Particle energy cascade in the intergalactic medium
Particle energy cascade in the intergalactic medium
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DOI：
10.1111/j.1365-2966.2010.16387.x
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发表时间：
2009-11
期刊：
影响因子：
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通讯作者：
Carmelo Evoli;M. Valdes;A. Ferrara
中科院分区：
文献类型：
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作者：
Carmelo Evoli;M. Valdes;A. Ferrara
我们研究了将能量为Ein的初级电子注入星系际介质（IGM）所产生的高能（Ein≤1 TeV）级联的发展。为此，我们开发了新的代码medea（蒙特卡洛能量沉积分析），其中包括弱应力和逆康普顿（IC）过程，以及H/He碰撞电离和激发，以及电子-电子碰撞。级联能量划分为加热、激发和电离，不仅主要取决于IGM电离分数xe，还取决于宇宙微波背景（CMB）光子上IC引起的红移z。虽然轫致辐射在大多数条件下并不重要，但在能量Ein≥1mev时，集成电路成为主要优势。在注入能量Ein≤100 MeV时，集成电路的主要作用是显著提高了转化为低能光子（hν 104 eV）的能量比例，并可以自由地流向观察者。给出了分数能量沉积与红移、Ein和电离分数的完整关系表。我们的结果可以用于许多天体物理学背景，与高z宇宙中衰变/湮灭暗物质（DM）候选者的研究相关的明显应用。
We study the development of high-energy (Ein≤ 1 TeV) cascades produced by a primary electron of energy Ein injected into the intergalactic medium (IGM). To this aim we have developed the new code medea (Monte Carlo Energy Deposition Analysis) which includes Bremsstrahlung and inverse Compton (IC) processes, along with H/He collisional ionizations and excitations, and electron–electron collisions. The cascade energy partition into heating, excitations and ionizations depends primarily not only on the IGM ionized fraction, xe, but also on redshift, z, due to IC on cosmic microwave background (CMB) photons. While Bremsstrahlung is unimportant under most conditions, IC becomes largely dominant at energies Ein≥ 1 MeV. The main effect of IC at injection energies Ein≤ 100 MeV is a significant boost of the fraction of energy converted into low-energy photons (hν 104 eV) and can free stream to the observer. Complete tables of the fractional energy depositions as a function of redshift, Ein and ionized fraction are given. Our results can be used in many astrophysical contexts, with an obvious application related to the study of decaying/annihilating dark matter (DM) candidates in the high-z Universe.