The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. VI. Radio Constraints on a Relativistic Jet and Predictions for Late-time Emission from the Kilonova Ejecta
The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. VI. Radio Constraints on a Relativistic Jet and Predictions for Late-time Emission from the Kilonova Ejecta
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DOI：
10.3847/2041-8213/aa905d
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发表时间：
2017-10
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通讯作者：
K. Alexander;E. Berger;W. Fong;P. G. Williams;C. Guidorzi;R. Margutti;B. Metzger;J. Annis;P. Blanchard;D. Brout;Duncan A. Brown;H. Chen;R. Chornock;P. Cowperthwaite;M. Drout;T. Eftekhari;J. Frieman;J. Frieman;D. Holz;M. Nicholl;A. Rest;A. Rest;M. Sako;M. Soares-Santos;V. Villar
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作者：
K. Alexander;E. Berger;W. Fong;P. G. Williams;C. Guidorzi;R. Margutti;B. Metzger;J. Annis;P. Blanchard;D. Brout;Duncan A. Brown;H. Chen;R. Chornock;P. Cowperthwaite;M. Drout;T. Eftekhari;J. Frieman;J. Frieman;D. Holz;M. Nicholl;A. Rest;A. Rest;M. Sako;M. Soares-Santos;V. Villar
我们介绍了甚大阵列(VLA)和阿塔卡马大毫米/亚毫米阵列(ALMA)对GW170817的射电观测，GW170817是双中子星合并产生的第一个激光干涉仪引力波天文台(LIGO)/室女座引力波(GW)事件，也是第一个与电磁(EM)对应物发生的GW事件。我们的数据包括在厘米(合并后13.7小时)和毫米(合并后2.41天)波段发现光学瞬变后的第一次观测。我们在合并后19.47天和39.23天检测到6 GHz的微弱发射，但在更早的2.46天的观测中没有检测到。在合并后0.6至30天的时间内，我们没有在10-97.5千兆赫的光学对应物位置检测到厘米/毫米的发射，这排除了能量≳10 48erg的轴上短伽马射线暴(SGRb)。对于基准SGRB参数，我们的限制要求观察者视角为≳20°。射电和X射线数据可以共同解释为喷流能量为∼10 49-10 50 erg的SGRB在n∼10−4-10−2 cm−3的均匀密度环境中爆炸的余辉发射，从距喷流轴20°-40°的∼角度观察。利用我们的光曲线和频谱模拟的结果，结合外星密度的推断，我们预测在5-10年的时间尺度上，由于千诺瓦(KN)抛射的减速而产生的晚间射电辐射的出现，将通过下一代无线电设施保持数十年的可探测状态，使∼170817成为一个引人注目的长期射电监测目标。
We present Very Large Array (VLA) and Atacama Large Millimeter/submillimeter Array (ALMA) radio observations of GW170817, the first Laser Interferometer Gravitational-wave Observatory (LIGO)/Virgo gravitational wave (GW) event from a binary neutron star merger and the first GW event with an electromagnetic (EM) counterpart. Our data include the first observations following the discovery of the optical transient at both the centimeter (13.7 hr post-merger) and millimeter (2.41 days post-merger) bands. We detect faint emission at 6 GHz at 19.47 and 39.23 days after the merger, but not in an earlier observation at 2.46 days. We do not detect cm/mm emission at the position of the optical counterpart at frequencies of 10–97.5 GHz at times ranging from 0.6 to 30 days post-merger, ruling out an on-axis short gamma-ray burst (SGRB) for energies ≳ 10 48 erg. For fiducial SGRB parameters, our limits require an observer viewer angle of ≳20°. The radio and X-ray data can be jointly explained as the afterglow emission from an SGRB with a jet energy of ∼ 10 49 – 10 50 erg that exploded in a uniform density environment with n ∼ 10 − 4 – 10 − 2 cm−3, viewed at an angle of ∼20°–40° from the jet axis. Using the results of our light curve and spectral modeling, in conjunction with the inference of the circumbinary density, we predict the emergence of late-time radio emission from the deceleration of the kilonova (KN) ejecta on a timescale of ∼5–10 years that will remain detectable for decades with next-generation radio facilities, making GW170817 a compelling target for long-term radio monitoring.