DOCSLIB.ORG

Centaurus a at Hard X-Rays and Gamma Rays

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Centaurus a at Hard X-Rays and Gamma Rays Centaurus A at Hard X-Rays and Soft Gamma-Rays Chandra 1-10 keV CGRO-COMPTEL 1 ± 30 MeV Fermi 100 MeV ± 100 GeV Helmut Steinle Max-Planck-Institut für extraterrestrische Physik Garching, Germany ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- The Many Faces of Centaurus A ± Sydney, 28 June ± 3 July 2009; H. Steinle, MPE 1 / 35 Centaurus A at Hard X-Rays and Soft Gamma-Rays Contents · Introduction · The Spectral Energy Distribution · Properties of the existing measurements in the hard X-ray / soft Gamma-ray regime · Important satellites for this energy / frequency range · Variability of the X-ray / Gamma-ray emission · Two examples of models for the Cen A Spectral Energy Distribution · Problems (features) to be considered when using the hard X-ray / soft Gamma-ray data ± the ªsoft X-ray transient problemº ± the ªSED problemº · Outlook ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- The Many Faces of Centaurus A ± Sydney, 28 June ± 3 July 2009; H. Steinle, MPE 2 / 35 Centaurus A at Hard X-Rays and Soft Gamma-Rays ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Introduction In the introductory (ªsetting the stageº) section of the conference, the talks will cover all frequency ranges in which Centaurus A has been observed. The topic of this talk is the hard X-ray / soft Gamma-ray range, where the Spectral Energy Distribution (SED) shows a maximum, that in most models is contributed to the inverse Compton scattering of synchrotron photons or ambient photons. ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- The Many Faces of Centaurus A ± Sydney, 28 June ± 3 July 2009; H. Steinle, MPE 3 / 35 Centaurus A at Hard X-Rays and Soft Gamma-Rays ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- The Spectral Energy Distribution ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- The Many Faces of Centaurus A ± Sydney, 28 June ± 3 July 2009; H. Steinle, MPE 4 / 35 Centaurus A at Hard X-Rays and Soft Gamma-Rays ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- The Spectral Energy Distribution hard X-rays / soft Gamma-rays ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- The Many Faces of Centaurus A ± Sydney, 28 June ± 3 July 2009; H. Steinle, MPE 5 / 35 Centaurus A at Hard X-Rays and Soft Gamma-Rays ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- The Spectral Energy Distribution CGRO 50 keV 10 GeV ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- The Many Faces of Centaurus A ± Sydney, 28 June ± 3 July 2009; H. Steinle, MPE 6 / 35 Centaurus A at Hard X-Rays and Soft Gamma-Rays ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Properties of the Existing Measurements in the Hard X-ray / Soft Gamma-Ray Regime In the following existing measurements in the hard X-ray (10 ± 500 keV; 1018 ± 1020 Hz) and soft Gamma-ray (500 keV ± 10 GeV; 1020 ± 1024 Hz) energy / frequency range will be discussed. ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- The Many Faces of Centaurus A ± Sydney, 28 June ± 3 July 2009; H. Steinle, MPE 7 / 35 Centaurus A at Hard X-Rays and Soft Gamma-Rays ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- · This frequency range is, compared to adjacent frequency ranges, poorly sampled and due to the lack of sensitive second / third generation detectors (on satellites), the spatial and temporal resolution is not at all comparable to other frequency regimes. · The lack of new detectors is due to the fact, that the interaction probability of radiation with matter in this energy range has a minimum and thus detectors with high sensitivity and good spatial resolution are extremely difficult and costly to build as they have to be very massive and due to the absorption of Gamma-rays in the Earth atmosphere, they have to be operated in space. ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- The Many Faces of Centaurus A ± Sydney, 28 June ± 3 July 2009; H. Steinle, MPE 8 / 35 Centaurus A at Hard X-Rays and Soft Gamma-Rays ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Comparison of the Sensitivity of Various X-ray and Gamma-ray Detectors Very few detectors exist(ed) in the 100 keV to 1 GeV range: · Sigma/Granat (1989 ± 1997) 30 keV ± 1.5 MeV · CGRO (1991 ± 2000) - BATSE 30 keV ± 1 MeV - OSSE 50 keV ± 10 MeV - COMPTEL 750 keV ± 30 MeV - EGRET 50 MeV ± 10 GeV · Integral / IBIS (2002 - ¼.) 15 keV ± ~ 1 MeV · Fermi (2008 - ¼.) (Ch. Dermer, ESA SP-382, 405-412, 1997; Fig. 1a mod.) 10 keV - >300 GeV ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- The Many Faces of Centaurus A ± Sydney, 28 June ± 3 July 2009; H. Steinle, MPE 9 / 35 Centaurus A at Hard X-Rays and Soft Gamma-Rays ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- The low sensitivity of the instruments results in long integration times. Although measurements can be simultaneous, the hard X-ray and Gamma-ray measurements are always orders of magnitude longer in duration than the other simultaneous observations. The detections shown often required integration times of weeks or the combination of whole observation periods of several weeks duration especially during the low emission state of Cen A which prevailed most of the time during the lifetime of Compton Gamma-ray Observatory (CGRO). The combined observation periods were most of the time separated by several weeks or months. ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- The Many Faces of Centaurus A ± Sydney, 28 June ± 3 July 2009; H. Steinle, MPE 10 / 35 Centaurus A at Hard X-Rays and Soft Gamma-Rays ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Comparison of the Imaging Resolution of Various X-ray and Gamma-ray Detectors Only detectors with almost no spatial resolution exist(ed) in the 100 keV to 1 GeV range: · Sigma/Granat (1989 ± 1997) 1° 1 15º on-axis · (1991 ± 2000) CGRO 1Â - BATSE ~ 1° (known sources) - OSSE 1ÂÂ 4° x 12° - COMPTEL 2° - 4° for strong sources - EGRET ~ 0.5° (@ several 100 MeV) · Integral / IBIS (2002 - ¼.) 12' (1' location) · Fermi (2008 - ¼.) Ch. Dermer, ESA SP-382, 405-412, 1997; Fig. 1b mod. 30º ± 5' ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- The Many Faces of Centaurus A ± Sydney, 28 June ± 3 July 2009; H. Steinle, MPE 11 / 35 Centaurus A at Hard X-Rays and Soft Gamma-Rays ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Important Satellites for this Energy / Frequency Range (real photograph) (artists impression) (artists impression) CGRO Integral Fermi 30 keV ± 10 GeV 3 keV ± 10 MeV 10 keV ± > 300 GeV 1999 - 2000 2002 ± (active) 2008 ± (active) ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- The Many Faces of Centaurus A ± Sydney, 28 June ± 3 July 2009; H. Steinle, MPE 12 / 35 Centaurus A at Hard X-Rays and Soft
Load more

Recommended publications
  • AAS Worldwide Telescope: Seamless, Cross-Platform Data Visualization Engine for Astronomy Research, Education, and Democratizing Data
    AAS WorldWide Telescope: Seamless, Cross-Platform Data Visualization Engine for Astronomy Research, Education, and Democratizing Data The Harvard community has made this article openly available. Please share how this access benefits you. Your story matters Citation Rosenfield, Philip, Jonathan Fay, Ronald K Gilchrist, Chenzhou Cui, A. David Weigel, Thomas Robitaille, Oderah Justin Otor, and Alyssa Goodman. 2018. AAS WorldWide Telescope: Seamless, Cross-Platform Data Visualization Engine for Astronomy Research, Education, and Democratizing Data. The Astrophysical Journal: Supplement Series 236, no. 1. Published Version https://iopscience-iop-org.ezp-prod1.hul.harvard.edu/ article/10.3847/1538-4365/aab776 Citable link http://nrs.harvard.edu/urn-3:HUL.InstRepos:41504669 Terms of Use This article was downloaded from Harvard University’s DASH repository, and is made available under the terms and conditions applicable to Open Access Policy Articles, as set forth at http:// nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of- use#OAP Draft version January 30, 2018 Typeset using LATEX twocolumn style in AASTeX62 AAS WorldWide Telescope: Seamless, Cross-Platform Data Visualization Engine for Astronomy Research, Education, and Democratizing Data Philip Rosenfield,1 Jonathan Fay,1 Ronald K Gilchrist,1 Chenzhou Cui,2 A. David Weigel,3 Thomas Robitaille,4 Oderah Justin Otor,1 and Alyssa Goodman5 1American Astronomical Society 1667 K St NW Suite 800 Washington, DC 20006, USA 2National Astronomical Observatories, Chinese Academy of Sciences 20A Datun Road, Chaoyang District Beijing, 100012, China 3Christenberry Planetarium, Samford University 800 Lakeshore Drive Birmingham, AL 35229, USA 4Aperio Software Ltd. Headingley Enterprise and Arts Centre, Bennett Road Leeds, LS6 3HN, United Kingdom 5Harvard Smithsonian Center for Astrophysics 60 Garden St.
