Seven Years of Coordinated Chandra–NuSTAR Observations of SN 2014C Unfold the Extreme Mass-loss History of Its Stellar Progenitor
Seven Years of Coordinated Chandra–NuSTAR Observations of SN 2014C Unfold the Extreme Mass-loss History of Its Stellar Progenitor
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DOI：
10.3847/1538-4357/ac8b14
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发表时间：
2022-06
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通讯作者：
D. Brethauer;R. Margutti;D. Milisavljevic;M. Bietenholz;R. Chornock;D. Coppejans;F. Colle;A. Hajela-A.
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作者：
D. Brethauer;R. Margutti;D. Milisavljevic;M. Bietenholz;R. Chornock;D. Coppejans;F. Colle;A. Hajela-A.
本文介绍了我们利用Chandra和努斯塔对SN 2014 C进行的长达7年的宽带X射线观测活动的结果。这些协调的观测代表了在核心坍缩后的几年中，在0.3-80 keV能量范围内的年轻河外SN的演变的第一次观察。我们发现，SN 2014 C从普通的Ib型SN到具有大量氢发射的相互作用SN的光谱变态伴随着发光X射线，在爆炸后1000天达到L x 5.6 × 1040 erg s−1（0.3-100 keV），之后随着L x t −1而下降。宽带X射线谱是热起源的，并显示出峰后冷却的明显证据，T（t）= 20 keV（t/tpk）−0.5。亚keV能量的软X射线会受到来自局部SN环境的大量光电吸收，NHint（t）为<$3 ×1022（t/400天）−1.4cm−2。我们将这些发现解释为SN激波与致密（n = 105 − 106 cm−3）、富含氢的盘状星周介质（CSM）相互作用的结果，CSM的内径为102 × 1016 cm，延伸至1017 cm。根据NHint（t）的下降和X射线光度的演化，我们推断CSM的质量为1.2 f-2.0 f）M <$，其中f是体积填充因子。我们将SN 2014 C的背景下，121核心塌陷SNe的证据与厚拱星介质的强烈冲击相互作用。最后，我们强调了当前的质量损失理论（包括波驱动的质量损失，二进制的相互作用，和线驱动风）所面临的挑战时，解释广泛的动态范围的CSM参数从观测推断。
We present the results from our 7 yr long broadband X-ray observing campaign of SN 2014C with Chandra and NuSTAR. These coordinated observations represent the first look at the evolution of a young extragalactic SN in the 0.3–80 keV energy range in the years after core collapse. We find that the spectroscopic metamorphosis of SN 2014C from an ordinary type Ib SN into an interacting SN with copious hydrogen emission is accompanied by luminous X-rays reaching L x ≈ 5.6 × 1040 erg s−1 (0.3–100 keV) at ∼1000 days post-explosion and declining as L x ∝ t −1 afterwards. The broadband X-ray spectrum is of thermal origin and shows clear evidence for cooling after peak, with T(t)≈20keV(t/tpk)−0.5 . Soft X-rays of sub-keV energy suffer from large photoelectric absorption originating from the local SN environment with NHint(t)≈3×1022(t/400days)−1.4cm−2 . We interpret these findings as the result of the interaction of the SN shock with a dense (n ≈ 105 − 106 cm−3), H-rich disk-like circumstellar medium (CSM) with inner radius ∼2 × 1016 cm and extending to ∼1017 cm. Based on the declining NHint(t) and X-ray luminosity evolution, we infer a CSM mass of ∼(1.2 f–2.0 f)M⊙ , where f is the volume filling factor. We place SN 2014C in the context of 121 core-collapse SNe with evidence for strong shock interaction with a thick circumstellar medium. Finally, we highlight the challenges that the current mass-loss theories (including wave-driven mass loss, binary interaction, and line-driven winds) face when interpreting the wide dynamic ranges of CSM parameters inferred from observations.