Astrophysics最新文献

{"title":"Plane Symmetric String Cosmological Model with Zero Mass Scalar Field in f (R) Gravity","authors":"Kalpana Pawar,&nbsp;A. K. Dabre,&nbsp;Pallavi Makode","doi":"10.1007/s10511-023-09796-w","DOIUrl":"10.1007/s10511-023-09796-w","url":null,"abstract":"<div><div><p>In this article, an anisotropic Locally Rotationally Symmetric (LRS) Bianchi type I metric in the presence of cloud string fluid and zero mass scalar field in reference to <i>f</i> (<i>R</i>) gravity have been investigated. To obtain the deterministic solutions we assumed the weak field limit for a point-like source <i>f</i> (<i>R</i>) = <i>R</i>^3/2 and the very well-known expansion-shear scalar proportionality relation. Furthermore, some physical and kinematical parameters have been calculated to study the astrophysical consequences of obtained model, which shows a good resemblance to the recent observational data.</p></div></div>","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41087373","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Поверхностная фотометрия 50 карликовых галактик в местном объеме","authors":"К. А. Крыжановский, М. Е. Шарина, Игорь Дмитриевич Караченцев, Г. М. Каратаева","doi":"10.54503/0571-7132-2023.66.3-317","DOIUrl":"https://doi.org/10.54503/0571-7132-2023.66.3-317","url":null,"abstract":"Представлены результаты поверхностной фотометрии 50-ти галактик в Местном объеме на основе архивных изображений, полученных на космическом телескопе Хаббла. Для выборки галактик приводятся интегральные величины в полосах V и I, а также профили яркости и цвета. Проведено сравнение полученных фотометрических параметров с измерениями других авторов.\u0000The results of surface photometry of 50 galaxies in the Local Volume based on archival images obtained with the Hubble Space Telescope are presented. For the sample of galaxies, the integrated magnitudes in the V and I bands are given, as well as the brightness and color profiles. The obtained photometric parameters are compared with the measurements of other authors.","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74955448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Активность молодой звезды EPIC 204376071 из ассоциации Upper Sco","authors":"И. С. Саванов","doi":"10.54503/0571-7132-2023.66.3-373","DOIUrl":"https://doi.org/10.54503/0571-7132-2023.66.3-373","url":null,"abstract":"По наблюдениям миссии К2 космического телескопа Кеплер выполнено исследование активности EPIC 204376071-молодого объекта, члена ассоциации Upper Sco с возрастом 11±3 млн лет, кривая блеска которого обладает единичным затмением суточной продолжительности с глубиной около 80%. EPIC 204376071 является маломассивным М-карликом с массой 0.16 M . По наблюдениям кампании С15 миссии К2 мы уточнили период вращения и амплитуду переменности блеска звезды, а также по стандартной методике оценили величину параметра запятненности A в абсолютной мере. Величина периода вращения звезды Р равна 1.6270 ±0.030 сут. Площадь пятен на поверхности EPIC 204376071 превосходит максимальную площадь пятен на Солнце и составляет величину порядка 7900 м.д.п. Представлены результаты восстановления температурных неоднородностей на поверхности EPIC 204376071. На построенной карте хорошо различимы две холодные области, разделенные по долготе примерно на 150o. Для оценки свойств вспышечной активности EPIC 204376071 была рассмотрена одна наиболее достоверная вспышка с амплитудой блеска около 4%.\u0000Using the observations of the K2 mission of the Kepler Space Telescope we studied the activity of EPIC 204376071 - a young object in the Upper Sco association with the age of 11 ± 3 million years, whose light curve has a single occultation of daily duration with a depth of about 80%. EPIC 204376071 is a M-dwarf of mass 0.16  M . On the base on the observations of the C15 campaign of the K2 mission we estimated the rotation period, amplitude of the variability of the brightness of the star and the spottedness parameter A in absolute measure using the standard method. The magnitude of the rotation period of the star P is 1.6270 ± 0.030 days. The area of spots on the surface of EPIC 204376071 exceeds the maximum area of spots on the Sun and is about 7900 MSH. The results of the restoration of temperature inhomogeneities on the surface of EPIC 204376071 are presented. Two cool regions separated in longitude by about 150o are clearly distinguishable on the constructed map. Characteristics stellar flare activity are estimated on the base of one of the most reliable flare. The flare amplitude is about 4%. The measured relative energy RE of the flare was 212 sec. The calculated energy of the flare Efl equal to 1.1·1034 erg (logEfl = 34.05). The corresponding probable value of the coronal mass ejection can reach 4.1·1020 g. Possible explanations of a single