    [Show full text]
  • Space Astronomy in the 90S
    Space Astronomy in the 90s Jonathan McDowell April 26, 1995 1 Why Space Astronomy? • SHARPER PICTURES (Spatial Resolution) The Earth’s atmosphere messes up the light coming in (stars twinkle, etc). • TECHNICOLOR (X-ray, infrared, etc) The atmosphere also absorbs light of different wavelengths (col- ors) outside the visible range. X-ray astronomy is impossible from the Earth’s surface. 2 What are the differences between satellite instruments? • Focussing optics or bare detectors • Wavelength or energy range - IR, UV, etc. Different technology used for different wavebands. • Spatial Resolution (how sharp a picture?) • Spatial Field of View (how large a piece of sky?) • Spectral Resolution (can it tell photons of different energies apart?) • Spectral Field of View (bandwidth) • Sensitivity • Pointing Accuracy • Lifetime • Orbit (hence operating efficiency, background, etc.) • Scan or Point What are the differences between satellites? • Spinning or 3-axis pointing (older satellites spun around a fixed axis, precession let them eventually see different parts of the sky) • Fixed or movable solar arrays (fixed arrays mean the spacecraft has to point near the plane perpendicular to the solar-satellite vector) 3 • Low or high orbit (low orbit has higher radiation, atmospheric drag, and more Earth occultation; high orbit has slower preces- sion and no refurbishment opportunity) • Propulsion to raise orbit? • Other consumables (proportional counter gas, attitude control gas, liquid helium coolant) 4 What are the differences in operation? • PI mission vs. GO mission PI = Principal Investigator. One of the people responsible for building the satellite. Nowadays often referred to as IPIs (In- strument PIs). GO = Guest Observer. Someone who just want to use the satel- lite.
    [Show full text]
  • Particle Acceleration in Solar Flares What Is the Link Between Heating and Particle Acceleration?
    Energetic Particles in the Solar Atmosphere (X- ray diagnostics) Nicole Vilmer LESIA, Observatoire de Paris, CNRS, UPMC, Université Paris-Diderot The Sun as a Particle Accelerator: First detection of energetic protons from the Sun(1942) (related to a solar flare) First X-ray observations of solar flares (1970) Chupp et al., 1974 First observations of -ray lines from solar flares (OSO7/Prognoz 1972) Since then many more observations With e.g. RHESSI (2002-2018) And also INTEGRAL, FERMI >120000 X-ray flares observed by RHESSI (NASA/SMEX; 2002-2018) But still a limited number of gamma- ray line flares ~30 Solar flare: Sudden release of magnetic energy Heating Particle acceleration X-rays 6-8 keV 25-80 keV 195 Å 304 Å 21 aug 2002 (extreme ultraviolet) 335 Å 15 fev 2011 HXR/GR diagnostics of energetic electrons and ions SXR emission Hot Plasma (7to 8 MK ) HXR emission Bremsstrahlung from non-thermal electrons Prompt -ray lines : Deexcitation lines(C and 0) (60%) Signature of energetic ions (>2 MeV/nuc) Neutron capture line: p –p ; p-α and p-ions interactions Production of neutrons Collisional slowing down of neutrons Radiative capture on ambient H deuterium + 2.2 MeV. line RHESSI Observations X/ spectrum Thermal components T= 2 10 7 K T= 4 10 7 K Electron bremsstrahlung Ultrarelativistic -ray lines Electron (ions > 3 MeV/nuc) Bremsstrahlung (INTEGRAL) SMM/GRS PHEBUS/GRANAT FERMI/LAT observations RHESSI Pion decay radiation(ions > ~300MeV/nuc) Particle acceleration in solar flares What is the link between heating and particle acceleration? Where are the acceleration sites? What is the transport of particles from acceleration sites to X/ γ ray emission sites? What are the characteristic acceleration times? RHESSI How many energetic particles? Energy spectra? Relative abundances of energetic ions? RHESSI Which acceleration mechanisms in solar flares? Shock acceleration? Stochastic acceleration? (wave-particle interaction) Direct Electric field acceleration.
