The Estimation of Fundamental Physics Parameters for Fermi-LAT Blazars

Abstract

Aiming to delineate the physical framework of blazars, we present an effective method to estimate four important parameters based on the idea proposed by Becker & Kafatos, including the upper limit of central black hole mass M, the Doppler factor δ, the distance along the axis to the site of the γ-ray production d (which then can be transformed into the location of γ-ray-emitting region R γ ) and the propagation angle with respect to the axis of the accretion disk Φ. To do so, we adopt an identical sample with 809 Fermi-LAT-detected blazars which had been compiled in Pei et al. These four derived parameters stepping onto the stage may shed new light on our knowledge regarding γ-ray blazars. With regard to the paper of Becker & Kafatos, we obtain several new perspectives, mainly in (1) putting forward an updated demarcation between BL Lacs and FSRQs based on the relation between broad-line region luminosity and disk luminosity both measured in Eddington units, i.e., L disk/L Edd = 4.68 × 10−3, indicating that there are some differences between BL Lacs and FSRQs on the accretion power in the disk; (2) proposing that there is a so-called “appareling zone,” a potential transition field between BL Lacs and FSRQs where the changing-look blazars perhaps reside; (3) the location of γ-ray emission region is principally constrained outside the broad-line region, and for some BL Lacs are also away from the dusty molecular torus, which means the importance of emission components in the jet.

An Extensive Study of Blazar Broad Emission Line: Changing-look Blazars and the Baldwin Effect

“…It is that the changing-look blazars mostly lie above the dividing lines proposed by Ghisellini et al (2011) andSbarrato et al (2012). Pei et al (2022) studied the correlation L Disk /L Edd vs L γ /L Edd , assuming L Disk = 10L BLR , and it was clearly shown in Figure 5 of their work that the FSRQs and the changing-look blazars have larger accretion ratios than the BL Lac objects. They have proposed an "appareling zone," 2.0 × 10 −4 L BLR /L Edd 8.5 × 10 −3 , to select changing-look blazar candidates, and we found that there are 46 (taking 82.1%) changing-look blazars in our sample that lie in this zone.…”

An extensive study of blazar broad emission line: Changing-look blazars and Baldwin effect

“…It is that the 'Changing-look' blazars mostly lie above the dividing lines proposed by Ghisellini et al (2011) and Sbarrato et al (2012). Pei et al (2022) studied the correlation L Disk /L Edd vs L γ /L Edd , assuming L Disk = 10L BLR , and it was clearly shown in Figure 5 of their work that the FSRQs and the 'Changing-look' blazars have larger accretion ratio than the BL Lacs. They have proposed an 'appareling zone', 2.0 × 10 −4 ≤ L BLR /L Edd ≤ 8.5 × 10 −3 , to select 'Changing-look' blazars candidates, and we found that there are 46 (taking 82.1%) 'Changing-look' blazars in our sample that lie in this zone.…”

Characterizing the Emission Region Properties of Blazars

“…In this work, we have focused our research on the location of the blazar emission region. We applied a timescale of 1 day, which was suggested by Nalewajko (2013); as a typical variability timescale in the source frame in the Fermi γ-ray band, this timescale has been used in many works (e.g., Ghisellini et al 1998;Fan et al 2013;Nalewajko 2013;Chen 2018;Pei et al 2022). One can set an upper limit on the emission region size via inequality (6), thus its distance from the SMBH can be estimated via Equation ( 7).…”