The Astrophysical Journal · 1994 · 1.3K citations · 0 references
Natural SciencesAstronomyPhysicsAstrophysicsCosmologyGamma-ray AstronomyGamma-ray BurstsGravitational CollapseCompact Stellar RemnantsExternal ShocksInternal ShocksRelativistic OutflowsShock-associated WavesStellar Core CollapseUnsteady Shock Waves
Gamma‑ray burst triggers last only a few seconds, far longer than the ~10⁻³‑second dynamical timescale of a compact stellar‑mass object, and collapse or merger events are expected to produce unsteady mass or energy fluxes on timescales from 10⁻³ to 10 seconds. The model assumes energy is released as a high‑Γ outflow whose ~2‑fold fluctuations produce relativistic internal motions that generate internal shocks. With Γ≈10², dissipation occurs beyond the photosphere, converting a large fraction of outflow energy into non‑thermal radiation, offering a cosmological burst mechanism that requires less extreme Γ values and baryonic contamination than earlier models. Published in The Astrophysical Journal, August 1994, DOI 10.1086/187446, arXiv:astro‑ph/9404038.
view Abstract Citations (1148) References (14) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Unsteady Outflow Models for Cosmological Gamma-Ray Bursts Rees, M. J. ; Meszaros, P. Abstract The 'event' that triggers a gamma ray burst cannot last for more than a few seconds. This is, however, long compared with the dynamical timescale of a compact stellar-mass object ($\sim 10^{-3}$ seconds). Energy is assumed to be released as an outflow with high mean lorentz factor $\Gamma$. But a compact stellar-mass collapse or merger is, realistically, likely to generate a mass (or energy) flux that is unsteady on some timescales in the range $10^{-3}$ - 10 seconds. If $\Gamma$ fluctuates by a factor of $\sim 2$ around its mean value, relative motions within the outflowing material will themselves (in the comoving frame) be relativistic, and can give rise to internal shocks. For $\Gamma \sim 10^2$, the resultant dissipation occurs outside the 'photosphere' and can convert a substantial fraction of the overall outflow energy into non-thermal radiation. This suggests a mechanism for cosmological bursts that demands less extreme assumptions (in respect of $\Gamma$-values, freedom from baryonic contamination, etc) than earlier proposals. Publication: The Astrophysical Journal Pub Date: August 1994 DOI: 10.1086/187446 arXiv: arXiv:astro-ph/9404038 Bibcode: 1994ApJ...430L..93R Keywords: Compacting; Gamma Ray Bursts; Mathematical Models; Stellar Mass; Baryons; Collapse; Lorentz Contraction; Relativistic Velocity; Shock Waves; Space Radiation; COSMOLOGY: MISCELLANEOUS; GAMMA RAYS: BURSTS; GAMMA RAYS: THEORY; Astrophysics E-Print: 7 pages, plain TeX full text sources arXiv | ADS |