    [Show full text]
  • Experiments on the Differential Vlbi Measurements with the Former Russian Deep Space Network
    EXPERIMENTS ON THE DIFFERENTIAL VLBI MEASUREMENTS WITH THE FORMER RUSSIAN DEEP SPACE NETWORK Igor E. Molotov(1,2,3) (1)Bear Lakes Radio Astronomy Station of Central (Pulkovo) Astronomical Observatory, Pulkovskoye chosse 65/1, Saint-Petersburg, 196140, Russia , E-mail: [email protected] (2)Keldysh Institute of Applied Mathematics, Miusskaja sq. 4, 125047 Moscow, Russia (3)Central Research Institute for Machine Building, 4 Pionerskaya Street, Korolev, 141070, Russia ABSTRACT The differential VLBI technique (delta-VLBI) is applied transforms the signals into video frequencies, which for measuring spacecraft position with accuracy up to 1 then are sampled with 1- or 2-bit quantization, formatted in any standard VLBI format (Mk-4, S2, K-4, mas. This procedure allows to link the sky position of object with the position of close ICRF quasar on the Mk-2) and recorded on magnetic tapes or PC-disks celestial sphere. Few delta-VLBI measurements can together with precise clock using VLBI terminal. All frequency transformations are connected with atomic urgently improve the knowledge of object trajectory in the times of critical maneuvers. frequency standard. The tapes/disks from all radio telescopes of VLBI array are collected at data The Russian Deep Space Network that was based on processing center, where the data are cross-correlated. three large antennas: 70 m in Evpatoria (Ukraine) and The processing is aimed to measure the time delay of Ussuriysk (Far East), and 64 m in Bear Lakes (near emitted wavefront arrival to receiving antennas, and Moscow) arranged the trial delta-VLBI experiments frequency of interference (fringe rate), that contain the with help of four scientific institutions.
    [Show full text]
  • GRANAT/WATCH Catalogue of Cosmic Gamma-Ray Bursts: December 1989 to September 1994? S.Y
    ASTRONOMY & ASTROPHYSICS APRIL I 1998,PAGE1 SUPPLEMENT SERIES Astron. Astrophys. Suppl. Ser. 129, 1-8 (1998) GRANAT/WATCH catalogue of cosmic gamma-ray bursts: December 1989 to September 1994? S.Y. Sazonov1,2, R.A. Sunyaev1,2, O.V. Terekhov1,N.Lund3, S. Brandt4, and A.J. Castro-Tirado5 1 Space Research Institute, Russian Academy of Sciences, Profsoyuznaya 84/32, 117810 Moscow, Russia 2 Max-Planck-Institut f¨ur Astrophysik, Karl-Schwarzschildstr 1, 85740 Garching, Germany 3 Danish Space Research Institute, Juliane Maries Vej 30, DK 2100 Copenhagen Ø, Denmark 4 Los Alamos National Laboratory, MS D436, Los Alamos, NM 87545, U.S.A. 5 Laboratorio de astrof´ısica Espacial y F´ısica Fundamental (LAEFF), INTA, P.O. Box 50727, 28080 Madrid, Spain Received May 23; accepted August 8, 1997 Abstract. We present the catalogue of gamma-ray bursts celestial positions (the radius of the localization region is (GRB) observed with the WATCH all-sky monitor on generally smaller than 1 deg at the 3σ confidence level) board the GRANAT satellite during the period December of short-lived hard X-ray sources, which include GRBs. 1989 to September 1994. The cosmic origin of 95 bursts Another feature of the instrument relevant to observa- comprising the catalogue is confirmed either by their lo- tions of GRBs is that its detectors are sensitive over an calization with WATCH or by their detection with other X-ray energy range that reaches down to ∼ 8 keV, the do- GRB experiments. For each burst its time history and main where the properties of GRBs are known less than information on its intensity in the two energy ranges at higher energies.
