Astronomy Letters-A Journal of Astronomy and Space Astrophysics最新文献_第3页

Highly Variable Active Galactic Nuclei in the SRG/eROSITA Sky Survey: II. Spectroscopic Identification of Sources with Russian Telescopes SRG/eROSITA巡天中高度可变的活动星系核：II。用俄罗斯望远镜对光源进行光谱识别

IF 0.8 4区物理与天体物理

Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2025-06-27 DOI: 10.1134/S1063773725700082

G. A. Khorunzhev, S. Yu. Sazonov, P. S. Medvedev, M. R. Gilfanov, A. V. Dodin, A. V. Moiseev, I. A. Zaznobin, A. V. Moskaleva, D. V. Oparin, M. A. Burlak, O. V. Vozyakova, M. V. Eselevich, R. A. Sunyaev

{"title":"Highly Variable Active Galactic Nuclei in the SRG/eROSITA Sky Survey: II. Spectroscopic Identification of Sources with Russian Telescopes","authors":"G. A. Khorunzhev, S. Yu. Sazonov, P. S. Medvedev, M. R. Gilfanov, A. V. Dodin, A. V. Moiseev, I. A. Zaznobin, A. V. Moskaleva, D. V. Oparin, M. A. Burlak, O. V. Vozyakova, M. V. Eselevich, R. A. Sunyaev","doi":"10.1134/S1063773725700082","DOIUrl":"10.1134/S1063773725700082","url":null,"abstract":"We present the results of our spectroscopic identification of nine highly variable X-ray sources detected by the eROSITA telescope of the SRG observatory during its all-sky survey and published in the first paper of this series (the complete sample consists of 49 objects; Medvedev et al. 2022). For our observations we used the BTA, SAI25, AZT-33IK, and RTT-150 telescopes. One of the objects has turned out to be a cataclysmic variable, and another one has already been known previously as a tidal disruption event. The remaining seven objects have turned out to be active galactic nuclei (AGNs) at redshifts from 0.035 to 0.523. For four objects we have estimated the mass of the central black hole from the width and luminosity of the broad H(alpha) line component. These black holes have turned out to be moderately massive: from ({sim}8times 10^{6}) to ({sim}10^{8})\u0000 (M_{odot}).","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"50 12","pages":"744 - 755"},"PeriodicalIF":0.8,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145145191","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}

引用次数: 0

850 SRG/eROSITA Sources in the Pleiades 850srg /eROSITA来源在昴宿星

IF 0.8 4区物理与天体物理

Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2025-06-27 DOI: 10.1134/S1063773725700094

I. M. Khamitov, I. F. Bikmaev, M. R. Gilfanov, R. A. Sunyaev, P. S. Medvedev

{"title":"850 SRG/eROSITA Sources in the Pleiades","authors":"I. M. Khamitov, I. F. Bikmaev, M. R. Gilfanov, R. A. Sunyaev, P. S. Medvedev","doi":"10.1134/S1063773725700094","DOIUrl":"10.1134/S1063773725700094","url":null,"abstract":"Using SRG/eROSITA X-ray sky survey data and the optical catalog of 2209 Pleiades cluster members constructed from Gaia data, we have found 850 X-ray sources associated with cluster stars. More than 650 of them have been detected in X-rays for the first time. At the distance of the Pleiades the nominal sensitivity of eROSITA in this sky region corresponds to a (0.3{-}2.3) keV luminosity (L_{X}sim 1.6times 10^{28}) erg s({}^{-1}). The eROSITA sources associated with the Pleiades radiate with a total luminosity (L_{X,textrm{total}}sim 1.3times 10^{32}) erg s({}^{-1}), which exceeds the X-ray luminosity of the quiet Sun by a million times. A strong, more than a factor of 10, X-ray variability has been recorded for 27 sources. Most of them are known as eruptive optical variable dM stars. (R_{X}=log(L_{X}/L_{textrm{bol}})) for Pleiades stars increases with decreasing effective stellar temperature from (R_{X}approx{-}5) to (R_{X}approx{-}2). The (R_{X}) distribution of stars is bimodal. The left peak at (R_{X}sim{-}4.3) is formed by FGK stars, while the right peak at (R_{X}sim{-}3.1) is mostly populated by M stars. The dependence of (R_{X}) on the Rossby number (Ro) is different for different spectral types. At small Rossby numbers for K and M stars (R_{X}sim{-}3) and depends weakly on (Ro). At (Rogtrsim 0.25) a rapid decrease in (R_{X}) is observed for K stars, while there are no M stars with large Rossby numbers in our sample. Most of the F and G stars lie in the range of lower values, (R_{X}sim{-}4.5), but the size of our sample is not enough to characterize in more detail the (R_{X}{-}Ro) relation for them.","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"50 12","pages":"780 - 795"},"PeriodicalIF":0.8,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145145189","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}

