In 2013 March, a flaring episode from the Crab Nebula lasting ~2 weeks was detected by Fermi-LAT (Large Area Telescope on board the Fermi Gamma-ray Space Telescope). The Very Energetic Radiation ...Imaging Telescope Array System (VERITAS) provides simultaneous observations throughout this period. During the flare, Fermi-LAT detected a 20 fold increase in flux above the average synchrotron flux >100 MeV seen from the Crab Nebula. Simultaneous measurements with VERITAS are consistent with the non-variable long-term average Crab Nebula flux at TeV energies. Assuming a linear correlation between the very high energy flux change >1 TeV and the flux change seen in the Fermi-LAT band >100 MeV during the period of simultaneous observations, the linear correlation factor can be constrained to be at most 8.6 x 10 super(-3) with 95% confidence.
Long-term data (2011–2021) on feeding migrations of hatchery-reared Pacific (pink and chum) salmon in the Sea of Okhotsk and adjacent Pacific waters in the autumn–winter period are summarized. The ...study is based on materials (otolith samples and biological indices) collected during the TINRO trawl surveys and also on international statistics for releases and marking of Pacific salmon at Russian and Japanese salmon hatcheries. The major long-term patterns of intraspecific structure, migration routes, spatial distribution and sizes of catches, and the size–weight characteristics of fish from different regions have been determined for these species. Natural mortality rates of salmon juveniles at the stage of migration from the coastal zone to open sea waters have been estimated at a systemic level for the first time.
The problem of simplifying solution of linear dynamic systems with preset conditions at the edges and internal points of the segment is considered. In this regard a modification technique of the ...existing cascade decomposition method based on obtaining a general formula for the system state and control functions is described. Coefficients of this formula are identified in a recursive way. The formula is presented to obtain the cascade decomposition method and kernel functions of the intermediate step matrices being important for the last step function. Illustratively, a practice-oriented example proves the method advantages in convenience and speed comparing with the conventional method of cascade decomposition.
The Rietveld quantitative phase analysis of the HfO
2
active layer in the Si-sub./SiO
2
/HfO
2
/TiN layered structures has been carried out at different annealing temperatures and dopant types. The ...HfO
2
crystal structure has been additionally examined by transmission electron microscopy. A relationship between the dopant valence and crystalline phases forming in the HfO
2
film has been found. It is shown that the Al doping followed by high-temperature annealing prevents the formation of the tetragonal phase (sp. gr.
P
42/
nmc
) in favor of the formation of the polar orthorhombic phase (sp. gr.
Pca
2
1
). The results obtained can be used in the synthesis of HfO
2
-based ferroelectric films for non-volatile memory systems.
Having matured over a few decades, the IACT technique is now ready to widen its energy domain as well as to increase sensitivity in its core region (0.1-50 TeV) by as much as one order of magnitude ...as compared to existing facilities. This will allow to use γ astronomy to search for dark matter, probe intergalactic space and quantum gravity as well as to make efficient observations of extended sources. The design of a new-generation IACT array is motivated by the key science questions to be addressed and constrained by the cost of the experiment. A number of performance characteristics impact the scientific capabilities, not just point-source sensitivity, but also field-of-view, angular resolution, energy threshold and others, and the optimization of the parameters at fixed cost defines the approach to simulation studies. In this paper, I will highlight IACT array design studies carried through to optimize the array configuration, optical and mechanical designs as well as possible designs for telescope cameras.
