Papers by Sergei Grebenev
Space Telescopes and Instrumentation 2018: Ultraviolet to Gamma Ray
ART-XC is an X-ray grazing incidence mirror telescopes array onboard the Spectrum-Roentgen-Gamma ... more ART-XC is an X-ray grazing incidence mirror telescopes array onboard the Spectrum-Roentgen-Gamma (SRG) mission, that is currently scheduled for launch in March 2019. This instrument was developed by the Space Research Institute (IKI) and the All-Russian Scientific Research Institute for Experimental Physics (VNIIEF). The NASA Marshall Space Flight Center (MSFC) has developed and fabricated flight X-ray mirror modules. Each mirror module is aligned with a focal plane CdTe double-sided strip detector which will operate over the energy range of 4−30 keV, with an angular resolution of <1′, a field of view of ~0.3 deg2 in double reflection and an expected energy resolution of about 9% at 14 keV. The ART-XC instrument will be used to perform an all-sky survey simultaneously with the other instrument of the SRG mission, eROSITA, operational in a softer energy range 0.3-10 keV. We present an overview of the ARTXC/SRG instrument and an update on the current status of the project.
arXiv: High Energy Astrophysical Phenomena, 2019
Gamma-ray astronomy explores the most energetic photons in nature to address some of the most pre... more Gamma-ray astronomy explores the most energetic photons in nature to address some of the most pressing puzzles in contemporary astrophysics. It encompasses a wide range of objects and phenomena: stars, supernovae, novae, neutron stars, stellar-mass black holes, nucleosynthesis, the interstellar medium, cosmic rays and relativistic-particle acceleration, and the evolution of galaxies. MeV gamma-rays provide a unique probe of nuclear processes in astronomy, directly measuring radioactive decay, nuclear de-excitation, and positron annihilation. The substantial information carried by gamma-ray photons allows us to see deeper into these objects, the bulk of the power is often emitted at gamma-ray energies, and radioactivity provides a natural physical clock that adds unique information. New science will be driven by time-domain population studies at gamma-ray energies. This science is enabled by next-generation gamma-ray instruments with one to two orders of magnitude better sensitivity,...
New Astronomy Reviews, 2019
High mass X-ray binaries are among the brightest X-ray sources in the Milky Way, as well as in ne... more High mass X-ray binaries are among the brightest X-ray sources in the Milky Way, as well as in nearby Galaxies. Thanks to their highly variable emissions and complex phenomenology, they have attracted the interest of the high energy astrophysical community since the dawn of X-ray Astronomy. In more recent years, they have challenged our comprehension of physical processes in many more energy bands, ranging from the infrared to very high energies. In this review, we provide a broad but concise summary of the physical processes dominating the emission from high mass X-ray binaries across virtually the whole electromagnetic spectrum. These comprise the interaction of stellar winds with the high gravitational and magnetic fields of compact objects, the behaviour of matter under extreme magnetic and gravity conditions, and the perturbation of the massive star evolutionary processes by presence in a binary system. We highlight the role of the INTEGRAL mission in the discovery of many of the most interesting objects in the high mass X-ray binary class and its contribution in reviving the interest for these sources over the past two decades. We show how the INTEGRAL discoveries have not only contributed to significantly increase the number of high mass X-ray binaries known, thus advancing our understanding of the population as a whole, but also have opened new windows of investigation that stimulated the multi-wavelength approach nowadays common in most astrophysical research fields. We conclude the review by providing an overview of future facilities being planned from the X-ray to the very high energy domain that will hopefully help us in finding an answer to the many questions left open after more than 18 years of INTEGRAL scientific observations.
Proceedings of An INTEGRAL view of the high-energy sky (the first 10 years) - 9th INTEGRAL Workshop and celebration of the 10th anniversary of the launch — PoS(INTEGRAL 2012), 2013
Proceedings of The Extreme sky: Sampling the Universe above 10 keV — PoS(extremesky2009), 2010
We report results of the INTEGRAL Target of Opportunity observations of the transient X-ray burst... more We report results of the INTEGRAL Target of Opportunity observations of the transient X-ray burster XTE J1810-189. The observations were performed on April 3-6, 2008, soon after the discovery of the source and near the peak of its outburst. That time the source had a flux of about 50 mCrab and exhibited a hard Comptonized X-ray spectrum extending well above 100 keV. Being approximated by a power law with an exponetial cutoff in the broad 3-100 keV energy band it gave the average photon index Γ ≃ 1.6 and kT cuto f f ≃ 67 keV. We found only slight indications for changes in the index during the observation (Γ first steady decreased from * Speaker.
