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Full-sky survey searching for ultra-narrow-band artificial cw signals: analysis of the results of Project META

机译：用于超窄带人工CW信号的全天性调查：分析项目元的结果

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Project META (Megachannel ExtraTerrestrial Assay), a full-sky survey for artificial narrow-band signals, has been conducted from the Harvard/Smithsonian 26 m radiotelescope at Agassiz Station and from one of the two 30 m radiotelescopes of the Instituto Argentino de Radioastronomia (IAR). The search was performed near the 1420 MHz line of neutral hydrogen, and its second harmonic, using two 8.4 $MUL 10$+6$/ channel Fourier spectrometers of 0.05 Hz resolution and 400 kHz of instantaneous bandwidth. The observing frequency was corrected both for motions with respect to three astronomical inertial frames, and for the effect of Earth's rotation, which provides a characteristic changing signature for narrow-band signals of extraterrestrial origin. Among the 6 $MUL 10$+13$/ spectral channels searched in the northern hemisphere, Horowitz and Sagan reported 37 candidates events exceeding the average threshold of 1.7 $MUL 10$+$MIN@23$/ W m$+$MIN@2$/, while in the southern hemisphere among 2 $MUL 10$+13$/ spectral channels analyzed we found 19 events exceeding the same threshold. The strongest signals that survive culling for terrestrial interference lie in or near the Galactic Plane. The first high resolution southern target search around 71 stars ($MIN@90 degrees $LSEQ $delta $LSEQ $MIN@10 degrees), was performed, using the facilities of IAR. For this search, we have selected, 'all' the stars at distances nearer than 5 pc and those stars that are falling between $PLU@0.6 and $PLU@1.0 in the (B-V) color index, with spectral class V, that are at distances nearer that 15.5 pc. Stars bluer that $PLU@0.6 have main sequence lifetimes that are too short to provide long-term environmental stability, while stars redder than $PLU@1.0 cannot presently be detected. The observations were done with the same spectrometer, tracking each star, at least for 60 minutes, at three different epochs. The third part of the program consisted in observing simultaneously identical celestial coordinates ($MIN@30 degrees $LSEQ $delta $LSEQ $MIN@10 degrees) between the Harvard/Smithsonian and the IAR's radio telescopes. Finally, we use the Cordes-Lazio-Sagan Model based in scattering theory, simulations and empirical constraints on interstellar scintillations to discuss the intermittency of radio signals from extraterrestrial intelligence. It is showed that these narrow-band non-repeating 'events' found by Project META can be generated by (a) radiometer noise fluctuations, (b) a population of constant galactic sources which undergo deep fading and amplification due to interstellar scintillation, consistent with ETI transmissions and (c) real, transient signals of either terrestrial or extraterrestrial origin. The Bayesian test shows that hypothesis (b) and (c) are both highly preferred to (a), but the first two are about equally likely. Using this analysis we discuss the best observing strategies to determine the real origin of these 'events'.
机译：项目META（MEGACHANNEL外星动物分析）是一款用于人工窄带信号的全天候调查，已从Agassiz Station的哈佛/史密森尼26米射频射频进行，并从ISTITUTO ARGENTINO de RadioStroneIvia（ IAR）。搜索在1420 MHz系列中性氢气线附近进行，其二次谐波，使用0.05 Hz分辨率的两个8.4 $ MUL 10 $ + 6 $ /沟道傅里叶频率光谱仪和400 kHz的瞬时带宽。针对三个天文惯性帧的运动校正了观察频率，以及地球旋转的效果，这提供了用于外星源的窄带信号的特征改变符号。在北半球搜索的6美元10美元+ 13美元/光谱渠道中，霍洛维茨和萨坎报告了37名候选人事件超过了1.7 $ MUL 10 $ + $最小@ 23 $ / W M $ + $最小@ 2 $ /，虽然在南半球的2美元中，但在2美元的价格中，10美元+ 13美元/频道频道分析我们发现19个事件超过相同的阈值。生存为陆地干扰的最强信号位于银河平面内或附近。第一个高分辨率南方目标搜索左右71颗星（$ min @ 90度$ lseq $ delta $ lseq $ min @ 10度），使用IAR的设施进行。对于此搜索，我们已选择“所有”距离更近于5个PC的距离和在（BV）颜色索引中落下的那些落下的星星，其中v距离较近的距离较近15.5个电脑。 STARS BLUER表示，USPLU@0.6具有太短的主要序列，无法提供长期的环境稳定性，而星星比SPLU@1.0不能默认。使用相同的光谱仪进行观察结果，跟踪每种星，至少在三种不同的时期至少60分钟。该计划的第三部分包括在哈佛/史密森尼和IAR的无线电望远镜之间同时观察同时相同的天体坐标（Min @ 30度$ LSEQ $ LESTA $ LSEQ $ MIN @ 10度）。最后，我们使用的Cordes - 拉齐奥 - 萨根基于散射理论，模拟和星际闪烁经验的约束模型由外星智能讨论的无线电信号的间歇。结果表明，由项目元发现的这些窄带非重复“事件”可以通过（a）辐射计噪声波动，（b）由于星际闪烁而经历深度衰落和扩增的恒定银源群，一致使用ETI传输和（c）陆地或外星起源的真实信号，瞬态信号。贝叶斯测试表明，假设（B）和（C）非常优选（a），但前两者均为同样可能。使用此分析，我们讨论了最佳观察策略，以确定这些“事件”的实际起源。

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