A Matched Survey for the Enigmatic Low Radio Frequency Transient ILT J225347+862146
A Matched Survey for the Enigmatic Low Radio Frequency Transient ILT J225347+862146
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DOI：
10.3847/1538-4357/ac4048
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发表时间：
2021-12
期刊：
影响因子：
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通讯作者：
Yuping 宇平 Huang 黃;M. Anderson;G. Hallinan;T. Joseph W. Lazio;D. Price;Y. Sharma
中科院分区：
文献类型：
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作者：
Yuping 宇平 Huang 黃;M. Anderson;G. Hallinan;T. Joseph W. Lazio;D. Price;Y. Sharma
在2011年由LOFAR发现的15jy低频无线电瞬变ILT J225347+862146预示着一个潜在的<100 MHz的无线电瞬变群体。然而，在类似的参数空间中，随后的瞬态搜索没有产生任何检测。我们检验了这样一个假设，即这些具有可比灵敏度的调查由于调查参数不匹配而错过了人口。特别是，LOFAR调查在60兆赫时仅使用195千赫的带宽，而其他调查则使用更高的频率或更宽的带宽。利用欧文斯谷射电天文台长波阵的137小时全天图像，我们进行了一个窄带瞬变搜索，时间尺度从10分钟到1天，带宽为722 kHz， 60 MHz，灵敏度为~ 10 Jy。为了模拟剩余的调查选择效应，我们引入了一种灵活的贝叶斯方法来推断瞬态速率。我们没有检测到任何瞬态，并发现令人信服的证据表明我们的未检测与ILT J225347+862146的检测不一致。在假定瞬态现象是天体物理现象的前提下，我们提出了两个可能解释我们未被探测到的假设。首先，与ILT J225347+862146相关的瞬变星群可能具有较低的全天密度和较强的时间聚类。其次，ILT J225347+862146可能是通量分布的一个极端例子，我们将其在15 Jy处的表面密度估计修正为1.1 × 10−7 deg−2,95%可信区间为（3.5 × 10−12,3.4 × 10−7）deg−2。最后，我们发现与ILT J225347+862146一致的先前确定的物体是420 pc的M矮星。
Discovered in 2011 with LOFAR, the 15 Jy low-frequency radio transient ILT J225347+862146 heralds a potentially prolific population of radio transients at <100 MHz. However, subsequent transient searches in similar parameter space yielded no detections. We test the hypothesis that these surveys at comparable sensitivity have missed the population due to mismatched survey parameters. In particular, the LOFAR survey used only 195 kHz of bandwidth at 60 MHz, while other surveys were at higher frequencies or had wider bandwidth. Using 137 hr of all-sky images from the Owens Valley Radio Observatory Long Wavelength Array, we conduct a narrowband transient search at ∼10 Jy sensitivity with timescales from 10 minutes to 1 day and a bandwidth of 722 kHz at 60 MHz. To model the remaining survey selection effects, we introduce a flexible Bayesian approach for inferring transient rates. We do not detect any transient and find compelling evidence that our nondetection is inconsistent with the detection of ILT J225347+862146. Under the assumption that the transient is astrophysical, we propose two hypotheses that may explain our nondetection. First, the transient population associated with ILT J225347+862146 may have a low all-sky density and display strong temporal clustering. Second, ILT J225347+862146 may be an extreme instance of the fluence distribution, of which we revise the surface density estimate at 15 Jy to 1.1 × 10−7 deg−2 with a 95% credible interval of (3.5 × 10−12, 3.4 × 10−7) deg−2. Finally, we find a previously identified object coincident with ILT J225347+862146 to be an M dwarf at 420 pc.