Year: 2025
Type: article
Abstract: In this study, we analyze the ∼16 yr Fermi-Large Area Telescope data of 160 blazars consisting of 92 flat-spectrum radio quasars (FSRQs), 64 BL Lacertae (BL Lac)–type objects, and 4 blazar-candidates-of-unknown-type objects, and investigate their spectral variation. By fitting a linear model (y = kx + b) to the monthly binned flux-index plots, we find that most of the FSRQs (∼89%) display a harder-when-brighter trend (k > 0), while the majority of BL Lac–type objects (∼64%) exhibit a softer-when-brighter trend (k < 0). By plotting their slope (k) versus their variability index and inverse Compton (IC) peak frequency, we find a moderate positive correlation between k and the variability index and a moderate negative correlation between k and the IC peak frequency, which we name as the gamma-ray variability sequence of blazars. Additionally, eight blazars may not follow the linear variation trend, particularly in PKS 0537-441, AP Librae, and PKS 1510-089. Additional very-high-energy gamma-ray emission components may be the cause of the nonlinear variation trend.
Source: The Astrophysical Journal
Authors: Junhao Deng, Yunguo Jiang
Institution: Shandong University
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
Awards: G2376417518, 多波段相关性和偏振对耀变体辐射区和光变机制的限制
OpenAlex ID: W4409464535