occultation of 1-day duration with a depth of about 80% on the EPIC 204376071 light curve are discussed.","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85494454","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Движение частицы в поле бесконечного плоского слоя","authors":"Р. М. Авакян, А. А. Саарян, С. С. Джибилян","doi":"10.54503/0571-7132-2023.66.3-441","DOIUrl":"https://doi.org/10.54503/0571-7132-2023.66.3-441","url":null,"abstract":"В настоящей работе в рамках общей теории относительности исследуется движение светового сигнала и пробной частицы в поле бесконечного плоского слоя. Рассмотрены оба случая внешнего решения для гравитационного поля в вакууме, соответствующие метрикам Риндлера и Тауба. Определяются время движения и путь, пройденный частицей до ее остановки. Показано, что в геометрии Тауба, в отличие от светового сигнала, материальная частица не достигает сингулярности. Определено минимальное расстояние от сингулярности в зависимости от энергии частицы. Для сравнения приводятся результаты в рамках специальной теории относительности.\u0000In this paper we investigate the motion of a light signal and a test particle in the field of an infinite flat slab within the framework of the general relativity. Both cases of the external solution for the gravitational field in the vacuum, corresponding to the Rindler and Taub metrics, are considered. The time of motion and the path traveled by the particle before it stops are determined. It is shown that in the Taub geometry, in contrast to the light signal, a material particle does not reach a singularity. The minimum distance from the singularity is determined depending on the energy of the particle. For comparison, results are given within the framework of the special relativity.","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84644040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Environmental Dependence of Different Colors of Active Galactic Nucleus (AGN) Host Galaxies","authors":"Xin-Fa Deng,&nbsp;Zhi-Yong Wu","doi":"10.1007/s10511-023-09790-2","DOIUrl":"10.1007/s10511-023-09790-2","url":null,"abstract":"<div><div><p>Using the apparent-magnitude limited active galactic nucleus (AGN) host galaxy sample of the Sloan Digital Sky Survey Data Release 12 (SDSS DR12), we investigate the environmental dependence of the u-r, u-g, g-r, r-i and i-z colors of AGN host galaxies. We divide the whole apparent-magnitude limited AGN sample into many subsamples with a redshift binning size of ?z = 0.01, and analyze the environmental dependence of all five galaxy colors of subsamples in each redshift bin. It turns out that overall, all five galaxy colors of AGN host galaxies are weakly correlated with the local environment.</p></div></div>","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4113374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Correction to: Accelerating Kaluza-Klein Universe in Modified Theory of Gravitation","authors":"S. D. Katore,&nbsp;S. P. Hatkar,&nbsp;D. P. Tadas","doi":"10.1007/s10511-023-09789-9","DOIUrl":"10.1007/s10511-023-09789-9","url":null,"abstract":"","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4008285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the Unified Scheme of γ-Ray Emitting Jetted Active Galactic Nuclei","authors":"A. I. Audu,&nbsp;F. C. Odo,&nbsp;E. U. Iyida,&nbsp;O. Okike,&nbsp;A. A. Ubachukwu","doi":"10.1007/s10511-023-09779-x","DOIUrl":"10.1007/s10511-023-09779-x","url":null,"abstract":"<div><div><p>The discovery of γ - ray emitting Seyfert galaxies has opened a new unified scheme of active galactic nuclei (AGN) in which jetted Seyfert galaxies are viewed as young counterparts of radio loud AGN. In this paper, we investigate the relationship between gamma-ray (γ - ray) properties of jetted Seyfert galaxies and those of traditionally radio galaxies, radio quasars and BL Lac objects. Results show that jetted Seyfert galaxies appear as low luminosity tail of the radio loud AGNs on the luminosity redshift (L_γ – z) plane, indicating an evolutionary link between them. Nevertheless, narrow-line Seyfert galaxies (NLS1s) do not share similar characteristics with Seyfert galaxies as they possess higher luminosities and redshift than Seyfert galaxies, suggestive that NLS1s are more evolved sources. Analyses of γ – ray and radio core-dominance show that for each subclass of jetted AGN, the beaming angle is wider for radio than for γ - ray emissions. While Seyferts and radio galaxies, on average, have similar low inclination to the line of sight, NLS1 objects have orientations similar to quasars and BL Lacs. There is a significant correlation (r ~ 0.7) between the γ - ray core dominance and γ - ray luminosity. The results are consistent with the revised unification scheme and suggests that NLS1s are highly beamed sources whose parent