引用次数: 0

An X-ray and Optical Study of the Dwarf Nova Candidate OGLE-BLG-DN-0064 矮新星候选星OGLE-BLG-DN-0064的x射线和光学研究

IF 1.1 4区物理与天体物理

Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2025-03-25 DOI: 10.1134/S1063773725700033

A. B. Sibgatullin, V. I. Dodon, I. I. Galiullin, A. I. Kolbin, V. V. Shimansky, A. S. Vinokurov

{"title":"An X-ray and Optical Study of the Dwarf Nova Candidate OGLE-BLG-DN-0064","authors":"A. B. Sibgatullin, V. I. Dodon, I. I. Galiullin, A. I. Kolbin, V. V. Shimansky, A. S. Vinokurov","doi":"10.1134/S1063773725700033","DOIUrl":"10.1134/S1063773725700033","url":null,"abstract":"The source OGLE-BLG-DN-0064 (hereafter OGLE64) was classified as a potential dwarf nova based on its regular outburst activity revealed by the OGLE optical survey. In this paper we investigate the X-ray and optical emissions from the source OGLE64 based on archival Chandra and Swift X-ray data and our optical observations with the 6-m BTA telescope at the Special Astrophysical Observatory of the Russian Academy of Sciences. OGLE64 shows an X-ray luminosity (L_{X}approx 1.6times 10^{32}) erg s({}^{-1}) and a high X-ray-to-optical flux ratio (F_{X}/F_{textrm{opt}}approx 1.5) typical for accreting white dwarfs. The X-ray spectrum of OGLE64 is better fitted by the models of a power law with a photon index (Gammaapprox 1.9) and an optically thin plasma with a temperature (kTapprox 6.4) keV. The optical spectrum shows hydrogen and neutral helium emission lines in some of which a double-peaked structure is observed. An analysis of the outburst activity of OGLE64 based on data from the OGLE, ZTF, ATLAS, and ASAS-SN optical surveys has revealed superoutbursts with a characteristic supercycle (P_{textrm{super}}approx 400) days. We found no significant variability in either the X-ray or optical light curves of OGLE64 that could be associated with the change in the visibility conditions for the emitting regions at different orbital phases. Our estimates of the orbital period of the system by indirect methods show that the period probably lies in the range (P_{textrm{orb}}sim 1.5{-}3.5) h. The properties of the X-ray and optical emissions from OGLE64 lead us to conclude that the system is an SU UMa-type dwarf nova.","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"50 11","pages":"676 - 686"},"PeriodicalIF":1.1,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143688620","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}

引用次数: 0

Gaia 19cwm—An Eclipsing Dwarf Nova of WZ Sge Type with a Magnetic White Dwarf 盖亚19cwm - WZ Sge型食矮星新星与一颗磁性白矮星

IF 1.1 4区物理与天体物理

Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2025-03-25 DOI: 10.1134/S1063773725700057

A. I. Kolbin, T. A. Fatkhullin, E. P. Pavlenko, M. V. Suslikov, V. Yu. Kochkina, N. V. Borisov, A. S. Vinokurov, A. A. Sosnovskij, S. S. Panarin