    [Show full text]
  • Spektr-RG All-Sky Survey Will Be a Major Step Forward for X-Ray Astronomy, Which Celebrated Its 50Th Anniversary a Few Years Ago
    CONTEXT The Spektr-RG all-sky survey will be a major step forward for X-ray astronomy, which celebrated its 50th anniversary a few years ago. 1962. Professor Riccardo Giacconi and his team are the first to identify X-ray emission originating from outside the Solar system (a neutron star dubbed Sco X-1). In 2002, he is awarded the Nobel Prize in Physics for this feat and the following discoveries of distant X-ray sources. 1970–1973. The first X-ray all-sky survey in the 2–20 keV energy band is carried out by the Uhuru space observatory (NASA). It discovers more than 300 X-ray sources in our Milky Way and beyond. 1977–1979. An even more sensitive survey is carried out by the HEAO-1 (NASA) space observatory at energies from 0.25 to 180 keV. 1989-1998. Over the initial four years of directed observations, the Granat astrophysical observatory (USSR) observes many galactic and extra-galactic X-ray sources with emphasis on the deep imaging of the Center of our Galaxy in the hard (40-150 keV) and soft (4-20 keV) X-ray ranges. Unique maps of the Galactic Center in X- and gamma- rays are created; black holes, neutron stars and the first microquasar are discovered. Then Granat carries out a sensitive all-sky survey in the 40 to 200 keV energy band. 1990–1999. In its first six months of operation the ROSAT space observatory (DLR, NASA) performs a deep all-sky survey in the soft X-ray band (0.1–2.4 keV).
    [Show full text]
  • Insight-HXMT) Satellite
    SCIENCE CHINA Physics, Mechanics & Astronomy • Article • January 2016 Vol.59 No.1: 000000 doi: 10.1007/s11433-000-0000-0 Overview to the Hard X-ray Modulation Telescope (Insight-HXMT) Satellite ShuangNan Zhang1,2*,TiPei Li1,2,3, FangJun Lu1, LiMing Song1, YuPeng Xu1, CongZhan Liu1, Yong Chen1, XueLei Cao1, QingCui Bu1, Ce Cai1,2, Zhi Chang1, Gang Chen1, Li Chen4, TianXiang Chen1, Wei Chen1, YiBao Chen3, YuPeng Chen1, Wei Cui1,3, WeiWei Cui1, JingKang Deng3, YongWei Dong1, YuanYuan Du1, MinXue Fu3, GuanHua Gao1,2, He Gao1,2, Min Gao1, MingYu Ge1, YuDong Gu1, Ju Guan1, Can Gungor1, ChengCheng Guo1,2, DaWei Han1, Wei Hu1, Yan Huang1,Yue Huang1,2, Jia Huo1, ShuMei Jia1, LuHua Jiang1, WeiChun Jiang1, Jing Jin1, YongJie Jin5, Lingda Kong1,2, Bing Li1, ChengKui Li1, Gang Li1, MaoShun Li1, Wei Li1, Xian Li1, XiaoBo Li1, XuFang Li1, YanGuo Li1, ZiJian Li1,2, ZhengWei Li1, XiaoHua Liang1, JinYuan Liao1, Baisheng Liu1, GuoQing Liu3, HongWei Liu1, ShaoZhen Liu1, XiaoJing Liu1, Yuan Liu6, YiNong Liu5, Bo Lu1, XueFeng Lu1, Qi Luo1,2, Tao Luo1, Xiang Ma1, Bin Meng1, Yi Nang1,2, JianYin Nie1, Ge Ou1, JinLu Qu1, Na Sai1,2, RenCheng Shang3,, GuoHong Shen7, XinYing Song1, Liang Sun1, Ying Tan1, Lian Tao1, WenHui Tao1, YouLi Tuo1,2, Chun- Qin Wang7, GuoFeng Wang1, HuanYu Wang1, Juan Wang1, WenShuai Wang1, YuSa Wang1, XiangYang Wen1, BoBing Wu1, Mei Wu1, GuangCheng Xiao1,2, Shuo Xiao1,2, ShaoLin Xiong1, He Xu1, LinLi Yan1,2, JiaWei Yang1, Sheng Yang1, YanJi Yang1, Qibin Yi1, JiaXi Yu1, Bin Yuan7, AiMei Zhang1, ChunLei Zhang1, ChengMo Zhang1, Fan Zhang1, HongMei
    [Show full text]
  • China's Shiyan Weixing Satellite Programme, 2014-2017
