 (authors - Yatskiv Ya.S., Alexandrov A.N., Vavilova I.B., Zhdanov V.I., Kudrya Yu.N., Parnovsky S.L., Fedorova E.V., Khmil S.V., Kyiv:Akademperiodika, 2005,...

We analyze a reliability of quasar brightness distribution (BD) parameter estimation on the light curves of different images in the system Q2237+0305 observed by OGLE and GLITP groups during High Amplification Events (HAE). We evaluated the source parameters for as small as possible data interval in the neighborhood of HAE under supposition of powe...

Gravitational field of stars of the Galaxy causes additional motions of images of extragalactic sources. For typical realization of stars this results in a small rotation of extragalactic reference frame in the direction of Galactic rotation. We estimate angular velocity of corresponding image motion and show that it is different in case of discret...

It is shown that gravitational field of moving stars induces a small systematic image motion of extragalactic objects in the galactic plane (of the order of 0.1 muas/yr in maximum). The effect depends essentially on either the mass is located in compact objects or the mass distribution is continuous.

Gravitational field of foreground stars of the Galaxy causes additional motion of images of extragalactic sources. We estimate characteristics of stochastic and average motions of these images. The probability distribution for the image motions and their changes is obtained for general spatial density of microlenses. We show that collective motion...

We consider the motion of the image of a distant radiation source microlensed by one and many point masses in the presence of an external background field, which produces a shear in the lens equation. The trajectories of the image brightness centroid (BC) in a Chang-Refsdal lens are very sensitive to the magnitude of the shear and to the direction...