{"title":"Gaia 19cwm—An Eclipsing Dwarf Nova of WZ Sge Type with a Magnetic White Dwarf","authors":"A. I. Kolbin, T. A. Fatkhullin, E. P. Pavlenko, M. V. Suslikov, V. Yu. Kochkina, N. V. Borisov, A. S. Vinokurov, A. A. Sosnovskij, S. S. Panarin","doi":"10.1134/S1063773725700057","DOIUrl":"10.1134/S1063773725700057","url":null,"abstract":"The spectral and photometric studies of the cataclysmic variable Gaia 19cwm (or ZTF19aamkwxk) have been performed. Based on the analysis of long-term variability, it is concluded that the object belongs to WZ Sge type stars. The light curves show eclipses recurring with an orbital period of (86.32048pm 0.00005) min, as well as an out-of-eclipse variability with a period of ({approx}6.45) min. The latter period is stable for ({sim}4) years and appears to correspond to the rotation of a magnetic white dwarf, i.e., Gaia 19cwm is an intermediate polar. The Gaia 19cwm spectra show photospheric lines of the white dwarf, and Doppler tomograms demonstrate the presence of an accretion disk and a hot spot. Analysis of the eclipse light curve gives an estimates of the white dwarf mass (M_{1}=0.66pm 0.06)\u0000 (M_{odot}), the donor mass (M_{2}=0.073pm 0.015)\u0000 (M_{odot}), and the orbital inclination (i=83.8^{circ}pm 1.1^{circ}). Modeling of the spectral energy distribution gives the white dwarf temperature of (T_{textrm{eff}}approx 13,000) K. The X-ray luminosity (L_{X}=(1.6pm 0.3)times 10^{31}) erg/s allows to assign Gaia 19cwm to a small group of low-luminosity intermediate polars.","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"50 11","pages":"687 - 699"},"PeriodicalIF":1.1,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143688598","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}

引用次数: 0

PISN 2018ibb: Radioactive Emission of [O III] Lines PISN 2018ibb: [O III]谱线的放射性发射

IF 1.1 4区物理与天体物理

Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2025-03-25 DOI: 10.1134/S106377372570001X

N. N. Chugai

引用次数: 0

Low-Energy Neutrino Emission from Primordial Black Holes: A New Possibility of Observing Hawking Radiation 原始黑洞的低能中微子发射：观测霍金辐射的一种新可能性

IF 1.1 4区物理与天体物理

Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2025-03-25 DOI: 10.1134/S1063773725700021

Yu. A. Lysyy, P. A. Kislitsyn, A. V. Ivanchik

{"title":"Low-Energy Neutrino Emission from Primordial Black Holes: A New Possibility of Observing Hawking Radiation","authors":"Yu. A. Lysyy, P. A. Kislitsyn, A. V. Ivanchik","doi":"10.1134/S1063773725700021","DOIUrl":"10.1134/S1063773725700021","url":null,"abstract":"The study of primordial black holes (PBHs) and the Hawking radiation that they can generate is an important step in understanding the role of these phenomena in the cosmological evolution of the Universe. PBHs can be part of the dark matter, the seeds of supermassive black holes, and the sources of Hawking radiation, which, in contrast to the radiation from other black holes, can be observable. At the same time, under conditions of the evolution of the Universe from the Big Bang to the present day, PBHs lose most of their mass in the form of neutrino emission. This is because for black holes with (M<10^{23}) g, apart from the emission of massless particles, the emission of the lightest massive particle, the neutrino, is added. Moreover, this emission turns out to be dominant, and since only black holes with masses ({lesssim}10^{15}) g have evaporated significantly by the present time ((t_{0}=13.8) Gyr), the neutrino component dominates in the overall emission spectrum of PBHs. In this paper we present new estimates of the spectra of neutrinos emitted by PBHs of various masses, focusing attention on the low-energy ((mathbf{E}_{textrm{kin}}in[0.01{-}1]) eV) emission for the first time. As a result of our calculations, we have shown that black holes in the range of masses ([10^{9}{-}10^{11}]) g emit neutrinos with an intensity exceeding the background fluxes from known astrophysical sources in the low-energy range, while in the high-energy range the emission will be under the background without coming into conflict with observational constraints. These results open up new opportunities for the potential observation of emission from PBHs and can stimulate the development of neutrino detection technologies in the low-energy range. The observation of neutrinos in this range is one of the few possibilities to confirm the existence of Hawking radiation.","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"50 11","pages":"649 - 656"},"PeriodicalIF":1.1,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143688621","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}

引用次数: 0

Extragalactic Radio Sources with Large Changes in Their Apparent Coordinates 视坐标大变化的河外射电源

IF 1.1 4区物理与天体物理

Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2025-03-25 DOI: 10.1134/S1063773725700045

A. A. Osetrova, O. A. Titov, A. E. Melnikov

引用次数: 0

Production of Positrons in the Galactic Center by Subrelativistic Protons and Nuclei 次相对论性质子和原子核在银河系中心产生正电子

