Discovery of a radio transient in M81
Discovery of a radio transient in M81
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DOI：
10.1093/mnras/stz1303
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发表时间：
2019-05
影响因子：
4.8
通讯作者：
G. Anderson;J. Miller-Jones;M. Middleton;R. Soria;R. Soria;D. Swartz;R. Urquhart;N. Hurley-Walker-N.-Hurley
中科院分区：
文献类型：
--
作者：
G. Anderson;J. Miller-Jones;M. Middleton;R. Soria;R. Soria;D. Swartz;R. Urquhart;N. Hurley-Walker-N.-Hurley
我们报道了在螺旋星系M81中发现的一个射电瞬变现象。2015年初，作为对M81进行的为期两年的调查的一部分，利用卡尔·G·詹斯基甚大阵列对M81进行了为期两年的调查，该调查由12个纪元组成。虽然在2014年9月12日没有被探测到，但它在2015年1月2日首次被探测到，从那时起，它在大约恒定的光度LR下保持可见，ν=1.5x0.1x1024erg S−1 Hz−1，观测频率为6 GHz，持续至少2个月。假设这是一个上升时间在2.6到112d之间的同步加速器事件，峰值光度(等分时)对应于最小能量1044≲Emin≲1046erg和喷流功率pmin∼1039erg S−1，这比大多数已知的X射线双星都要高。考虑到它的寿命，缺乏短期射电可变性，也没有任何多波长的对应物(X射线光度LX≲1036erg S−1)，它的行为与已知的银河系或河外X射线双星不同。M81的瞬变射电性质更接近于在M82中发现的不明射电瞬变43.78+59.3，它被认为是一个与类似SS 433的吸积源有关的射电星云。一种可能性是，新的M81瞬变和M82瞬变都可能是一个与离散吸积事件有关的短暂射电气泡的诞生，类似于从ULX Holmberg II X-1观测到的事件。然而，不能排除其他鉴定，包括来自微弱超新星或背景活动星系的长期超新星冲击波与周围介质的相互作用。
We report the discovery of a radio transient in the spiral galaxy M81. The transient was detected in early 2015 as part of a two-year survey of M81 made up of 12 epochs using the Karl G. Jansky Very Large Array. While undetected on 2014 September 12, the source was first detected on 2015 January 2, from which point it remained visible at an approximately constant luminosity of LR, ν = 1.5 ± 0.1 × 1024 erg s−1 Hz−1 at the observing frequency of 6 GHz for at least 2 months. Assuming this is a synchrotron event with a rise-time between 2.6 and 112 d, the peak luminosity (at equipartition) corresponds to a minimum energy of 1044 ≲ Emin ≲ 1046 erg and jet power of Pmin ∼ 1039 erg s−1, which are higher than most known X-ray binaries. Given its longevity, lack of short-term radio variability, and the absence of any multiwavelength counterpart (X-ray luminosity Lx ≲ 1036 erg s−1), it does not behave like known Galactic or extragalactic X-ray binaries. The M81 transient radio properties more closely resemble the unidentified radio transient 43.78+59.3 discovered in M82, which has been suggested to be a radio nebula associated with an accreting source similar to SS 433. One possibility is that both the new M81 transient and the M82 transient may be the birth of a short-lived radio bubble associated with a discrete accretion event similar to those observed from the ULX Holmberg II X-1. However, it is not possible to rule out other identifications including long-term supernova shockwave interactions with the surrounding medium from a faint supernova or a background active galaxy.