    SPACE CHRONICLE A BRITISH INTERPLANETARY SOCIETY PUBLICATION Vol. 71 No.1 2018 MONUMENTAL STATUES TO LOCAL LIVING COSMONAUTS CHINA’S SHIYAN WEIXING SPEKTR AND RUSSIAN SPACE SCIENCE SATELLITE PROGRAMME FIRST PICTURES OF EARTH FROM A SOVIET SPACECRAFT REPORTING THE RIGHT STUFF? Press in Moscow During the Space Race SINO-RUSSIAN ISSUE ISBN 978-0-9567382-2-6 JANUARY 20181 Submitting papers to From the editor SPACE CHRONICLE DURING THE WEEKEND of June 3rd and 4th 2017, the 37th annual Sino- Chinese Technical Forum was held at the Society’s Headquarters in London. Space Chronicle welcomes the submission Since 1980 this gathering has grown to be one of the most popular events in the for publication of technical articles of general BIS calendar and this year was no exception. The 2017 programme included no interest, historical contributions and reviews less than 17 papers covering a wide variety of topics, including the first Rex Hall in space science and technology, astronautics Memorial Lecture given by SpaceFlight Editor David Baker and the inaugural Oleg and related fields. Sokolov Memorial Paper presented by cosmonaut Anatoli Artsebarsky. GUIDELINES FOR AUTHORS Following each year’s Forum, a number of papers are selected for inclusion in a special edition of Space Chronicle. In this issue, four such papers are presented ■ As concise as the content allows – together with an associated paper that was not part the original agenda. typically 5,000 to 6,000 words. Shorter papers will also be considered. Longer The first paper, Spektr and Russian Space Science by Brian Harvey, describes the papers will only be considered in Spektr R Radio Astron radio observatory – Russia’s flagship space science project.
    [Show full text]
  • ART-P/Granat Observations of the X-Ray Pulsar 4U0115+634 During the Outburst in February 1990 A
    Astronomy Letters, Vol. 26, No. 1, 2000, pp. 1–8. Translated from Pis’ma v Astronomicheskiœ Zhurnal, Vol. 26, No. 1, 2000, pp. 3–12. Original Russian Text Copyright © 2000 by Lutovinov, Grebenev, Sunyaev. ART-P/Granat Observations of the X-ray Pulsar 4U0115+634 during the Outburst in February 1990 A. A. Lutovinov1, S. A. Grebenev1*, and R. A. Sunyaev1, 2 1 Space Research Institute, Russian Academy of Sciences, ul. Profsoyuznaya 84/32, Moscow, 117810 Russia 2 Max-Planck Institut für Astrophysik, Garching, Germany Received April 6, 1999 Abstract—Observations of the transient X-ray pulsar 4U0115+634 with the ART-P telescope aboard the Granat Observatory during the outburst in February 1990 are presented. The source exhibited a strong, regular and irregular variability, including X-ray bursts of duration 300–500 s. Two absorption features were detected in the source’s photon spectrum at ~12 and ~22 keV, which were interpreted as the lines of resonance scattering of its emission at the first and second cyclotron harmonics. The magnetic-field strength B on the neutron-star surface that corresponds to these lines is ~1.3 × 1012 G. The ratio of the line energies slightly differs from the harmonic ratio 1 : 2. Moreover, this ratio and the line energies themselves vary appreciably with phase on a time scale of one pulsation period. The dependence of other spectral parameters for 4U0115+634 on pulse phase is investigated. © 2000 MAIK “Nauka/Interperiodica”. INTRODUCTION erties, they differ markedly from “soft” transients, X-ray novae. In general, its spectrum is well described by a The transient X-ray source 4U0115+634 was dis- power law with a photon index α ~ 0.5 and with an covered by the Uhuru satellite during its outburst in exponential cutoff at energies above 10–15 keV.
