论文标题
在磁化流出中逐渐耗散的GRB光谱
GRB Spectrum from Gradual Dissipation in a Magnetized Outflow
论文作者
论文摘要
伽马射线爆发（GRB）及时发射光谱的建模有时还需要（Quasi-）热光谱分量除了频带函数。在光电发射模型中，预计通过光层耗散扩大的突出的热成分将以光泽半径释放，$ r _ {\ rm pH} \ sim10^{12} {12} \，$ cm。我们考虑了一种超相关的强烈磁性流出流出，并在$ r <r_s $下进行逐渐且连续的磁性耗散的条纹磁场结构，可加热和加速流动，从而导致lorentz因子$γ（r）=γ_=γ_=γ_\ infty \ infty \ min [1，r/r/r/r/r/r _ r_s） $ r _ {\ rm pH} <r_s $。在没有条纹/野外逆转的高度变化的磁化流出中，也有望在高度变化的磁化流出中进行类似的动力学和能量耗散率。考虑了两种粒子能量注入模式：（a）幂律电子，例如通过磁重新连接加速，（b）所有电子（和$ e^\ pm $ - $ pairs）的连续分布加热，例如由于MHD不稳定性。使用时间分辨的能光谱使用数值代码获得，该数值代码将光子电子旋律等离子体的动力学方程进化。 We find that (i) the thermal component peaks at $(1+z)E_{\rm pk}\sim0.2-1\,$MeV, for a source at redshift $z$, and becomes subdominant if the total injected energy density exceeds the thermal one, (ii) power-law electrons cool mainly by synchrotron emission whereas mildly relativistic and almost monoenergetic electrons in通过在热峰光子上构成的分布式加热方案（iii），两种情况都可以在$ e _ {\ e {\ rm br} \大约e _ {\ rm th} $中产生低能量的突破，（iv）$ 0.5（iv）$ 0.5（iv）undim undist in Indim undies in Indist in In Is Poter in In Is Poter in In Is POWER IS POWER IS POWER IS POWER IS POWER nt POWE分布式加热方案。能量依赖性的线性极化可以区分两个能量注射案例。
Modeling of gamma-ray burst (GRB) prompt emission spectra sometimes requires a (quasi-) thermal spectral component in addition to the Band function. In photospheric emission models, a prominent thermal component broadened by sub-photospheric dissipation is expected to be released at the photospheric radius, $r_{\rm ph}\sim10^{12}\,$cm. We consider an ultra-relativistic strongly magnetized outflow with a striped-wind magnetic-field structure undergoing gradual and continuous magnetic energy dissipation at $r<r_s$ that heats and accelerates the flow, leading to a bulk Lorentz factor $Γ(r)=Γ_\infty\min[1,(r/r_s)^{1/3}]$, where typically $r_{\rm ph}<r_s$. Similar dynamics and energy dissipation rates are also expected in highly-variable magnetized outflows without stripes/field-reversals. Two modes of particle energy injection are considered: (a) power-law electrons, e.g. accelerated by magnetic reconnection, and (b) continuous distributed heating of all electrons (and $e^\pm$-pairs), e.g. due to MHD instabilities. Time-resolved energy spectra are obtained using a numerical code that evolves coupled kinetic equations for a photon-electron-positron plasma. We find that (i) the thermal component peaks at $(1+z)E_{\rm pk}\sim0.2-1\,$MeV, for a source at redshift $z$, and becomes subdominant if the total injected energy density exceeds the thermal one, (ii) power-law electrons cool mainly by synchrotron emission whereas mildly relativistic and almost monoenergetic electrons in the distributed heating scenario cool by Comptonization on thermal peak photons, (iii) both scenarios can yield a low-energy break at $E_{\rm br}\approx E_{\rm th}$, and (iv) the $0.5(1+z)^{-1}\,$keV X-ray emission is suppressed in the power-law injection case, but it is expected for the distributed heating scenario. Energy-dependent linear polarization can differentiate between the two energy injection cases.
