ABSTRACT
We present the first sample of tidal disruption events (TDEs) discovered during the SRG all-sky survey. These 13 events were selected among X-ray transients detected in the 0° < l < 180° ...hemisphere by eROSITA during its second sky survey (2020 June 10 to December 14) and confirmed by optical follow-up observations. The most distant event occurred at z = 0.581. One TDE continued to brighten at least 6 months. The X-ray spectra are consistent with nearly critical accretion on to black holes of a few ×103 to $10^8\, \mathrm{ M}_\odot$, although supercritical accretion is possibly taking place. In two TDEs, a spectral hardening is observed 6 months after the discovery. Four TDEs showed an optical brightening apart from the X-ray outburst. The other nine TDEs demonstrate no optical activity. All 13 TDEs are optically faint, with Lg/LX < 0.3 (Lg and LX being the g band and 0.2–6 keV luminosity, respectively). We have constructed a TDE X-ray luminosity function, which can be fit by a power law with a slope of −0.6 ± 0.2, similar to the trend observed for optically selected TDEs. The total rate is estimated at (1.1 ± 0.5) × 10−5 TDEs per galaxy per year, an order of magnitude lower than inferred from optical studies. This suggests that X-ray bright events constitute a minority of TDEs, consistent with models predicting that X-rays can only be observed from directions close to the axis of a thick accretion disc formed from the stellar debris. Our TDE detection threshold can be lowered by a factor of ∼2, which should allow a detection of ∼700 TDEs by the end of the SRG survey.
The amplitude and width of the ultrashort pulses depend on the performance of the generator's electronic elements. The usage of step recovery diodes (SRDs) with picosecond switching time can lead to ...a significant increase in device cost. In this letter, nonlinear transmission line (NLTL) was built and tested using commercial-off-the-shelf components to improve the performance of the generator that is based on inexpensive diodes. The method to control output pulse duration by keeping the constant amplitude was proposed. Measurement results show that generated ultrashort pulse can be compressed using NLTLs and the output amplitude of the compressed pulse is 54 V and the duration is 240 ps.
We studied the effect of antiviral agent riamilovir on ADP-induced platelet aggregation in the absence and presence of LPS. Unlike acetylsalicylic acid (reference drug), riamilovir did not exhibit ...antiplatelet effect
in vitro
. However, it markedly suppressed platelet reactivity in LPS-treated blood samples and was 2.2-fold superior to acetylsalicylic acid in terms of IC
50
value. In
in vivo
experiments, riamilovir under conditions of hypercytokinemia blocked platelet aggregation in rats by 64%.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Operation of ultrashort pulse generator based on an inductive energy storage and semiconductor opening switch (diode with charge storage) is analyzed. Parameters of the generator circuit and working ...regime are optimized to reach maximum amplitudes of the output pulses. Application of trailing-edge shaper based on a step recovery diode is proposed to decrease the pulse duration. Experimental results for the proposed system show that pulses with a FWHM of 230 ps and an amplitude of 70 V can be generated.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In the fall of 2019, during the in-flight calibration phase of the SRG observatory, the onboard eROSITA and Mikhail Pavlinsky ART-XC telescopes carried out a series of observations of PG 1634+706 — ...one of the most luminous (an X-ray luminosity
erg s
) quasars in the Universe at
. Approximately at the same dates this quasar was also observed by the XMM-Newton observatory. Although the object had already been repeatedly studied in X-rays previously, its new observations allowed its energy spectrum to be measured more accurately in the wide range 1–30 keV (in the quasar rest frame). Its spectrum can be described by a two-component model that consists of a power-law continuum with a slope
and a broadened iron emission line at an energy of about 6.4 keV. The X-ray variability of the quasar was also investigated. On time scales of the order of several hours (here and below, in the source rest frame) the X-ray luminosity does not exhibit a statistically significant variability. However, it changed noticeably from observation to observation in the fall of 2019, having increased approximately by a factor of 1.5 in 25 days. A comparison of the new SRG and XMM-Newton measurements with the previous measurements of other X-ray observatories has shown that in the entire 17-year history of observations of the quasar PG 1634+706 its X-ray luminosity has varied by no more than a factor of 2.5, while the variations on time scales of several weeks and several years are comparable in amplitude.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
We present the results of our identification of 14 X-ray sources detected in the eastern Galactic sky (
) in the 4–12 keV energy band on the combined map of the first five all-sky surveys (from ...December 2019 to March 2022) with the Mikhail Pavlinsky ART-XC telescope onboard the SRG observatory. All 14 sources are reliably detected by the SRG/eROSITA telescope in the 0.2–8 keV energy band. Six of them have been detected in X-rays for the first time, while the remaining ones have already been known previously as X-ray sources, but their nature has remained unknown. We have taken optical spectra for 12 sources with the 1.6-m AZT-33IK telescope at the Sayan Observatory (the Institute of Solar–Terrestrial Physics, the Siberian Branch of the Russian Academy of Sciences). For two more objects we have analyzed the archival spectra taken during the 6dF survey. All objects have turned out to be Seyfert galaxies (one NLSy1, three Sy1, four Sy1.9, and six Sy2) at redshifts
