Finding evidence for inflation and the origin of galactic magnetic fields with CMB surveys
Finding evidence for inflation and the origin of galactic magnetic fields with CMB surveys
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DOI：
10.1103/physrevd.105.063537
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发表时间：
2022-01
影响因子：
5
通讯作者：
Sayan Mandal;N. Sehgal;T. Namikawa
中科院分区：
文献类型：
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作者：
Sayan Mandal;N. Sehgal;T. Namikawa
在星系中观测到的 µG 磁场的起源尚不清楚。一种有希望的情况是，膨胀过程中产生的磁场（在 Mpc 尺度上大于 0.1 nG）在结构形成过程中被绝热压缩到星系中的 µ G 强度。因此，检测到 0 以上的尺度不变原初磁场 (PMF)。重组后 Mpc 尺度上的 1 nG 表明星系磁场的暴胀起源。这也将提供令人信服的证据，证明暴胀的发生，因为只有暴胀机制才能在 Mpc 尺度上产生如此强大的、尺度不变的磁场。相反，将尺度不变 PMF 强度限制在 0 以下。 1 nG 意味着暴胀情景不是主要起源，因为如此弱的 PMF 无法通过绝热压缩放大到足以产生我们今天观察到的银河场的强度。我们发现，未来 CMB 调查对各向异性双折射的测量将能够将 Mpc 尺度膨胀 PMF 的灵敏度提高一个数量级，特别是 CMB-HD 会将上限降低到 0 。 072 nG 在 95% C.L. 处，低于临界值 0 。 1 nG 阈值用于排除纯粹的通货膨胀起源。如果存在通货膨胀 PMF，我们发现 CMB-HD 调查将能够以约 3 σ 或更高的显着性检测它们，从而为通货膨胀本身提供证据。
The origin of the µ G magnetic fields observed in galaxies is unknown. One promising scenario is that magnetic fields generated during inflation, larger than 0.1 nG on Mpc scales, were adiabatically compressed to µ G strengths in galaxies during structure formation. Thus, detecting a scale-invariant primordial magnetic field (PMF) above 0 . 1 nG on Mpc scales just after recombination would indicate an inflationary origin of galactic magnetic fields. This would also provide compelling evidence that inflation occurred since only an inflationary mechanism could generate such a strong, scale-invariant magnetic field on Mpc scales. In contrast, constraining the scale-invariant PMF strength to be below 0 . 1 nG would imply an inflationary scenario is not the primary origin, since such weak PMFs cannot be amplified enough via adiabatic compression to produce the strength of the galactic fields we observe today. We find that measurements of anisotropic birefringence by future CMB surveys will be able to improve the sensitivity to Mpc-scale inflationary PMFs by an order of magnitude, and, in particular, that CMB-HD would lower the upper bound to 0 . 072 nG at the 95% C.L., which is below the critical 0 . 1 nG threshold for ruling out a purely inflationary origin. If inflationary PMFs exist, we find that a CMB-HD survey would be able to detect them with about 3 σ significance or higher, providing evidence for inflation itself.