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Publications and source records attributed to a.

4 recordsLinked to original sources

arXiv2020

A Possible $\gamma$-ray Quasi-periodic Oscillation of $\sim$ 314 days in the Blazar OJ 287

We report the detection of a probable $\gamma$-ray quasi-periodic oscillation (QPO) of around 314 days in the monthly binned 0.1 -- 300 GeV $\gamma$-ray {\it Fermi}-LAT light curve of the well known BL Lac blazar OJ 287. To identify and quantify the QPO nature of the $\gamma$-ray light curve of OJ 287, we used the Lomb-Scargle periodogram (LSP), REDFIT, and weighted wavelet z-transform (WWZ) analyses. We briefly discuss possible emission models for radio-loud active galactic nuclei (AGN) that can explain a $\gamma$-ray QPO of such a period in a blazar. Reports of changes in the position of quasi-stationary radio knots over a yearly timescale as well as a strong correlation between gamma-ray and mm-radio emission in previous studies indicate that the signal is probably associated with these knots.

astro-ph.HE↗

arXiv2016

Search for potential precursors for Si-atomic layer deposition- a quantum chemical study

Thin film of silicon is an interesting material for many technological applications in electronic industry and in energy harvesting technologies, but requires a method for controlled growth of thin films. The purpose of this study is to screen a wide variety of Si content precursors for Si ALD reactions using state-of-the-art density-functional calculations. Among the studied 85 Si content precursors we found that C7H12OSi(Methoxy-trivinyl-silane) and C7H9NSi (Benzyliminosilane) show positive indications for ALD reactivity for Si deposition. We believe that this finding will be helpful to develop low-cost, high-energy efficiency thin-film solar cells for future scale up implementation in photovoltaics.

cond-mat.mtrl-sci↗

arXiv2015

MAGIC observations of MWC 656, the only known Be/BH system

Context: MWC 656 has recently been established as the first observationally detected high-mass X-ray binary system containing a Be star and a black hole (BH). The system has been associated with a gamma-ray flaring event detected by the AGILE satellite in July 2010. Aims: Our aim is to evaluate if the MWC 656 gamma-ray emission extends to very high energy (VHE > 100 GeV) gamma rays. Methods. We have observed MWC 656 with the MAGIC telescopes for $\sim$23 hours during two observation periods: between May and June 2012 and June 2013. During the last period, observations were performed contemporaneously with X-ray (XMM-Newton) and optical (STELLA) instruments. Results: We have not detected the MWC 656 binary system at TeV energies with the MAGIC Telescopes in either of the two campaigns carried out. Upper limits (ULs) to the integral flux above 300 GeV have been set, as well as differential ULs at a level of $\sim$5% of the Crab Nebula flux. The results obtained from the MAGIC observations do not support persistent emission of very high energy gamma rays from this system at a level of 2.4% the Crab flux.

astro-ph.HE↗

arXiv2006

Response to the comment by N. Severijns, O. Zimmer, H.-F. Wirth and D. Rich regarding article "Observation of the neutron radiative decay" in JETP Letters 83(1) p.5

We wouldn't like to bring up discrimination, but the tone of the commentary, which does not contain any science-based criticism or any alternative suggestions, does make one think of an unduly disrespectful attitude both towards the Russian participants and the project on radiative neutron decay itself. Here we cite our response to the commentary of our Western collaborants to the article printed in JETP Letters 83(1) p.5. We remain firm in the positions published in this article. In our last experiment we measured the relative intensity of radiative neutron decay (B.R.=(3.2+-1.6) 10-3 with C.L.=99.7% and lower energy limit of radiative gamma-quanta measured equal to 35 KeV) .

nucl-ex↗