NGC 7469的射电监测：SN 2000英尺的晚期射电演化和NGC 7469的环核星暴
Radio monitoring of NGC 7469: Late time radio evolution of SN 2000ft and the circumnuclear starburst in NGC 7469
摘要：
利用8.4 GHz甚大阵（VLA）0.3“分辨率观测数据，对亮红外星系（LIRG）NGC 7469的射电辐射进行了长达8年的观测。我们的监测表明，无线电超新星SN 2000英尺的后期演化遵循与其光学薄相早期非常相似的下降。因此，SN 2000英尺的晚期射电辐射仍然是由其与超新星前恒星风的相互作用提供动力，而不是与星际介质（ISM）。实际上，在超新星年龄约为2127天时，超新星前风的冲压压力为ρ_w v_w^2 \approx 7.6 E-9 dyn/cm ^2，这明显大于SN 2000 ft附近ISM的预期压力。在这个年龄，SN冲击波的距离r_{sh \approx 0.06 pc，我们的观测正在探测SN与超新星爆发前5820年的致密物质的相互作用。从我们的VLA监测，我们估计，由超新星冲击扫起的质量约6年后的膨胀是\approx 0.29 M太阳，假设超新星的平均膨胀速度为10000公里/秒。我们还在VLA图像中搜索了最近爆发的核心塌陷超新星。除了SN 2000 ft（S_v \approx 1760 microJy）的峰值，相当于1.1E28 erg/s/Hz外，我们没有发现任何其他射电超新星（RSN）比\approx 6.0E26 erg/s/Hz更亮的证据，这表明自2000年以来没有其他I In型SN在NGC 7469的环核星暴中爆炸。
英文摘要：
We present the results of an eight-year long monitoring of the radio emission from the Luminous Infrared Galaxy (LIRG) NGC 7469, using 8.4 GHz Very Large Array (VLA) observations at 0.3'' resolution. Our monitoring shows that the late time evolution of the radio supernova SN 2000ft follows a decline very similar to that displayed at earlier times of its optically thin phase. The late time radio emission of SN 2000ft is therefore still being powered by its interaction with the presupernova stellar wind, and not with the interstellar medium (ISM). Indeed, the ram pressure of the presupernova wind is ρ_w v_w^2 \approx 7.6E-9 dyn/cm^2, at a supernova age of approximately 2127 days, which is significantly larger than the expected pressure of the ISM around SN 2000ft. At this age, the SN shock has reached a distance r_{sh \approx 0.06 pc, and our observations are probing the interaction of the SN with dense material that was ejected by the presupernova star about 5820 years prior to its explosion. From our VLA monitoring, we estimate that the swept-up mass by the supernova shock after about six years of expansion is \approx 0.29 M_sun, assuming an average expansion speed of the supernova of 10000 km/s. We also searched for recently exploded core-collapse supernovae in our VLA images. Apart from SN 2000ft (S_ν\approx 1760 microJy at its peak, corresponding to 1.1E28 erg/s/Hz, we found no evidence for any other radio supernova (RSN) more luminous than \approx 6.0E26 erg/s/Hz, which suggests that no other Type IIn SN has exploded since 2000 in the circumnuclear starburst of NGC 7469.
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