We present the results of a multiwavelength observational campaign on the TeV binary system LS I +61degrees 303 with the VERITAS telescope array (>200 GeV), Fermi-LAT (0.3-300 GeV), and Swift/XRT ...(2-10 keV). The data were taken from 2011 December through 2012 January and show a strong detection in all three wavebands. During this period VERITAS obtained 24.9 hr of quality selected livetime data in which LS I +61degrees 303 was detected at a statistical significance of 11.9sigma. These TeV observations show evidence for nightly variability in the TeV regime at a post-trial significance of 3.6sigma. The combination of the simultaneously obtained TeV and X-ray fluxes do not demonstrate any evidence for a correlation between emission in the two bands. For the first time since the launch of the Fermi satellite in 2008, this TeV detection allows the construction of a detailed MeV-TeV spectral energy distribution from LS I +61degrees 303. This spectrum shows a distinct cutoff in emission near 4 GeV, with emission seen by the VERITAS observations following a simple power-law above 200 GeV This feature in the spectrum of LS I +61degrees 303, obtained from overlapping observations with Fermi-LAT and VERITAS, may indicate that there are two distinct populations of accelerated particles producing the GeV and TeV emission.
—Using high-frequency heating, we fabricate wear-resistant boride coatings on 65G steel samples under a layer of P-066 flux-based charge containing boron carbide. The wear resistance of the resulting ...coatings is investigated. An experimental design is used to achieve the optimum charge composition. A technological process is proposed for enhancing the strength of flat knives by HFC boriding, and the hardened knives are subjected to field tests.
We report on the VERITAS observations of the high-frequency peaked BL Lac object 1ES 1959+650 in the period 2007-2011. This source is detected at TeV energies by VERITAS at 16.4 standard deviation ...(sigma) significance in 7.6 hr of observation in a low flux state. A multiwavelength spectral energy distribution (SED) is constructed from contemporaneous data from VERITAS, Fermi-LAT, RXTE PCA, and Swift UVOT. Swift XRT data is not included in the SED due to a lack of simultaneous observations with VERITAS. In contrast to the orphan gamma -ray flare exhibited by this source in 2002, the X-ray flux of the source is found to vary by an order of magnitude, while other energy regimes exhibit less variable emission. A quasi-equilibrium synchrotron self-Compton model with an additional external radiation field is used to describe three SEDs corresponding to the lowest, highest, and average X-ray states. The variation in the X-ray spectrum is modeled by changing the electron injection spectral index, with minor adjustments of the kinetic luminosity in electrons. This scenario produces small-scale flux variability of the order of <, ~2 in the high energy (E > 1 MeV) and very high energy (E > 100 GeV) gamma -ray regimes, which is corroborated by the Fermi-LAT, VERITAS, and Whipple 10 m telescope light curves.
We report the discovery of TeV gamma-ray emission coincident with the shell-type radio supernova remnant (SNR) CTA 1 using the VERITAS gamma-ray observatory. The source, VER J0006+729, was detected ...as a 6.5 standard deviation excess over background and shows an extended morphology, approximated by a two-dimensional Gaussian of semimajor (semiminor) axis 0.degrees30 (0.degrees24) and a centroid 5' from the Fermi gamma-ray pulsar PSR J0007+7303 and its X-ray pulsar wind nebula (PWN). The photon spectrum is well described by a power-law dN/dE = N sub(0)(E/3 TeV) super(-Gamma), with a differential spectral index of Gamma = 2.2 + or - 0.2 sub(stat) + or - 0.3 sub(sys), and normalization N sub(0) = (9.1 + or - 1.3 sub(stat) + or - 1.7 sub(sys)) x 10 super(-14) cm super(-2) s super(-1) TeV super(-1). The integral flux, F sub( gamma ) = 4.0 x 10 super(-12) erg cm super(-2) s super(-1) above 1 TeV, corresponds to 0.2% of the pulsar spin-down power at 1.4 kpc. The energetics, colocation with the SNR, and the relatively small extent of the TeV emission strongly argue for the PWN origin of the TeV photons. We consider the origin of the TeV emission in CTA 1.
The today’s energy density of the induced (second order) gravitational wave background in the frequency region ∼10
−3
–10
3
Hz is constrained using the existing limits on primordial black hole ...production in the early Universe. It is shown, in particular, that at frequencies near ∼40 Hz (which is the region explored by LIGO detector), the value of the induced part of Ω
GW
cannot exceed (1−3) × 10
−7
. The spread of values of the bound is caused by the uncertainty in parameters of the gravitational collapse of black holes.
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