Cyclotron Lines in Highly Magnetized Neutron Stars R
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Determination of the Night Sky Background Around the Crab Pulsar Using Its Optical Pulsation
28th International Cosmic Ray Conference 2449 Determination of the Night Sky Background around the Crab Pulsar Using its Optical Pulsation E. O˜na-Wilhelmi1,2, J. Cortina3, O.C. de Jager1, V. Fonseca2 for the MAGIC collaboration (1) Unit for Space Physics, Potchefstroom University for CHE, Potchefstroom 2520, South Africa (2) Dept. de f´isica At´omica, Nuclear y Molecular, UCM, Ciudad Universitaria s/n, Madrid, Spain (3) Institut de Fisica de l’Altes Energies, UAB, Barcelona, Spain Abstract The poor angular resolution of imaging γ-ray telescopes is offset by the large collection area of the next generation telescopes such as MAGIC (17 m diameter) which makes the study of optical emission associated with some γ-ray sources feasible. In particular the optical photon flux causes an increase in the photomultiplier DC currents. Furthermore, the extremely fast response of PMs make them ideal detectors for fast (subsecond) optical transients and periodic sources like pulsars. The HEGRA CT1 telescope (1.8 m radius) is the smallest Cerenkovˆ telescope which has seen the Crab optical pulsations. 1. Method Imaging Atmospheric Cerenkovˆ Detectors (IACT) can be used to detect the optical emission of an astronomical object through the increase it generates in the currents of the camera pixels [7,3]. Since the Crab pulsar shows pulsed emission in the optical wavelengths with the same frequency as in radio and most probably of VHE γ-rays, we use the central pixel of CT1 [5] and MAGIC [1] to monitor the optical Crab pulsation. Before the Crab observations were performed, the expected rate of the Crab pulsar and background were estimated theoretically. -
The Star Newsletter
THE HOT STAR NEWSLETTER ? An electronic publication dedicated to A, B, O, Of, LBV and Wolf-Rayet stars and related phenomena in galaxies ? No. 70 2002 July-August http://www.astro.ugto.mx/∼eenens/hot/ editor: Philippe Eenens http://www.star.ucl.ac.uk/∼hsn/index.html [email protected] ftp://saturn.sron.nl/pub/karelh/uploads/wrbib/ Contents of this newsletter Call for Data . 1 Abstracts of 12 accepted papers . 2 Abstracts of 2 submitted papers . 10 Abstracts of 6 proceedings papers . 11 Jobs .......................................................................13 Meetings ...................................................................14 Call for Data The multiplicity of 9 Sgr G. Rauw and H. Sana Institut d’Astrophysique, Universit´ede Li`ege,All´eedu 6 Aoˆut, BˆatB5c, B-4000 Li`ege(Sart Tilman), Belgium e-mail: [email protected], [email protected] The non-thermal radio emission observed for a number of O and WR stars implies the presence of a small population of relativistic electrons in the winds of these objects. Electrons could be accelerated to relativistic velocities either in the shock region of a colliding wind binary (Eichler & Usov 1993, ApJ 402, 271) or in the shocks due to intrinsic wind instabilities of a single star (Chen & White 1994, Ap&SS 221, 259). Dougherty & Williams (2000, MNRAS 319, 1005) pointed out that 7 out of 9 WR stars with non-thermal radio emission are in fact binary systems. This result clearly supports the colliding wind scenario. In the present issue of the Hot Star Newsletter, we announce the results of a multi-wavelength campaign on the O4 V star 9 Sgr (= HD 164794; see the abstract by Rauw et al.). -
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A&A 601, A29 (2017) Astronomy DOI: 10.1051/0004-6361/201629685 & c ESO 2017 Astrophysics Delay-time distribution of core-collapse supernovae with late events resulting from binary interaction E. Zapartas1, S. E. de Mink1, R. G. Izzard2, S.-C. Yoon3, C. Badenes4, Y. Götberg1, A. de Koter1; 5, C. J. Neijssel1, M. Renzo1, A. Schootemeijer6, and T. S. Shrotriya6 1 Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands e-mail: [E.Zapartas;S.E.deMink]@uva.nl 2 Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK 3 Astronomy Program, Department of Physics and Astronomy, Seoul National University, 151–747 Seoul, Korea 4 Department of Physics and Astronomy & Pittsburgh Particle Physics, Astrophysics, and Cosmology Center (PITT-PACC), University of Pittsburgh, Pittsburgh, PA 15260, USA 5 Institute of Astronomy, KU Leuven, Celestijnenlaan 200 D, 3001 Leuven, Belgium 6 Argelander-Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany Received 11 September 2016 / Accepted 1 January 2017 ABSTRACT Most massive stars, the progenitors of core-collapse supernovae, are in close binary systems and may interact with their companion through mass transfer or merging. We undertake a population synthesis study to compute the delay-time distribution of core-collapse supernovae, that is, the supernova rate versus time following a starburst, taking into account binary interactions. We test the systematic robustness of our results by running various simulations to account for the uncertainties in our standard assumptions. We find that +9 a significant fraction, 15−8%, of core-collapse supernovae are “late”, that is, they occur 50–200 Myr after birth, when all massive single stars have already exploded. -
Rotating Wolf-Rayet Stars in a Post RSG/LBV Phase an Evolutionary Channel Towards Long-Duration Grbs?
