论文标题
用矮星系模拟限制原始磁场
Constraining the primordial magnetic field with dwarf galaxy simulations
论文作者
论文摘要
使用一组宇宙学水力学模拟，我们通过研究它们对矮星系的形成和演变的影响来限制原始磁场的特性。我们通过它们在小长度尺度（$ k \ geq 10 \，h \，h \，h \，\ rm {mpc^{ - 1}} $）中进行了大量的模拟（仅8个暗物质和72个化学流动力学），包括原始磁场（$ k \ geq 10 \，h \ geq 10 \，h \ geq 10 \，$ k \ geq \ geq 10 \，$ k \ geq { - 1}} $）。我们探索了各种各样的原始磁场，其强度为$b_λ$从$ 0.05 $到$ 0.50 \，\ textrm {ng} $和磁能谱斜率$ n_b $从$ -2.9 $到$ -2.1 $。强磁场以高振幅为特征（$b_λ= 0.50，\，0.20 \，\ textrm {ng} $，带有$ n_b = -2.9 $）或陡峭的初始功率频谱坡度（$ n_b = -2.1，-2.1，-2.1，-2.4 $，带有$b_λ= 0.05 \，\ 0.05 \，\，\ textrm} $ $ 10^7 $至$ 10^9 \，\ rm {m} _ {\ odot} $。在这种情况下，新兴的星系会看到他们的恒星形成率强烈提高。它们比没有原始磁场的对应物变得更发光和金属。这种强大的田地是由于无法再现矮星系的缩放关系而排除的。他们预测，矮星系是宇宙不切实际的早期回报的起源，并且在当地群体中生产了发光的卫星。在相应质量下影响原始密度场的较弱磁场$ \ sillsim 10^6 \，\ rm {m} _ {\ odot} $，产生大量的迷你深色晕孔，绕矮人绕矮人，但是目前的透镜观察范围不足。这项研究首次允许基于矮星系的现实宇宙学模拟来限制原始磁场的性质。
Using a set of cosmological hydro-dynamical simulations, we constrained the properties of primordial magnetic fields by studying their impact on the formation and evolution of dwarf galaxies. We performed a large set of simulations (8 dark matter only and 72 chemo-hydrodynamical) including primordial magnetic fields through the extra density fluctuations they induce at small length scales ($k \geq 10\,h\,\rm{Mpc^{-1}}$) in the matter power spectrum. We explored a large variety of primordial magnetic fields with strength $B_λ$ ranging from $0.05$ to $0.50\,\textrm{nG}$ and magnetic energy spectrum slopes $n_B$ from $-2.9$ to $-2.1$. Strong magnetic fields characterized by a high amplitude ($B_λ=0.50,\,0.20\,\textrm{nG}$ with $n_B=-2.9$) or by a steep initial power spectrum slope ($n_B=-2.1,-2.4$, with $B_λ=0.05\,\textrm{nG}$) induce perturbations in the mass scales from $10^7$ to $10^9\,\rm{M}_{\odot}$. In this context emerging galaxies see their star formation rate strongly boosted. They become more luminous and metal rich than their counterparts without primordial magnetic fields. Such strong fields are ruled out by their inability to reproduce the observed scaling relations of dwarf galaxies. They predict dwarf galaxies to be at the origin of an unrealistically early reionization of the Universe and also overproduce luminous satellites in the Local Group. Weaker magnetic fields impacting the primordial density field at corresponding masses $\lesssim 10^6\,\rm{M}_{\odot}$, produce a large number of mini dark halos orbiting the dwarfs, however out of reach for current lensing observations. This study allows for the first time to constrain the properties of primordial magnetic fields based on realistic cosmological simulations of dwarf galaxies.
