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BL Lacs are one subclass of blazars with highly energetic γ -ray emission, which is strongly boosted by a relativistic beaming effect. The latest catalogue of the 10 years of Fermi/LAT data (Abdollahi et al. 2020) and the γ -ray Doppler factors in Pei et al. (2020) provide us with a large BL Lac sample to study their jet emission morphologies and intrinsic properties. In this paper, we collected a sample of 294 Fermi BL Lacs and probed the correlations between the γ -ray emissions and luminosity distances. Our analyses give following conclusions: (1) the observed γ -ray emissions are really boosted by the γ -ray Doppler factor, and the intrinsic γ -ray emissions are closely correlated with luminosity distances. (2) the morphology of jet emissions for HBLs may be continuous, while that for IBLs may be the case of a moving sphere in the γ -ray bands. [ABSTRACT FROM AUTHOR]

Searching for as yet undetected γ -ray sources is one of the main stated goals of the Fermi Large Area Telescope Collaboration. In this paper, we explore the capability of a filtering method based on a finite mixture of von Mises–Fisher distributions. The proposed procedure is specifically designed to handle data with support on the unit sphere. The assumption of a parametric model for each high energy emitting source allows us to derive an explicit expression for both the direction of the sources and their angular resolutions. The corresponding measures are based on the directional mean and the quantiles of the single mixture components. Sound criteria of model selection can provide an automatic way to determine the number of detected sources. Additionally, a likelihood-ratio test is developed to evaluate their significance. The procedure is tested on simulated data sets of photon emissions from high energy sources within the energy range [ 10 − 1 , 000 ] GeV . A real data example consisting of a sample of the Fermi LAT data collected over a period of about 7.2 years within the energy range [ 10 − 1 , 000 ] GeV , in a subregion of the γ -ray sky, is furthermore provided. [ABSTRACT FROM AUTHOR]

In this paper, multiwavelength chromatic luminosity at radio (logLR), optical (logLO), X-ray (logLX), and γ-rays (logLγ) for a sample of 442 Fermi blazars with known redshifts are collected from Fan et al. (2016), to study the correlations between the γ-rays and the low-energy bands using a multiple linear regression analysis. In this way, we can see which band is more important for the γ-ray emissions. Mutual correlation analysis is also used to discuss the correlations between the γ-ray and the low energy bands for the whole sample and subclasses. We come to following conclusions: The multiple linear correlation indicates that the γ-rays are correlated with the radio, optical and the X-ray emissions for the whole sample and the subclasses of flat spectrum radio quasars (FSRQs) and BL Lac objects (BL Lacs), the correlation between the γ-rays and the radio emissions is the strongest one.For BL Lacs, the optical emissions are more important than the X-rays for the γ-rays, while the X-ray emissions are more important than optical ones in FSRQs.The γ-ray emissions in HBL are from an synchrotron self-Compton, while those in FSRQs may be from external Compton and synchrotron self-Compton as well. [ABSTRACT FROM AUTHOR]