论文标题
用HAWC探测伴层次的中红外背景
Probing the extragalactic mid-infrared background with HAWC
论文作者
论文摘要
自重组时期以来，核外背景光（EBL）包含核和恒星和紧凑物体的增生过程发出的所有辐射。直接测量EBL密度是具有挑战性的，尤其是在近红外波段中，这主要是由于黄道带前景。取而代之的是，伽玛射线天文学提供了通过研究远处大爆炸的非常高能量（VHE：$> $ 100 GEV）光谱中伽马射线吸收的影响，从而使EBL间接设定限制。高空水Cherenkov伽马射线天文台（HAWC）是对伽马射线敏感的少数工具之一，其能量以上是10 TEV。这提供了在近/中期区域探测EBL的机会：$λ$ = 1 $μ$ m -100 $μ$ m。在这项研究中，我们将出于物理动机的发射模型拟合到费米大面积望远镜（LAT）GEV数据，以推断大麻的内在TEV光谱。然后，我们通过比较和测试了两个大型弹药的吸收光谱和HAWC外静脉外观测的一致性，模拟了不同随机生成的EBL模型形状的大量吸收光谱，并计算EBL强度空间中的贝叶斯可信条带。所得条带与当前的EBL下限和上限一致，显示出较高波长值$λ> 10 \，μ$ m的向下趋势在先前的测量中也观察到。
The extragalactic background light (EBL) contains all the radiation emitted by nuclear and accretion processes in stars and compact objects since the epoch of recombination. Measuring the EBL density directly is challenging, especially in the near- to far-infrared waveband, mainly due to the zodiacal light foreground. Instead, gamma-ray astronomy offers the possibility to indirectly set limits on the EBL by studying the effects of gamma-ray absorption in the very high energy (VHE:$>$100 GeV) spectra of distant blazars. The High Altitude Water Cherenkov gamma ray observatory (HAWC) is one of the few instruments sensitive to gamma rays with energies above 10 TeV. This offers the opportunity to probe the EBL in the near/mid IR region: $λ$ = 1 $μ$m - 100 $μ$m. In this study, we fit physically motivated emission models to Fermi Large Area Telescope (LAT) GeV data to extrapolate the intrinsic TeV spectra of blazars. We then simulate a large number of absorbed spectra for different randomly generated EBL model shapes and calculate Bayesian credible bands in the EBL intensity space by comparing and testing the agreement between the absorbed spectra and HAWC extragalactic observations of two blazars. The resulting bands are in agreement with current EBL lower and upper limits, showing a downward trend towards higher wavelength values $λ>10\, μ$m also observed in previous measurements.