A&A 547, A83 (2012) Astronomy DOI: 10.1051/0004-6361/201118664 & c ESO 2012 Astrophysics Rotating Wolf-Rayet stars in a post RSG/LBV phase An evolutionary channel towards long-duration GRBs? G. Gräfener1,J.S.Vink1, T. J. Harries2, and N. Langer3 1 Armagh Observatory, College Hill, Armagh BT61 9DG, UK 2 School of Physics and Astronomy, University of Exeter, Stocker Rd, Exeter EX4 4QL, UK 3 Argelander-Institut für Astronomie der Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany Received 16 December 2011 / Accepted 3 October 2012 ABSTRACT Context. Wolf-Rayet (WR) stars with fast rotating cores are thought to be the direct progenitors of long-duration gamma-ray bursts (LGRBs). A well accepted evolutionary channel towards LGRBs is chemically-homogeneous evolution at low metallicities, which completely avoids a red supergiant (RSG), or luminous blue variable (LBV) phase. On the other hand, strong absorption features with velocities of several hundred km s−1 have been found in some LGRB afterglow spectra (GRB 020813 and GRB 021004), which have been attributed to dense circumstellar (CS) material that has been ejected in a previous RSG or LBV phase, and is interacting with a fast WR-type stellar wind. Aims. Here we investigate the properties of Galactic WR stars and their environment to identify similar evolutionary channels that may lead to the formation of LGRBs. Methods. We compile available information on the spectropolarimetric properties of 29 WR stars, the presence of CS ejecta for 172 WR stars, and the CS velocities in the environment of 34 WR stars in the Galaxy. -
PSR J1740-3052: a Pulsar with a Massive Companion
Haverford College Haverford Scholarship Faculty Publications Physics 2001 PSR J1740-3052: a Pulsar with a Massive Companion I. H. Stairs R. N. Manchester A. G. Lyne V. M. Kaspi Fronefield Crawford Haverford College, [email protected] Follow this and additional works at: https://scholarship.haverford.edu/physics_facpubs Repository Citation "PSR J1740-3052: a Pulsar with a Massive Companion" I. H. Stairs, R. N. Manchester, A. G. Lyne, V. M. Kaspi, F. Camilo, J. F. Bell, N. D'Amico, M. Kramer, F. Crawford, D. J. Morris, A. Possenti, N. P. F. McKay, S. L. Lumsden, L. E. Tacconi-Garman, R. D. Cannon, N. C. Hambly, & P. R. Wood, Monthly Notices of the Royal Astronomical Society, 325, 979 (2001). This Journal Article is brought to you for free and open access by the Physics at Haverford Scholarship. It has been accepted for inclusion in Faculty Publications by an authorized administrator of Haverford Scholarship. For more information, please contact [email protected]. Mon. Not. R. Astron. Soc. 325, 979–988 (2001) PSR J174023052: a pulsar with a massive companion I. H. Stairs,1,2P R. N. Manchester,3 A. G. Lyne,1 V. M. Kaspi,4† F. Camilo,5 J. F. Bell,3 N. D’Amico,6,7 M. Kramer,1 F. Crawford,8‡ D. J. Morris,1 A. Possenti,6 N. P. F. McKay,1 S. L. Lumsden,9 L. E. Tacconi-Garman,10 R. D. Cannon,11 N. C. Hambly12 and P. R. Wood13 1University of Manchester, Jodrell Bank Observatory, Macclesfield, Cheshire SK11 9DL 2National Radio Astronomy Observatory, PO Box 2, Green Bank, WV 24944, USA 3Australia Telescope National Facility, CSIRO, PO Box 76, Epping, NSW 1710, Australia 4Physics Department, McGill University, 3600 University Street, Montreal, Quebec, H3A 2T8, Canada 5Columbia Astrophysics Laboratory, Columbia University, 550 W. -