论文标题
非常高的能量平坦频谱无线电类星体候选
Very High Energy Flat Spectral Radio Quasar Candidates
论文作者
论文摘要
外乳外背景光(EBL)对非常高能量(VHE)光子的衰减阻止了高红移平坦频谱无线电类星体(FSRQ)的观察。但是,VHE光谱指数与源红移的相关性表明,EBL强度可能小于预测。这种偏差可以对宇宙对伽马射线的不透明度产生新的约束。因此,与现有EBL模型预测的FSRQ相比,更多的FSRQ可能超过即将到来的VHE望远镜的灵敏度。为了说明索引红移相关性预测的较低的EBL强度,我们将依赖红移的校正因子引入了从常用宇宙学EBL模型估计的不透明度。考虑到这种修改的不透明度,我们通过线性推断\ emph {fermi}伽玛射线频谱在10 GEV到VHE制度来识别合理的VHE FSRQ候选者。我们的研究表明,在\ emph {fermi}第四目录数据2(4FGL-DR2)中报道的744个FSRQ中,Cherenkov望远镜阵列阵列(CTAO)可以检测到32个FSRQ。由于FSRQ被证明是高度可变的,因此我们假设一种场景,即平均\ emph {fermi}γ射线通量增加了10倍,这预计CTAO可以检测到的额外的90 FSRQ。
The attenuation of very high energy (VHE) photons by the extragalactic background light (EBL) prevents the observation of high redshift flat spectrum radio quasars (FSRQs). However, the correlation of VHE spectral index with source redshift suggests that EBL intensity may be less than what is predicted. This deviation can draw new constraints on opacity of the universe to VHE gamma-rays. Therefore, more FSRQs may fall above the sensitivity of the forthcoming VHE telescopes than the ones predicted by the existing EBL models. In order to account for the lower EBL intensity predicted by the index-redshift correlation, we introduce a redshift dependent correction factor to the opacity estimated from commonly used cosmological EBL model. Considering this modified opacity, we identify the plausible VHE FSRQ candidates by linearly extrapolating the \emph{Fermi} gamma-ray spectrum at 10 GeV to VHE regime. Our study suggests among 744 FSRQs reported in \emph{Fermi} fourth catalog-Data release 2 (4FGL-DR2), 32 FSRQs will be detectable by Cherenkov Telescope Array Observatory (CTAO). Since the FSRQS are proven to be highly variable, we assume a scenario where the average \emph{Fermi} gamma-ray flux increases by a factor of 10 and this predicts additional 90 FSRQs that can be detected by CTAO.