银河系快速射电暴源SGR 1935+2154低频射电辐射的约束

中文摘要 AI 辅助

我们利用普希金诺射电天文台的大型相控阵（LPA）在约110 MHz频率上对银河系磁星SGR 1935+2154（一个著名的快速射电暴（FRB）源）进行了射电脉冲搜索。针对2020年两个活跃期（3月至5月和9月至11月，每日覆盖约3.5分钟）的数据，我们采用了专门针对类FRB单脉冲和类脉冲星周期信号的新方法进行分析。未发现显著的类FRB脉冲。通过蒙特卡洛模拟，我们推导出爆发率的3σ上限：对于对数正态能量分布，当平均单色各向同性光度$L_{\nu{\rm,mean}}\sim1.3\times{10}^{29}~{\rm{erg~s^{-1}~ {Hz}^{-1}}}$且自然对数空间弥散$\sigma\sim0.85$时，上限约为${10}^{1.5}~{\rm{d}}^{-1}$；而对于幂律分布，当指数$\beta\lesssim3.0$且最小平均单色各向同性光度$L_{\nu{\rm{,min}}}\lesssim0.7\times{10}^{25}~{\rm{erg~s^{-1}~{Hz}^{-1}}}$时，上限约为${10}^{1.8}~{\rm{d}}^{-1}$。当按SGR 1935+2154已知的3.24781628秒周期折叠时，注意到一个微弱脉冲（信噪比<3.16），但其显著性不足以可靠探测类脉冲星发射信号。任何可能的周期发射的平均单色各向同性光度的保守上限为$2.08\times{10}^{19}~{\rm{erg~s^{-1}~{Hz}^{-1}}}$。我们的结果为SGR 1935+2154的爆发率提供了有意义的低频上限，并暗示在米波段存在非常微弱的类脉冲星辐射。

英文摘要

We present a search for radio pulses from the Galactic magnetar SGR 1935+2154, a well-known source of fast radio bursts (FRBs), at $\sim$110 MHz using the Large Phased Array (LPA) of the Pushchino Radio Astronomy Observatory. Data from two active periods in 2020 (March -- May and September -- November, with $\sim 3.5$ minutes of daily coverage) were analyzed with new methods tailored to both FRB-like single pulses and pulsar-like periodic signals. No significant FRB-like pulses were found. Using Monte Carlo simulations, $3σ$ upper limits were derived for the burst rate: for a log-normal energy distribution the limit is $\sim$${10}^{1.5}~{\rm{d}}^{-1}$ for a mean of average monochromatic isotropic luminosity $L_{ν{\rm ,mean}}\sim1.3\times{10}^{29}~{\rm{erg~s^{-1}~ {Hz}^{-1}}}$ and a natural log-space scatter of $σ\sim0.85$; while for a power-law distribution it is $\sim$${10}^{1.8}~{\rm{d}}^{-1}$ for an index $β\lesssim3.0$ and a minimum average monochromatic isotropic luminosity $L_{ν{\rm{,min}}}\lesssim0.7\times{10}^{25}~{\rm{erg~s^{-1}~{Hz}^{-1}}}$. When folded at the known 3.24781628 s period of SGR 1935+2154, a weak pulse was noted (S/N $<$ 3.16), but the significance is insufficient for a secure detection of the pulsar-like emission signal. A conservative upper limit on the average monochromatic isotropic luminosity of any possible periodic emission is $2.08\times{10}^{19}~{\rm{erg~s^{-1}~{Hz}^{-1}}}$. Our results offer meaningful low-frequency upper limits on the burst rate of SGR 1935+2154, and hint for very faint pulsar-like radiation at meter wavelengths.

发表机构

• Nanjing University（南京大学）
• National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）
• University of Chinese Academy of Sciences（中国科学院大学）
• Lebedev Physical Institute of Astro Space Center of Pushchino Radio Astronomy Observatory（普希奇诺射电天文观测站太空物理中心列别捷夫物理研究所）
• State Key Laboratory of Radio Astronomy and Technology, NAOC, Chinese Academy of Sciences（中国科学院国家天文台射电天文与技术重点实验室）
• Institute for Frontiers in Astronomy and Astrophysics, Beijing Normal University（北京师范大学前沿天文与天体物理研究院）
• Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education（教育部现代天文与天体物理重点实验室（南京大学））
• Institute of Mathematical Problems of Biology, Branch of Keldysh Institute of Applied Mathematics of Russian Academy of Sciences（俄罗斯科学院凯尔迪什应用数学研究所生物数学问题研究所）

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27 pages, 13 figures