IF 1.1 4区物理与天体物理

Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2025-02-28 DOI: 10.1134/S1063773724700464

D. O. Chernyshov, V. A. Dogiel, I. M. Dremin, A. M. Kiselev, A. V. Kopyev

{"title":"Production of Positrons in the Galactic Center by Subrelativistic Protons and Nuclei","authors":"D. O. Chernyshov, V. A. Dogiel, I. M. Dremin, A. M. Kiselev, A. V. Kopyev","doi":"10.1134/S1063773724700464","DOIUrl":"10.1134/S1063773724700464","url":null,"abstract":"We propose alternative processes of generation of positrons producing 511 keV annihilation line in the Galactic bulge by cosmic rays. Since relativistic cosmic rays produce both positrons and gamma rays and the flux of the latter is limited by observations, we consider sub-relativistic particles. Particles with energies below the threshold of charged pions production can generate positrons in two processes: direct pair production in electromagnetic interactions (ultraperipheral collisions) and by production of unstable isotopes by spallation and proton capture. Cross-sections of these processes are very small at non-relativistic energies and rapidly increase with particles velocities. Optimal protons velocities are about (0.1{-}0.3) of luminal velocity. In this velocity range, the cross-sections are high enough while gamma rays production is low. Thus, to produce positrons a special class of cosmic ray sources is necessary. These sources should produce large amount of sub-relativistic particles in the specified velocity range. We consider fast blue optical transients and stellar tidal disruptions by central black hole as these type of sources. Characteristic outflow velocities in these objects are of order of tenth of luminal velocity. If acceleration of relativistic particles in these outflows is low enough, they can produce the required amount of positrons. We also show that energy produced by stellar tidal disruptions events is large enough to produce the required amount of positrons.","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"50 10","pages":"593 - 599"},"PeriodicalIF":1.1,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143521752","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}

引用次数: 0

Evolution of the Orbital Period of the Ultracompact Binary System ZTF J213056.71+442046.5 超紧凑双星系统ZTF J213056.71+442046.5的轨道周期演化

IF 1.1 4区物理与天体物理

Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2025-02-28 DOI: 10.1134/S1063773724700543

S. V. Antipin, L. N. Berdnikov, K. A. Postnov, A. M. Zubareva, N. P. Ikonnikova, M. A. Burlak, A. A. Belinski

引用次数: 0

Measuring the Magnetic Field Strength of a Transient X-ray Pulsar 4U 1901+03 by Its Variability on Different Time Scales 瞬变x射线脉冲星4U 1901+03磁场强度在不同时间尺度上的变化测量

IF 1.1 4区物理与天体物理

Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2025-02-28 DOI: 10.1134/S1063773724700506

I. A. Mereminskiy, A. N. Semena, A. A. Lutovinov, S. S. Tsygankov, S. V. Molkov, D. I. Karasev

{"title":"Measuring the Magnetic Field Strength of a Transient X-ray Pulsar 4U 1901+03 by Its Variability on Different Time Scales","authors":"I. A. Mereminskiy, A. N. Semena, A. A. Lutovinov, S. S. Tsygankov, S. V. Molkov, D. I. Karasev","doi":"10.1134/S1063773724700506","DOIUrl":"10.1134/S1063773724700506","url":null,"abstract":"By combining data from several X-ray telescopes (Swift/XRT, NICER, Chandra) we reconstructed a profile of the 2019 outburst of accreting X-ray pulsar 4U 1901+03 from its peak down to the return to the ‘‘low’’ state. Softening of the X-ray spectrum and disappearance of the pulsations at a later stages of the outburst tentatively indicates that the source transitioned to the ‘‘propeller’’ state at luminosity about (10^{36}) erg s({}^{-1}), which corresponds to a magnetic field strength of (Blesssim 10^{12}) G at the neutron star surface. We also investigated the fast X-ray variability that was observed during the peak of 2003 outburst. The shape of the power spectrum could be described with a broken power law, with a break frequency of 7.5 Hz. Assuming that this frequency corresponds to a viscous frequency at a magnetospheric boundary we estimated magnetic field strength as (Bapprox 7times 10^{11}) G, which is similar to the estimate obtained from observed transition to the ‘‘propeller’’ regime.","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"50 10","pages":"600 - 607"},"PeriodicalIF":1.1,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143521702","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}

引用次数: 0