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  1. AU="Workman, Jared C"
  2. AU=Kirkham Alexander P S
  3. AU="Martínez-Cortés, Ismael"
  4. AU="Suresh, K."
  5. AU=Kishi Takuya
  6. AU="Moreira, Helena"
  7. AU="Malta, C-E"
  8. AU="Karaji, Niloofar"
  9. AU="Tjempakasari, Artaria"
  10. AU=Sepulveda-Crespo Daniel

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  1. Artikel ; Online: Late Time Afterglow Observations Reveal a Collimated Relativistic Jet in the Ejecta of the Binary Neutron Star Merger GW170817.

    Lazzati, Davide / Perna, Rosalba / Morsony, Brian J / Lopez-Camara, Diego / Cantiello, Matteo / Ciolfi, Riccardo / Giacomazzo, Bruno / Workman, Jared C

    Physical review letters

    2018  Band 120, Heft 24, Seite(n) 241103

    Abstract: The binary neutron star (BNS) merger GW170817 was the first astrophysical source detected in gravitational waves and multiwavelength electromagnetic radiation. The almost simultaneous observation of a pulse of gamma rays proved that BNS mergers are ... ...

    Abstract The binary neutron star (BNS) merger GW170817 was the first astrophysical source detected in gravitational waves and multiwavelength electromagnetic radiation. The almost simultaneous observation of a pulse of gamma rays proved that BNS mergers are associated with at least some short gamma-ray bursts (GRBs). However, the gamma-ray pulse was faint, casting doubt on the association of BNS mergers with the luminous, highly relativistic outflows of canonical short GRBs. Here we show that structured jets with a relativistic, energetic core surrounded by slower and less energetic wings produce afterglow emission that brightens characteristically with time, as recently seen in the afterglow of GW170817. Initially, we only see the relatively slow material moving towards us. As time passes, larger and larger sections of the outflow become visible, increasing the luminosity of the afterglow. The late appearance and increasing brightness of the multiwavelength afterglow of GW170817 allow us to constrain the geometry of its ejecta and thus reveal the presence of an off-axis jet pointing about 30° away from Earth. Our results confirm a single origin for BNS mergers and short GRBs: GW170817 produced a structured outflow with a highly relativistic core and a canonical short GRB. We did not see the bright burst because it was beamed away from Earth. However, approximately one in 20 mergers detected in gravitational waves will be accompanied by a bright, canonical short GRB.
    Sprache Englisch
    Erscheinungsdatum 2018-06-15
    Erscheinungsland United States
    Dokumenttyp Journal Article
    ZDB-ID 208853-8
    ISSN 1079-7114 ; 0031-9007
    ISSN (online) 1079-7114
    ISSN 0031-9007
    DOI 10.1103/PhysRevLett.120.241103
    Datenquelle MEDical Literature Analysis and Retrieval System OnLINE

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  2. Buch ; Online: Particle-in-cell simulations of particle energization from low Mach number fast mode shocks

    Park, Jaehong / Workman, Jared C. / Blackman, Eric G. / Ren, Chuang / Siller, Robert

    2012  

    Abstract: Astrophysical shocks are often studied in the high Mach number limit but weakly compressive fast shocks can occur in magnetic reconnection outflows and are considered to be a site of particle energization in solar flares. Here we study the microphysics ... ...

    Abstract Astrophysical shocks are often studied in the high Mach number limit but weakly compressive fast shocks can occur in magnetic reconnection outflows and are considered to be a site of particle energization in solar flares. Here we study the microphysics of such perpendicular, low Mach number collisionless shocks using two-dimensional particle-in-cell (PIC) simulations with a reduced ion/electron mass ratio and employ a moving wall boundary method for initial generation of the shock. This moving wall method allows for more control of the shock speed, smaller simulation box sizes, and longer simulation times than the commonly used fixed wall, reflection method of shock formation. Our results, which are independent of the shock formation method, reveal the prevalence shock drift acceleration (SDA) of both electron and ions in a purely perpendicular shock with Alfv\'en Mach number $M_A=6.8$ and ratio of thermal to magnetic pressure $\beta=8$. We determine the respective minimum energies required for electrons and ions to incur SDA. We derive a theoretical electron distribution via SDA that compares to the simulation results. We also show that a modified two-stream instability due to the incoming and reflecting ions in the shock transition region acts as the mechanism to generate collisionless plasma turbulence that sustains the shock.
    Schlagwörter Astrophysics - Solar and Stellar Astrophysics ; Physics - Plasma Physics ; Physics - Space Physics
    Thema/Rubrik (Code) 621
    Erscheinungsdatum 2012-02-29
    Erscheinungsland us
    Dokumenttyp Buch ; Online
    Datenquelle BASE - Bielefeld Academic Search Engine (Lebenswissenschaftliche Auswahl)

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