Jet propagations, breakouts, and photospheric emissions in collapsing massive progenitors of long-duration gamma-ray bursts

Hiroki Nagakura, Hirotaka Ito, Kenta Kiuchi, Shoichi Yamada

    Research output: Contribution to journalArticle

    71 Citations (Scopus)

    Abstract

    We investigate the following by two-dimensional axisymmetric relativistic hydrodynamical simulations: (1) jet propagations through an envelope of a rapidly rotating and collapsing massive star, which is supposed to be a progenitor of long-duration gamma-ray bursts (GRBs); (2) breakouts and subsequent expansions into stellar winds; and (3) the accompanying photospheric emissions. We find that if the envelope rotates uniformly almost at the mass shedding limit, its outer part eventually stops contracting when the centrifugal force becomes large enough. Then another shock wave is formed, propagates outward, and breaks out of the envelope into the stellar wind. Whether the jet or the centrifugal bounce-induced shock breaks out earlier depends on the timing of jet injection. If the shock breakout occurs earlier, owing to a later injection, the jet propagation and subsequent photospheric emissions are affected substantially. We pay particular attention to observational consequences of the difference in the timing of jet injection. We calculate optical depths to find the location of photospheres, extracting densities, and temperatures at appropriate retarded times from the hydrodynamical data. We show that the luminosity and observed temperature of the photospheric emissions are both much lower than those reported in previous studies. Although luminosities are still high enough for GRBs, the observed temperatures are lower than the energy at the spectral peak expected by the Yonetoku relation. This may imply that energy exchanges between photons and matter are terminated deeper inside or that some non-thermal processes are operating to boost photon energies.

    Original languageEnglish
    Article number80
    JournalAstrophysical Journal
    Volume731
    Issue number2
    DOIs
    Publication statusPublished - 2011 Apr 20

    Fingerprint

    gamma ray bursts
    propagation
    envelopes
    stellar winds
    injection
    shock
    luminosity
    time measurement
    energy
    centrifugal force
    photons
    photosphere
    acceleration (physics)
    shock wave
    massive stars
    optical thickness
    optical depth
    shock waves
    temperature
    energy transfer

    Keywords

    • black hole physics
    • hydrodynamics
    • radiation mechanisms: general
    • supernovae: general

    ASJC Scopus subject areas

    • Space and Planetary Science
    • Astronomy and Astrophysics

    Cite this

    Jet propagations, breakouts, and photospheric emissions in collapsing massive progenitors of long-duration gamma-ray bursts. / Nagakura, Hiroki; Ito, Hirotaka; Kiuchi, Kenta; Yamada, Shoichi.

    In: Astrophysical Journal, Vol. 731, No. 2, 80, 20.04.2011.

    Research output: Contribution to journalArticle

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