Galactic Supernova Remnant Candidates Discovered by THOR
Galactic Supernova Remnant Candidates Discovered by THOR
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DOI：
10.1051/0004-6361/201731019
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发表时间：
2017-05
影响因子：
6.5
通讯作者：
L. Anderson;L. Anderson;Yuting Wang;S. Bihr;M. Rugel;H. Beuther;F. Bigiel;E. Churchwell;S. Glover;A. Goodman;T. Henning;M. Heyer;R. Klessen;H. Linz;S. Longmore;K. Menten;J. Ott;N. Roy;J. Soler;J. Stil;J. Urquhart;J. Urquhart
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文献类型：
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作者：
L. Anderson;L. Anderson;Yuting Wang;S. Bihr;M. Rugel;H. Beuther;F. Bigiel;E. Churchwell;S. Glover;A. Goodman;T. Henning;M. Heyer;R. Klessen;H. Linz;S. Longmore;K. Menten;J. Ott;N. Roy;J. Soler;J. Stil;J. Urquhart;J. Urquhart
上下文与预期相比，银河系中已知的超新星遗迹（SNRs）数量有相当大的不足。这种缺陷被认为是由于缺乏敏感的无线电连续数据造成的。对扩展的低表面亮度射电源的探测可能会发现新的银河SNR，但是与更大的H II区域人口的混淆使得识别这些特征具有挑战性。然而，SNR可以从H II区域分离，使用它们的显着较低的中红外（MIR）无线电连续强度比。目标。我们的目标是通过定位缺乏MIR对应物的扩展无线电连续源来找到银河系盘中缺失的SNR候选者。方法.我们使用的高分辨率1-2 GHz的连续数据相结合的HI，OH，银河系（THOR）和低分辨率VLA 1.4 GHz的银河系平面调查（VGPS）连续数据，连同MIR数据从斯皮策GLIMPSE，斯皮策MIPSGAL，和WISE调查，以确定SNR候选人。为了确保候选者不会与H II区混淆，我们从银河系H II区的WISE目录中排除了无线电连续源，该目录包含银河系中所有已知和候选的H II区。结果我们在67.4度> l > 17.5 β的THOR和VGPS联合调查区域定位了76个新的银河SNR候选者，|B| <= 1.25度，并测量52个先前已知SNR的无线电通量密度。候选SNR具有与已知SNR相似的空间分布，尽管我们注意到在盾牌螺旋臂的切线点l附近有大量新的候选SNR。与已知区域相比，候选SNR的角度平均较小，6.4' +/- 4.7'对11.0' +/-7.8'，并且具有较低的积分通量密度。结论. THOR调查表明，敏感的无线电连续数据可以发现大量的SNR候选者，并且这些候选者可以使用无线电和MIR数据的组合来有效地识别。如果这76个候选者被确认为真实的信噪比，例如使用无线电极化测量或通过推导无线电频谱指数，这将使调查区域内已知的银河信噪比数量增加一倍以上。然而，这种大的增加仍然会在已知的和预期的SNR总体之间留下大约两倍的差异。
Context. There is a considerable deficiency in the number of known supernova remnants (SNRs) in the Galaxy compared to that expected. This deficiency is thought to be caused by a lack of sensitive radio continuum data. Searches for extended low-surface brightness radio sources may find new Galactic SNRs, but confusion with the much larger population of H II regions makes identifying such features challenging. SNRs can, however, be separated from H II regions using their significantly lower mid-infrared (MIR) to radio continuum intensity ratios. Aims. Our goal is to find missing SNR candidates in the Galactic disk by locating extended radio continuum sources that lack MIR counterparts. Methods. We use the combination of high-resolution 1-2 GHz continuum data from The HI, OH, Recombination line survey of the Milky Way (THOR) and lower-resolution VLA 1.4 GHz Galactic Plane Survey (VGPS) continuum data, together with MIR data from the Spitzer GLIMPSE, Spitzer MIPSGAL, and WISE surveys to identify SNR candidates. To ensure that the candidates are not being confused with H II regions, we exclude radio continuum sources from the WISE Catalog of Galactic H II Regions, which contains all known and candidate H II regions in the Galaxy. Results. We locate 76 new Galactic SNR candidates in the THOR and VGPS combined survey area of 67.4 degrees > l > 17.5 beta, |b| <= 1.25 degrees and measure the radio flux density for 52 previously-known SNRs. The candidate SNRs have a similar spatial distribution to the known SNRs, although we note a large number of new candidates near l similar or equal to 30 degrees, the tangent point of the Scutum spiral arm. The candidates are on average smaller in angle compared to the known regions, 6.4' +/- 4.7' versus 11.0' +/- 7.8', and have lower integrated flux densities. Conclusions. The THOR survey shows that sensitive radio continuum data can discover a large number of SNR candidates, and that these candidates can be efficiently identified using the combination of radio and MIR data. If the 76 candidates are confirmed as true SNRs, for example using radio polarization measurements or by deriving radio spectral indices, this would more than double the number of known Galactic SNRs in the survey area. This large increase would still, however, leave a discrepancy between the known and expected SNR populations of about a factor of two.