Proceedings of The Extreme sky: Sampling the Universe above 10 keV — PoS(extremesky2009), 2010
… New science will be driven by time-domain population studies at MeV γ-ray energies. This scienc... more … New science will be driven by time-domain population studies at MeV γ-ray energies. This science is enabled by next-generation γ-ray instruments with one to two orders of magnitude better sensitivity, larger sky coverage, and faster cadence than all previous γ-ray instruments. This transformative capability …
AIP Conference Proceedings, 1991
Results of the supernova 1987A hard X-ray observations in 1987-1990 with Mir-Kvant and Granat are... more Results of the supernova 1987A hard X-ray observations in 1987-1990 with Mir-Kvant and Granat are presented. They make it possible to estimate the degree of Co-56 mixing over the envelope and set hard restrictions on abundances of radioactive Co-57, Ti-44, and Na-22 produced during the outburst. The upper limit at three standard deviation level on the Co-57/Co-56 ratio inside the
AIP Conference Proceedings, 1994
Observations of Galactic black hole candidates performed with the ART‐P telescope aboard Granat i... more Observations of Galactic black hole candidates performed with the ART‐P telescope aboard Granat in 1990–1992 focused our attention on studying of the sources spectral variability vs the accretion rate. We show that in contrast with the current scenario of disk accretion onto a black hole the hard spectral state of the sources always occurs at smaller accretion rate than the soft state. The arguments are presented that hard x‐rays detected during the ‘‘very high’’ and ‘‘low’’ states of black hole candidates have a distinct origin.
AIP Conference Proceedings, 2008
Supergiant Fast X-ray Transients are obviously related to persistent Supergiant Xray Binaries. An... more Supergiant Fast X-ray Transients are obviously related to persistent Supergiant Xray Binaries. Any convincing explanation for their behaviour must consistently take into account all types of X-ray sources powered by wind accretion. Here we present a common framework for wind accreting sources, within the context of clumpy wind models, that allows a coherent interpretation of their different behaviours as an immediate consequence of diverse orbital geometries.
Astronomy Letters, 2013
The discovery of a new X-ray source, IGR J18175-2419, that flared up for a short (∼1 h) time on S... more The discovery of a new X-ray source, IGR J18175-2419, that flared up for a short (∼1 h) time on September 26, 2012, by the INTEGRAL observatory is reported. The results of the source’s localization and the spectral/timing analysis of its X-ray emission are presented. The source may turn out to be yet another representative of the population of fast X-ray transients, which is the focus of attention due to the identification of their optical counterparts with early-type supergiants.
Astronomy Letters, 2010
Details of the discovery (in February 2004) and results of subsequent (in 2004–2009) INTEGRAL obs... more Details of the discovery (in February 2004) and results of subsequent (in 2004–2009) INTEGRAL observations of the transient X-ray burster IGR J17380-3749 (IGR J17379-3747) are presented. Over the period of its observations, the INTEGRAL observatory recorded two hard X-ray flares and one type I X-ray burst from the source, which allowed the nature of IGR J17380-3749 to be determined. The burster radiation spectrum during the flares was hard—a power law with a photon index α = 1.8–2.0 or bremsstrahlung corresponding to a plasma with a temperature kT = 90–140 keV. The spectral shape at the flare peaks turned out to be the same, despite a more than twofold difference in flux (the peak flux recorded in the energy range 18–100 keV reached ∼20 mCrab). The upper limit on the flux from the source in its quiescent (off) state in the range of 18–40 keV was 0.15 mCrab (3σ).
NATO Science Series II. Mathematics, Physics and Chemistry
Astronomy Letters, 2015
Results of the study of the X-ray nova SWIFT J174510.8-262411 by the INTEGRAL, SWIFT, and VLA obs... more Results of the study of the X-ray nova SWIFT J174510.8-262411 by the INTEGRAL, SWIFT, and VLA observatories in September-October 2012 at the early outburst phase are presented. Attention is focused on analyzing the power spectrum of X-ray flux fluctuations of the source in which a powerful quasi-periodic oscillation (QPO) peak has been detected. The evolution of the QPO peak parameters with time has been traced; a correlation between the QPO frequency, low-frequency noise (LFN) parameters, X-ray and radio fluxes, and fractional polarization of radio emission has been revealed. The fractal properties of the source's light curves in the standard X-ray band (<10 keV) are shown to change with QPO peak frequency. In the hard X-ray band (20-80 keV), the source's light curves have no fractal properties, despite the larger QPO and LFN amplitude than that in the standard X-ray band. The observational results can be explained by assuming that the source's X-ray emission is formed in a hot plasma cloud surrounding a black hole, while the QPOs are produced at its boundary, at the place of contact with the accretion disk; their frequency reflects the Keplerian rotation of matter at the corresponding radius.
