Narrow-line Seyfert 1 galaxies (NLSy1s) are a well established class of $\gamma$ -ray sources, showing the presence of a jet like the more common flat-spectrum radio quasars. The evidence of $\gamma$ -ray emission poses the issue of the location of the $\gamma$ -ray emitting zone and of the contribution of the $\gamma$ - $\gamma$ absorption within the broad-line region (BLR), since such objects have been detected by Fermi-LAT in the MeV-GeV energy range but not by imaging atmospheric Cherenkov telescopes beyond 100 GeV. We discuss how the spectral properties of three NLSy1s (SBS 0846+513, PMN J0948+0022, and PKS 1502+036) derived from the Fermi Large Area Telescope Fourth Source Catalog (4FGL) compared with theoretical models based on the observed properties of the BLR. In particular, we focus on the question on how simple power-law spectral models and log-parabolic ones could be disentangled in $\gamma$ -ray narrow-line Seyfert 1 galaxies by means of current Fermi-LAT or future imaging atmospheric Cherenkov telescopes data. We found that the only possibility for a log-parabolic model to mimic a power-law model in the energy band above $E\sim 100$ GeV is to have a very small value of the curvature parameter $\beta \sim 0.05$ .

中文翻译：

---

窄线赛弗1星系中对数抛物线光谱模型的高能和极高能约束

窄线塞弗1星系（NLSy1s）是一类公认的 $\gamma$ 射线源，表明像更常见的平谱无线电类星体一样存在喷射流。的证据 $\gamma$ 射线发射带来了问题的位置 $\gamma$ 射线发射区以及 $\gamma$ -- $\gamma$ Fermi-LAT已在MeV-GeV能量范围内检测到了这些物体，但没有通过对超过100 GeV的大气Cherenkov望远镜成像而检测到了这些物体。我们讨论了根据费米大面积望远镜第四源目录（4FGL）得出的三个NLSy1s（SBS 0846 + 513，PMN J0948 + 0022和PKS 1502 + 036）的光谱特性与理论模型之间的比较，该模型基于理论上的观测特性BLR。尤其是，我们关注的问题是如何简单地分解幂律谱模型和对数抛物线模型 $\gamma$ 当前的费米-拉特望远镜或未来成像的大气切伦科夫望远镜的数据，可以使Seyfert 1星系产生X射线窄线。我们发现对数抛物线模型模仿上面能量带中的幂律模型的唯一可能性 $Ë〜100$ GeV将具有非常小的曲率参数值 $\beta 〜0.05$ 。