论文标题
与H.E.S.S的碰撞风二进制η车的检测非常高能量的γ射线发射
Detection of very-high-energy γ-ray emission from the colliding wind binary η Car with H.E.S.S
论文作者
论文摘要
目标。长期以来,人们一直怀疑碰撞的风二元系统是高能(HE; 100 MeV <E <100 GEV)γ射线发射器。 ηCar是该对象类别中最突出的成员,并被确认会发射γ射线从数百个MEV到〜100 GEV能量。这项工作旨在搜索和表征从2014年最后一次的Periastron通道周围的ηCAR中的高能(VHE; e> 100 GEV)γ射线发射,并具有地面高能立体镜系统(H.E.S.S.)。方法。 H.E.S.S.观察到η汽车周围的区域在轨道相位p = 0.78-1.10之间,在p {\ ot} 0.95和p {\ ot ot} 1.10(假设2023天的时间)下进行近近采样。需要优化的硬件设置以及对数据减少,重建和信号选择的调整,以考虑并考虑ηCAR视野中的强,扩展和不均匀的夜空背景(NSB)。量身定制的运行式蒙特卡洛模拟(RWS)需要准确处理仪器响应函数中NSB光子的额外噪声。结果。 H.E.S.S.从X射线曲线最小值前后不久和之后检测到从ηCar的方向上检测到的VHEγ射线发射。使用RWS提供的点扩展函数,重建的信号是点状的,并且频谱最好由功率定律描述。 VHEγ射线中的总体通量和光谱指数在脑周围和之后的统计和系统误差中一致。 γ射线频谱延伸至至少约400 GEV。这意味着在0.5高斯发射区域的松性场景中最大的磁场。在H.E.S.S.中未检测到相锁的通量变化的指示。数据。
Aims. Colliding wind binary systems have long been suspected to be high-energy (HE; 100 MeV < E < 100 GeV) γ-ray emitters. η Car is the most prominent member of this object class and is confirmed to emit phase-locked HE γ rays from hundreds of MeV to ~100 GeV energies. This work aims to search for and characterise the very-high-energy (VHE; E >100 GeV) γ-ray emission from η Car around the last periastron passage in 2014 with the ground-based High Energy Stereoscopic System (H.E.S.S.). Methods. The region around η Car was observed with H.E.S.S. between orbital phase p = 0.78 - 1.10, with a closer sampling at p {\approx} 0.95 and p {\approx} 1.10 (assuming a period of 2023 days). Optimised hardware settings as well as adjustments to the data reduction, reconstruction, and signal selection were needed to suppress and take into account the strong, extended, and inhomogeneous night sky background (NSB) in the η Car field of view. Tailored run-wise Monte-Carlo simulations (RWS) were required to accurately treat the additional noise from NSB photons in the instrument response functions. Results. H.E.S.S. detected VHE γ-ray emission from the direction of η Car shortly before and after the minimum in the X-ray light-curve close to periastron. Using the point spread function provided by RWS, the reconstructed signal is point-like and the spectrum is best described by a power law. The overall flux and spectral index in VHE γ rays agree within statistical and systematic errors before and after periastron. The γ-ray spectrum extends up to at least ~400 GeV. This implies a maximum magnetic field in a leptonic scenario in the emission region of 0.5 Gauss. No indication for phase-locked flux variations is detected in the H.E.S.S. data.