Communications of the Byurakan Astrophysical Observatory最新文献

{"title":"The discrepancy between the values of the Hubble constant and the effect of dark energy on baryonic matter","authors":"H. Harutyunian","doi":"10.52526/25792776-23.70.1-100","DOIUrl":"https://doi.org/10.52526/25792776-23.70.1-100","url":null,"abstract":"It seems clear that researchers have not yet fully appreciated the true implications of the discovery of dark energy for understanding evolutionary processes in the baryonic universe. Based on general physical considerations, we consider here the influence of dark energy on baryon objects at the level of atomic nuclei and elementary particles. For such an analysis, the concept is adopted, according to which the entire baryonic Universe interacts with dark energy on all cosmic scales. The consequences seem quite dramatic, since the accumulation of energy in the baryon world changes the energy balance and reduces the binding energy of all objects, including atomic nuclei. Consequently, the nuclear mass defect decreases, their mass increases, and both effects make the nuclei more and more unstable. This leads to the destabilization of all nuclei and their gradual transfer to the stage of radioactive decay, which increases over time the relative amount of light elements, including hydrogen. Evolution under the influence of dark energy, on the other hand, increases the masses of atomic nuclei. We have used this hypothetical effect to interpret the so-called ”Hubble tension” paradox. This also makes it possible to estimate the growth of the proton mass due to dark energy.","PeriodicalId":412578,"journal":{"name":"Communications of the Byurakan Astrophysical Observatory","volume":"78 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128598445","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Of the new opportunity of solving the Ambartsumian’s functional equation in the theory of radiative transfer","authors":"H. V. Pikichyan","doi":"10.52526/25792776-23.70.1-143","DOIUrl":"https://doi.org/10.52526/25792776-23.70.1-143","url":null,"abstract":"A new approach to solving of the Ambartsumian’s functional equation is presented. Its application is illustrated on the two classical cases: a) in the case of a plane-parallel semi-infinite medium with monochromatic anisotropic scattering and b) the simple one-dimensional problem of diffuse reflection of radiation from the scattering-absorbing semi-infinite medium in the case of the general law of redistribution of radiation by frequencies. The desired: a) azimuthal harmonics of reflection function dependent on two angular variables are explicitly expressed through the according eigenfunctions of one angle variable and b) diffuse reflection function of two frequency variables also expressed through a system of according eigenfunctions which have only one frequency variable. This does not require the use of any simplifying assumptions or special decompositions of the characteristics of elementary act of scattering: a) of scattering indicatrix and b) of the redistribution function of radiation by frequencies.","PeriodicalId":412578,"journal":{"name":"Communications of the Byurakan Astrophysical Observatory","volume":"144 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131562862","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"BL Lacertae: dynamics of a quasi-stationary feature in the inner part of a relativistic jet","authors":"L. Hambardzumyan, T. Arshakian, A. Pushkarev","doi":"10.52526/25792776-23.70.1-94","DOIUrl":"https://doi.org/10.52526/25792776-23.70.1-94","url":null,"abstract":"Radio interferometric VLBA observations allow the mapping of relativistic jets with sub-milliarcsecond resolution, which enables the studying of the fine structure and dynamics of the jets in active galactic nuclei. A quasi-stationary component (QSC) near the radio core is observed in a number of blazars. VLBA monitoring of the BL Lacertae object at 15 GHz has shown that the QSC located at about 0.26 mas from the radio core is followed by superluminal components, whose dynamics forms the structure of the jet on parsec scales. We study the trajectory of the QSC using the 164 epochs taken from the MOJAVE (Monitoring Of Jets in Active galactic nuclei with VLBA Experiments) database. The trajectory of the QSC is complex, and we use a moving average smoothing filter to track the intrinsic motion of the QSC. At small time scales of few months, we find that the QSC makes a swinging motion with about 23 reversals over 20 years with an average period of about 0.5 years. The trajectories between the reversals have varying lengths with a mean value of about 30 μas (∼ 0.04 pc) and curvatures of varying degrees. Number of clockwise reversals are about twice less than that of anticlockwise reversals.","PeriodicalId":412578,"journal":{"name":"Communications of the Byurakan Astrophysical Observatory","volume":"174 