    [Show full text]
  • Arxiv:1505.03651V1 [Astro-Ph.HE] 14 May 2015 2 R
    Astron Astrophys Rev manuscript No. (will be inserted by the editor) High-Mass X-ray Binaries in the Milky Way A closer look with INTEGRAL R. Walter A. A. Lutovinov E. · · Bozzo S. S. Tsygankov · Received: December 30, 2014 / Accepted: May 12, 2015 Abstract High-mass X-ray binaries are fundamental in the study of stellar evolution, nucleosynthesis, structure and evolution of galaxies and accretion processes. Hard X-rays observations by INTEGRAL and Swift have broad- ened significantly our understanding in particular for the super-giant systems in the Milky Way, which number has increased by almost a factor of three. INTEGRAL played a crucial role in the discovery, study and understanding of heavily obscured systems and of fast X-ray transients. Most super-giant systems can now be classified in three categories: classical/obscured, eccentric and fast transient. The classical systems feature low eccentricity and variability factor of 103, mostly driven by hydrodynamic phenomena occurring on scales larger∼ than the accretion radius. Among them, systems with short orbital periods and close to Roche-Lobe overflow or with slow winds, appear highly obscured. In eccentric systems, the variability amplitude can reach even higher factors, because of the contrast of the wind density along the orbit. Four super-giant systems, featuring fast outbursts, very short orbital periods and anomalously low accretion rates, are not yet understood. Simulations of the accretion processes on relatively large scales have pro- gressed and reproduce parts of the observations. The combined effects of wind Roland Walter & Enrico Bozzo ISDC, Geneva Observatory, University of Geneva, Ch. d’Ecogia 16, CH-1290 Versoix, Switzerland.
    [Show full text]
  • Early Danish Grb Experiments – and Some for the Future?
    Gamma-ray Bursts: 15 Years of GRB Afterglows A.J. Castro-Tirado, J. Gorosabel and I.H. Park (eds) EAS Publications Series, 61 (2013) 15–25 EARLY DANISH GRB EXPERIMENTS – AND SOME FOR THE FUTURE? N. Lund1 Abstract. By 1975 the hunt for GRB counterparts had been on for almost ten years without success. Gamma burst instruments of that day provided little or no directional data in themselves. Positions could be extracted only using the time delay technique – potentially accurate but very slow. Triggered by a japanese report of a balloon instrument for GRB studies based on a Rotation Modulation Collimator we at the Danish Space Research Institute started the development of an RMC detector for GRBs, the WATCH wide field monitor. Four WATCH units were flown on the Soviet Granat satellites, and one on ESA’s EURECA satellite. The design and results will be summarized. Now, 35 years later, recent detector developments may allow the construction of WATCH-type instruments able to fit weight, power and data-wise into 1 kg cubesats. This could provide the basis for a true all-sky monitor with 100 percent duty cycle for rare, bright events. 1 Introduction The Danish Space Research Institute (DSRI) was set up in 1968 to provide a national focal point for a national participation in the European Space Research Organisation, ESRO. Prior to the formation of DSRI the national efforts in space had been directed towards the ionosphere because of the importance of this at- mospheric region for radio communications with Greenland. The first director of DSRI was Bernard Peters, a well known figure in the post war cosmic ray re- search.
    [Show full text]
  • Astron: Venera Turned Space Telescope | Drew Ex Machina
    Posts Offsite Publications About Contact Astron: Venera Turned Space Telescope Home Astronomy Astronomical Instruments Astron: Venera Turned Space Telescope Enter your search January 7, 2016 Astronomical Instruments , Astronomy , Spaceflight , Unmanned Spaceflight 3 Comments 1980s, Astron, NPO Lavochkin, Scientific Satellites, Soviet Venus Missions, Space observatories ABOUT THE AUTHOR Welcome My website is dedicated to the presentation and discussion of my past and current professional work. My areas of interest include remote sensing, spaceflight, astronomy and astrobiology. Andrew LePage - Physicist Learn More When thinking about the old Soviet space program, people usually remember its long history of crewed space missions or its somewhat checkered lunar and planetary programs or constellations of military and intelligence satellites that outnumbered their western counterparts. Not as well known are the myriad science-related space missions performing many of the same studies as science missions in the West. Among these was a very capable yet little-known space telescope from the 1980s called Astron. CATEGORIES The Astron Spacecraft Astrobiology Astrobiology Missions The primary objective of the Soviet Astron mission was to perform astronomical observations of stars, active galaxies and other energetic phenomena Astronomical Instruments in the ultraviolet (UV) region of the spectrum. Since Earth’s atmosphere largely blocks UV, astronomical observations at these wavelengths must be conducted from space. Astron’s science program was the responsibility of a team at the Crimean Astrophysical Observatory led by Alexander Astronomy Boyarchuk. Like many other Soviet science missions of the time, there was international participation – in this case, with the French space agency, CNES. The Astron spacecraft itself was the responsibility of NPO Lavochkin which is best known as the builders of the Soviet’s lunar and planetary Drew's Basement probes since 1966.
    [Show full text]