The polarization of the cosmic microwave background is rich in information but obscured by foreground emission from the Milky Way’s interstellar medium (ISM). To uncover relationships between the underlying turbulent ISM and the foreground power spectra, we simulated a suite of driven, magnetized, turbulent models of the ISM, varying the fluid properties via the sonic Mach number, MS , and magnetic (Alfvén) Mach number, MA . We measure the power spectra of density (ρ), velocity (v), magnetic field (H), total projected intensity (T), parity-even polarization (E), and parity-odd polarization (B). We find that the slopes of all six quantities increase with MS . Most increase with MA , while the magnetic field spectrum steepens with MA . By comparing spectral slopes of E and B to those measured by Planck, we infer typical values of MS and MA for the ISM. As the fluid velocity increases, MS>4 , the ratio of BB power to EE power increases to approach a constant value near the Planck-observed value of ∼0.5, regardless of the magnetic field strength. We also examine correlation coefficients between projected quantities, and find that r ^TE ≈ 0.3, in agreement with Planck, for appropriate combinations of MS and MA . Finally, we consider parity-violating correlations r ^TB and r ^EB.

中文翻译：

---

普朗克尘埃偏振功率谱与强超音速湍流一致


宇宙微波背景的偏振信息丰富，但被银河系星际介质（ISM）的前景发射所掩盖。为了揭示底层湍流 ISM 和前景功率谱之间的关系，我们模拟了 ISM 的一套驱动、磁化、湍流模型，通过声速马赫数改变流体特性，中号S ，和磁（阿尔芬）马赫数，中号一个。我们测量密度的功率谱（ ρ ）， 速度 （ v ）、磁场（ H ），总预计强度（时间），奇偶偶极化（乙）和奇偶偏振（乙）。我们发现所有六个量的斜率随着中号S 。 大多数增加与中号一个，而磁场频谱随着中号一个。通过比较光谱斜率乙和乙根据普朗克测量的值，我们推断出典型值中号S和中号一个对于ISM。随着流体速度的增加，中号S > 4 ，无论磁场强度如何，BB 功率与 EE 功率之比都会增加到接近普朗克观测值 ∼0.5 的恒定值。我们还检查了预测量之间的相关系数，发现r ^TE ≈ 0。3、与普朗克一致，对于适当的组合中号S和 中号一个。最后，我们考虑违反奇偶校验的相关性r^结核病和r ^EB 。