AI 中文总结
本研究提出基于物理的多成分光谱拟合管线，分析SDSS-V中费米探测的耀变体，修正了SDSS的误分类，提升了红移估计精度，挑战了传统耀变体二元分类。
AI 中文摘要
斯隆数字巡天（SDSS）的自动光谱处理管线因模板库中缺乏非热喷流连续谱成分，系统地将以喷流为主的耀变体分类为银河系恒星、星系或典型类星体。本研究提出一种新的、基于物理的多成分光谱拟合管线，将其应用于SDSS-V数据发布20光谱数据库中746个费米/4FGL-DR4 γ射线源的光学对应体，得到707个拟合良好的耀变体候选体，这些候选体以幂律+星系（59.4%）、幂律+发射线（22.6%）和幂律+类星体（15.0%）模型族为主。独立的WISE红外测光证实，SDSS最初误分类为银河系恒星的88个源中，96.6%处于典型耀变体区域，其中90.9%被重新分类为蝎虎座BL型天体（BL Lac）候选体，证明了新管线的成功。新分类方案自然恢复了已知的BL Lac与平谱射电类星体（FSRQ）候选体之间的宇宙学分离，以及γ射线光度中位数约一个数量级的分离。我们将红移估计与第三费米-LAT高能源目录（3FHL）中的111个源的验证样本进行比较，发现与SDSS管线相比，灾难性失败减少了10.4%（η=0.387 vs 0.432）。等效宽度分析在总体水平上验证了传统的|EW|=5埃分类边界（BL Lac：4.47±0.15埃；FSRQ：22.86±0.86埃），尽管49.5%的单个BL Lac候选体超过该阈值，且51.4%同时显示发射和吸收特征。这种混合挑战了传统的耀变体二元分类，表明耀变体性质具有更连续的物理描述。
英文摘要
The automated spectroscopic pipeline of the Sloan Digital Sky Survey (SDSS) systematically assigns Galactic star, galaxy, or typical quasar classifications to jet-dominated blazars, owing to the absence of a non-thermal jet continuum component in its template library. In this study, we present a new, physically motivated, multi-component spectral fitting pipeline that we apply to 746 optical counterparts of Fermi/4FGL-DR4 $γ$-ray sources in the SDSS-V Data Release 20 spectroscopic database, yielding 707 well-fitted blazar candidates dominated by Power-law+Galaxy (59.4%), Power-law+Lines (22.6%), and Power-law+QSO (15.0%) model families. Independent WISE infrared (IR) photometry confirms that 96.6% of the 88 sources originally misclassified as Galactic stars by SDSS fall within the canonical blazar region, with 90.9% reclassified as BL Lacertae object (BL Lac) candidates, demonstrating the success of our new pipeline. The new classification scheme naturally recovers the known cosmological separation between BL Lac and Flat Spectrum Radio Quasar (FSRQ) candidates and a separation of approximately one order of magnitude in median $γ$-ray luminosity. We compare our redshift estimates to a validation sample of 111 sources in the Third Fermi-LAT Catalogue of High-Energy Sources (3FHL), finding a 10.4% reduction in catastrophic failures ($η= 0.387$ vs 0.432) over the SDSS pipeline. The equivalent width analysis validates the traditional |EW| = 5 Ang classification boundary at the population level (BL Lac: 4.47 $\pm$ 0.15 Ang; FSRQ: 22.86 $\pm$ 0.86 Ang), although 49.5% of individual BL Lac candidates exceed this threshold and 51.4% show simultaneous emission and absorption features. This hybrid population challenges the traditional binary blazar classification and points towards a more physically continuous description of blazar properties.
Comments34 pages, 17 figures plus appendices. Submitted to MNRAS. Catalogue available as SDSS DR20 Value-Added Catalogue https://www.sdss.org/dr20/data_access/value-added-catalogs/?vac_id=10034 Accompanied visualization python package tool https://github.com/minlowie/Blazar-Analysis-Pipeline
