论文标题
检测具有镜头快速无线电爆发的宇宙弦
Detecting Cosmic Strings with Lensed Fast Radio Bursts
论文作者
论文摘要
最近从脉冲星定时观测结果报道的相关红噪声可能是由宇宙弦发射的随机重力波的指示，这些引力波在大统一能量尺度附近的原始相过渡过程中形成。不幸的是，宇宙弦的已知探针，即宇宙微波背景各向异性和弦脉外星系的弦镜头，对于$Gμ= 10^{ - 10} -10} -10} -10} -10^{ - 7} $的低弦张力不足以解释此推定信号。我们表明，宇宙字符串对快速无线电爆发（FRB）的强力重力镜头是探测该弦张力值范围的潜在明确的途径。图像对的弦镜头对具有相同的放大倍数和奇偶校验，并且具有$ \ sim 10^2 \，\，（g \，μ/10^{ - 8}）的典型时间延迟^2 $秒。每个FRB的独特光谱指纹，以及在无线电波的电场时间序列中检测相关性的可能性，可以验证字符串镜头解释。非常长的基线干涉法（VLBI）观察可以在空间上解析图像对，并根据图像分离在字符串张力上提供下限。对于FRB红移分布的几种不同模型，我们计算FRB镜头率是FRB检测号的函数。我们发现，根据即将到来的调查和弦的检测率的估计，检测$ \ sim 10^5 $ frb的调查可以发现强大的镜头事件，用于$gμ\ simeq 10^{ - 7} $的字符串张力。较大的FRB调查，例如平方公里阵列（SKA）的2阶段，有可能显着提高弦乐张力的灵敏度至$gμ\ simeq 10^{ - 9} $。
Correlated red noise recently reported from pulsar timing observations may be an indication of stochastic gravitational waves emitted by cosmic strings that formed during a primordial phase transition near the Grand Unification energy scale. Unfortunately, known probes of cosmic strings, namely the Cosmic Microwave Background anisotropies and string lensing of extragalactic galaxies, are not sensitive enough for low string tensions of $Gμ= 10^{-10}-10^{-7}$ that are needed to explain this putative signal. We show that strong gravitational lensing of Fast Radio Bursts (FRBs) by cosmic strings is a potentially unambiguous avenue to probe that range of string tension values. The image pair of string lensing are expected to have identical magnification factor and parity, and have a typical time delay of $\sim 10^2\,\,(G\,μ/10^{-8})^2$ seconds. The unique spectral fingerprint of each FRB, as well as the possibility to detect correlations in the time series of the electric field of the radio waves, will enable verification of the string lensing interpretation. Very-Long-Baseline Interferometry (VLBI) observations can spatially resolve the image pair and provide a lower bound on the string tension based on the image separation. We calculate the FRB lensing rate as a function of FRB detection number for several different models of the FRB redshift distribution. We find that a survey detecting $\sim 10^5$ FRBs, in line with estimates for the detection rate of the forthcoming survey CHORD, can uncover a strong lensing event for a string tension of $Gμ\simeq 10^{-7}$. Larger FRB surveys, such as Phase 2 of the Square Kilometre Array (SKA), have the potential to significantly improve the sensitivity on the string tension to $Gμ\simeq 10^{-9}$.