Imaging in High Energy Astronomy, 1995
We discuss the use of a wavelet transform for the subtraction of nonuniform background and for fi... more We discuss the use of a wavelet transform for the subtraction of nonuniform background and for filtering images obtained with the coded-mask X-ray telescope ART-P aboard the Granat spacecraft.
The Astrophysical Journal, 2015
The whole set of INTEGRAL observations of type Ia supernova SN2014J, covering the period 19-162 d... more The whole set of INTEGRAL observations of type Ia supernova SN2014J, covering the period 19-162 days after the explosion has being analyzed. For spectral fitting the data are split into early and late periods covering days 19-35 and 50-162, respectively, optimized for 56 Ni and 56 Co lines. As expected for the early period much of the gamma-ray signal is confined to energies below ∼200 keV, while for the late period it is most strong above 400 keV. In particular, in the late period 56 Co lines at 847 and 1248 keV are detected at 4.7 and 4.3 σ respectively. The lightcurves in several representative energy bands are calculated for the entire period. The resulting spectra and lightcurves are compared with a subset of models. We confirm our previous finding that the gamma-ray data are broadly consistent with the expectations for canonical 1D models, such as delayed detonation or deflagration models for a near-Chandrasekhar mass WD. Late optical spectra (day 136 after the explosion) show rather symmetric Co and Fe lines profiles, suggesting that unless the viewing angle is special, the distribution of radioactive elements is symmetric in the ejecta.
Nature, Jan 28, 2014
A type Ia supernova is thought to be a thermonuclear explosion of either a single carbon-oxygen w... more A type Ia supernova is thought to be a thermonuclear explosion of either a single carbon-oxygen white dwarf or a pair of merging white dwarfs. The explosion fuses a large amount of radioactive (56)Ni (refs 1-3). After the explosion, the decay chain from (56)Ni to (56)Co to (56)Fe generates γ-ray photons, which are reprocessed in the expanding ejecta and give rise to powerful optical emission. Here we report the detection of (56)Co lines at energies of 847 and 1,238 kiloelectronvolts and a γ-ray continuum in the 200-400 kiloelectronvolt band from the type Ia supernova 2014J in the nearby galaxy M82. The line fluxes suggest that about 0.6 ± 0.1 solar masses of radioactive (56)Ni were synthesized during the explosion. The line broadening gives a characteristic mass-weighted ejecta expansion velocity of 10,000 ± 3,000 kilometres per second. The observed γ-ray properties are in broad agreement with the canonical model of an explosion of a white dwarf just massive enough to be unstable to...
Science (New York, N.Y.), Jan 5, 2014
Type Ia supernovae result from binary systems that include a carbon-oxygen white dwarf, and these... more Type Ia supernovae result from binary systems that include a carbon-oxygen white dwarf, and these thermonuclear explosions typically produce 0.5 solar mass of radioactive (56)Ni. The (56)Ni is commonly believed to be buried deeply in the expanding supernova cloud. In SN2014J, we detected the lines at 158 and 812 kiloelectron volts from (56)Ni decay (time ~8.8 days) earlier than the expected several-week time scale, only ~20 days after the explosion and with flux levels corresponding to roughly 10% of the total expected amount of (56)Ni. Some mechanism must break the spherical symmetry of the supernova and at the same time create a major amount of (56)Ni at the outskirts. A plausible explanation is that a belt of helium from the companion star is accreted by the white dwarf, where this material explodes and then triggers the supernova event.
The Astrophysical Journal, 1992
... 6.-Spectra of three bright X-ray transients : Nova Vul X (observations of GSPC, HEXE, and PUL... more ... 6.-Spectra of three bright X-ray transients : Nova Vul X (observations of GSPC, HEXE, and PULSAR X-1 instruments on board MIR-KVANT in 1988, from Sunyaev et at. 1988), 05 2023+338 (TTM, HEXE, and PULSAR X-1 on board MIR-KVANT, 1989, from Sunyaev et al. ...
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Papers by Sergei Grebenev