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128272714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cosmological scalar field Ф CDM models","authors":"O. Avsajanishvili","doi":"10.52526/25792776-23.70.1-106","DOIUrl":"https://doi.org/10.52526/25792776-23.70.1-106","url":null,"abstract":"Cosmological models that go beyond the standard Lambda Cold Dark Matter (ΛCDM) scenario, namely, scalar field ϕCDM models, are considered. The Hubble expansion rate of the universe, the dynamic and the energetic domination of dark energy, the formation of matter density fluctuations and the large-scale structure growth rate in these models compared to the standard spatially-flat ΛCDM model are investigated.","PeriodicalId":412578,"journal":{"name":"Communications of the Byurakan Astrophysical Observatory","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127177031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The essence of onset and self-sustenance of turbulence in astrophysical shear flows Sources","authors":"M. Kavtaradze, G. Mamatsashvili, G. Chagelishvil","doi":"10.52526/25792776-23.70.1-152","DOIUrl":"https://doi.org/10.52526/25792776-23.70.1-152","url":null,"abstract":"To understand the mechanism of the self-sustenance of subcritical turbulence in spectrally stable astrophysical (constant) shear flows, we performed direct numerical simulations of turbulence in plane hydrodynamic and MHD homogeneous shear flows in the local shearing-box approximation with subsequent analysis of the dynamical processes in spectral/Fourier space. In the MHD case, we considered uniform magnetic field directed parallel to the flow. There are no exponentially growing modes in such flows and the turbulence is instead energetically supported only by the linear transient growth of Fourier harmonics of perturbations due to the shear flow non-normality. This non-normality-induced growth, also known as nonmodal growth, is anisotropic in Fourier space, which, in turn, leads to a specific anisotropy of nonlinear processes in this space. As a result, a main nonlinear process in shear flows is transverse (angular) redistribution of harmonics in Fourier space – nonlinear transverse cascade – rather than usual direct or inverse cascades. It is demonstrated that the turbulence is sustained by a subtle interplay between the linear nonmodal growth and the nonlinear transverse cascade for all considered flow configurations. The only energy supplier for the turbulence is the linear transient growth of perturbations due to the flow shear, which is mediated by Reynolds and Maxwell stresses, extracting, respectively, kinetic and magnetic energy from the background flow – the nonlinear processes do not directly change the total perturbation energy but only redistribute it among Fourier harmonics of perturbations. We propose the basic cycles of the turbulence sustenance in the considered cases, which clearly show the synergy of linear and nonlinear processes in the self-organization of the flow. Performing numerical simulations for different values of the background magnetic field, we show that with the increase of the field, the onset of turbulence occurs at larger times and the power of turbulence reduces. Finally, at definite threshold background magnetic field the flow completely stabilizes. It is significant that, there is an essential difference in the energy supply of plane and rotating/Keplerian astrophysical shear flows: in plane shear flows the leading linear process energetically supplying turbulence is due to the kinematics (Reynolds stress), while for Keplerian rotation – is due to magnetic field (Maxwell stress).","PeriodicalId":412578,"journal":{"name":"Communications of the Byurakan Astrophysical Observatory","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128500803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigations of late-type giant stars from the First Byurakan Spectral Sky Survey","authors":"G. Kostandyan, K. Gigoyan, K. Gigoyan","doi":"10.52526/25792776-23.70.1-54","DOIUrl":"https://doi.org/10.52526/25792776-23.70.1-54","url":null,"abstract":"We study late-type giants found in the First Byurakan Survey (FBS) data base. The third Gaia data release (Gaia EDR3) photometric and astrometric data have been used to characterize our sample of 1 100 M-type giants and 130 C-type stars found at high latitudes. Phase dependent light-curves from large sky area variability data bases such as Catalina Sky Survey (CSS) and The light curves from the Catalina Sky Survey (CSS), All-Sky Automated Survey for Supernovae (ASAS-SN) and Transiting Exoplanet Survey Satellite (TESS) databases were exploited to study their variability nature. Using TESS light curves, the variability types of some objects have been established for the first time.","PeriodicalId":412578,"journal":{"name":"Communications of the Byurakan Astrophysical Observatory","volume":"197 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125864069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dependence