populations can be found among the regular Seyferts and/or radio galaxies</p></div></div>","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5179642","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the Centenary of L. V. Mirzoyan","authors":"","doi":"10.1007/s10511-023-09778-y","DOIUrl":"10.1007/s10511-023-09778-y","url":null,"abstract":"","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5177299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Large-Scale Electric Currents in Coronal Heating Processes above Active Regions on the Sun","authors":"Yu.A. Fursyak","doi":"10.1007/s10511-023-09786-y","DOIUrl":"10.1007/s10511-023-09786-y","url":null,"abstract":"<div><div><p>This paper poses the problem of studying the role of large-scale electric currents propagating in the upper layers of the solar atmosphere in processes of coronal heating of the sun. For detecting and calculating the magnitude of the large-scale electric current, data on the distribution of the components of the magnetic field vector in the photosphere provided by the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO) were used. Photoheliograms of the sun’s corona in the ultraviolet radiation channels at 131, 171, 193, and 211 Å provided by the Atmospheric Imaging Assembly (AIA/SDO) were used to estimate the temperature in the corona above active regions (ARs). The dynamics of the large-scale current and the average temperature in 9 regions with different levels of flare activity of the corona above the ARs have been studied and charts of the spatial distribution of the temperature in the corona above the ARs have been constructed. The following results have been obtained: 1. Heating of the coronal matter owing to ohmic dissipation of large-scale electric currents proceeds in a stationary regime. 2. The increase in the average temperature in the corona above an AR during solar flares to <span>(&lt;overline{mathrm{log}T }&gt;=6.3-6.5)</span> (2.0-3.2 MK) is caused, not only by heating of coronal structures by large-scale electric currents, but also by other processes at coronal elevations. 3. For the NOAA 11899 and 12494 regions a reduction in the average temperature of the corona to <span>(&lt;overline{mathrm{log}T }&gt;=5.7)</span> (0.5-0.6 MK) was observed with a simultaneous drop in the values of the large-scale electric current to zero. These observations indicate that the mechanism for heating of the corona by ohmic dissipation of electric currents is shut off at zero values (within the computational errors) of the large-scale electric current. 4. In the NOAA regions 12192 and 12371, when constructing charts of the temperature distribution in the corona outside flare events, hot structures with temperatures ≥ 10 MK were observed outside the flare events which appear to mark the location of the channel of a large-scale electric current at coronal elevations. For the NOAA region 12192 this assumption is confirmed by a numerical simulation carried out in 2016.</p></div></div>","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5178554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multiwavelength Properties of Selected High Redshift Blazars","authors":"G. Harutyunyan","doi":"10.1007/s10511-023-09780-4","DOIUrl":"10.1007/s10511-023-09780-4","url":null,"abstract":"<div><div><p>High-redshift blazars detected in the γ -ray band are the most powerful steady objects in the universe. Multiwavelength observations of these distant objects are of particular interest as they can help to understand the γ -ray evolution of blazars as well as the formation and propagation of relativistic jets in the early epochs of the Universe. In this study, we investigate the origin of broadband emission from 7 blazars with redshifts greater than 2.5 by analyzing the data accumulated with Swift UVOT/XRT and Fermi-LAT. We observe several flaring periods with significant increases in flux and hardening of the photon index in the high-energy γ -ray band for PKS 1830-211 (z = 2.507), LQAC 247-061 (z = 2.578), TXS 0536+145 (z = 2.690), and 4C+41.32 (z = 2.550). PKS 1830-211 was in an extraordinarily bright state on MJD 58596.49 when the 3-day averaged flux increased up to (1.74 ± 0.04)·10^–5 photon cm^-2 s^-1. The X-ray emission of PKS 1830-211 is also strongly variable and is characterized by a hard photon index in the range of 0.34-0.94. To model the time-averaged broadband spectral energy distribution of the considered sources, we used a one-zone leptonic emission mechanism for the inverse Compton scattering, considering both synchrotron and external photons. We estimated the corresponding parameters of the emitting particles as well as the energetics of the jet.</p></div></div>","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5179649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}