–0.238. Based on data from the eROSITA and ART-XC telescopes onboard the SRG observatory, we have obtained X-ray spectra for all objects in the energy range 0.2–12 keV. In four of them the intrinsic absorption exceeds
cm
at a 90
confidence level, with one of them being probably heavily obscured (
cm
with 90
confidence). This paper continues our series of publications on the identification of hard X-ray sources detected during the all-sky survey with the SRG orbital X-ray observatory.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
We present the results of our identification of 17 X-ray sources detected in the 4–12 keV energy range by the Mikhail Pavlinsky ART-XC telescope during the first year of the SRG all-sky survey. Three ...of them have been discovered by the ART-XC telescopes, while the remaining ones have already been known previously as X-ray sources, but their nature has remained unknown. We took optical spectra for nine sources located in the northern sky (
) with the 1.6-m AZT-33IK telescope at the Sayan Observatory (the Institute of Solar–Terrestrial Physics, the Siberian Branch of the Russian Academy of Sciences) and the 1.5-m Russian–Turkish telescope at the TÜBITAK National Observatory. For the remaining objects we have analyzed the archival optical spectra taken during the 6dF survey. All of the investigated objects have turned out to be Seyfert galaxies (eight of type 1, seven of type 2, and two of intermediate type 1.8) at redshifts up to
. Based on data from the eROSITA and ART-XC telescopes onboard the SRG observatory, we have obtained X-ray spectra in the energy range 0.2–20 keV for eight sources. A significant intrinsic absorption (
cm
) has been detected in three of them, with two of them being probably strongly absorbed (
cm
). This paper is a continuation of the series of publications on the optical identification of active galactic nuclei detected by the ART-XC telescope.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
8.
Use of a mineral additive in cattle feeding Sukhanova, S F; Uskov, G E; Lushnikov, N A
IOP conference series. Earth and environmental science,
10/2019, Volume:
341, Issue:
1
Journal Article
Peer reviewed
Open access
Mineral additives on the basis of domestic natural minerals, products of chemical and microbiological production are developed. At calculation of structure of additives the daily requirement of ...animals for mineral substances taking into account a direction of productivity, biological and physiological features of an animal in structure of the experimental mineral additive No. 1 includes forage salt, monoammonium phosphate, brusite, chalk and salts of microcells -100 g of this additive allows to provide completely an animal with microcells, and also to compensate lack of phosphorus, calcium, sodium and magnesium. Mineral additive No. 2 in the amount of 300 g provides the animal's need for trace elements. In addition, this additive includes a daily rate of feed salt and 60% of calcium, phosphorus and magnesium requirements. Therefore, the use of this additive makes it possible to almost fully meet the needs of animals in feed salt, macro- and microelements. Feeding experimental mineral additives to animals allowed increasing milk production during the break-up period by 3.9 and 6.6%, respectively. Balanced mineral nutrition reduced the duration of the service period by 10.2 and 15.8% in the pilot groups. The use of new mineral additives in the diet led to a decrease in production costs by 2.65 and 3.94%. In the end, all this led to an increase in the profitability of milk production: in the control group it was 21.02%, and in the experimental group it was by 3.79% and 5.85% more, respectively. Thus, thanks to the use of new types of mineral additives, animal productivity has increased, feed consumption per unit of production has decreased, milk quality has improved and profitability of production has increased.
Systems of quantum spins
with isotropic Heisenberg interaction play an important role in physics. In studying such systems, it may be useful to have a complete, yet non-overcomplete, basis of ...operators each of which has the symmetry of the Hamiltonian, i.e., is invariant with respect to rotations (global
transformations of the Pauli matrices). This paper presents an algorithm for constructing such a basis. The algorithm is implemented in Wolfram Mathematica.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
We discuss the results of our spectroscopy for 17 candidates for distant quasars selected by the SRGz classification system based on data from the first and second sky surveys with the eROSITA ...telescope onboard the SRG X-ray observatory. Most of the quasar candidates were selected within the DaLeQo observing program, whose goal is a search for the most X-ray luminous quasars with luminosities
erg s
at redshifts
. Our spectroscopic observations were carried out at the 6-m BTA telescope with the SCORPIO-2 spectrograph. We have managed to confirm eight new X-ray quasars at
, including the quasar SRGe J020142.8-015347 at
. Owing to the large diameter of the BTA mirror and the high quantum efficiency of the SCORPIO-2 spectrograph in the range 6000–9000 Å, we have managed to measure the С IV (1549 Å) line parameters and to estimate the supermassive black hole masses and accretion rates for seven quasars.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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