of standardization parameters of type Ia supernova light curves on redshift","authors":"A. P. Mahtessian, G. Karapetian, M. A. M. A. Hovhannisyan, L. A. Mahtessian","doi":"10.52526/25792776-23.70.1-114","DOIUrl":"https://doi.org/10.52526/25792776-23.70.1-114","url":null,"abstract":"The paper shows that the parameters X1 and C used to standardize the luminosity of type Ia supernovae in the SALT2 model are highly dependent on redshift. This leads to the fact that during standardization, with increasing z, the average absolute stellar magnitude of type Ia supernovae artificially increases and, therefore, for a given apparent magnitude, we attribute to them, on average, a greater distance than they actually have. And therefore, it is believed that they are receding with acceleration. Therefore, such standardization is unsuitable for measuring distances to type Ia supernovae. If the standardization parameter (−αX1 + βC) is replaced by the redshift-dependent parameter (εz), then the parameter ΩΛ turns into 0 in the ΛCDM model.","PeriodicalId":412578,"journal":{"name":"Communications of the Byurakan Astrophysical Observatory","volume":"151 9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131123306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study of the X-ray properties of radio sources, based on NVSS catalogue","authors":"G. Paronyan, A. Mickaelian, H. Abrahamyan, G. Mikayelyan, A. G. Sukiasyan, L. Hambardzumyan, V. K. Mkrtchyan","doi":"10.52526/25792776-23.70.1-88","DOIUrl":"https://doi.org/10.52526/25792776-23.70.1-88","url":null,"abstract":"An identification of radio sources from the NVSS list with ROSAT X-ray sources was made as well as also with optical objects from SDSS DR 16. We have tried to find the connection between the fluxes of different wave ranges, for different types of objects. We also have tried to find the relationship between the sizes and polarization angles of sources with the types of objects and recurrence. The fluxes detected from X-ray, optical, and radio bands for them are compiled. This database allows an investigation on broad band energy distribution and other possible correlations among spectral indices and luminosities for various types of extragalactic objects.","PeriodicalId":412578,"journal":{"name":"Communications of the Byurakan Astrophysical Observatory","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131203414","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spectroscopy of new Herbig-Haro objects discovered in frames of BNBIS","authors":"T. Movsessian, T. Magakyan","doi":"10.52526/25792776-23.70.1-49","DOIUrl":"https://doi.org/10.52526/25792776-23.70.1-49","url":null,"abstract":"We present long-slit spectroscopy of some new Herbig-Haro objects and outflow systems discovered\u0000in the frames of Byurakan Narrow Band Imaging Survey (BNBIS) performed on 1 m Schmidt telescope\u0000of Byurakan Observatory. Spectroscopic observations were carried out with 6 m telescope (Russia) using\u0000SCORPIO2 spectral camera. All selected objects are associated with deeply embedded infrared sources in\u0000the molecular clouds. Long-slit spectroscopy allows to obtain position velocity diagrams of the emission\u0000structures like Herbig-Haro objects. Velocity fields of the outflows from IRAS 06277+1016 infrared source\u0000in Mon R1, from V963 Mon and 2MASS 06084223-0657385 in Mon R2 as well as from IRAS 06212-1049\u0000are presented. Our spectroscopic data revealed bipolar outflow nature of the outflows associated with\u00002MASS 06084223-0657385 and IRAS 06212-1049.","PeriodicalId":412578,"journal":{"name":"Communications of the Byurakan Astrophysical Observatory","volume":"64 10","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114057601","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evolutionary stages of the universe","authors":"R. Natsvlishvili","doi":"10.52526/25792776-23.70.1-123","DOIUrl":"https://doi.org/10.52526/25792776-23.70.1-123","url":null,"abstract":"The matter from which the Metagalaxy is formed is constantly changing, evolving. Since the speed of propagation of the electromagnetic wave in space is not instantaneous, it is limited, within the capabilities of existing powerful telescopes, we can observe the forms of matter in different stages of the evolution of the Metagalaxy in chronological order. So, the more distant the form of matter in the Metagalaxy, the earlier, or younger, it is. In this article, we tried to characterize the stages of the Metagalaxy evolution from a dynamic point of view. In the case of such a model of the Universe, quasars are objects of earlier stage of the evolution of galaxies, and blazars are objects of an intermediate stage between quasars and galaxies.","PeriodicalId":412578,"journal":{"name":"Communications of the Byurakan Astrophysical Observatory","volume":"7 5","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132806182","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}