29 September 2026 to 3 October 2026
Africa/Johannesburg timezone

Exploring the Transitional Parameter Space of Blazars using Gamma-ray and X-ray Population Diagnostics

30 Sept 2026, 11:27
12m
Contributed Talk Active Galactic Nuclei AGN 2

Speaker

Dr Zahoor Malik (Department of Physics, University of the Free State, Bloemfontein, 9301, South Africa)

Description

We investigate the $\gamma$-ray and X-ray population properties of changing-look blazars (CLBs) using sources from the Fourth Fermi-LAT Source Catalog Data Release 4 (4FGL-DR4) together with X-ray information from the Living \textit{Swift} XRT Point Source (LSXPS) catalog. The CLB sample is compared with large populations of confirmed BL Lac objects (BLLs) and flat-spectrum radio quasars (FSRQs) using spectral, variability, and broadband properties. In the $\gamma$-ray parameter space, CLBs mainly occupy intermediate and overlap regions between the BLL and FSRQ populations. However, the centroid locations in different parameter planes, along with the PCA and UMAP projections, show that the CLB population lies closer to the FSRQ region. The X-ray analysis also shows a similar behavior, where the overall distribution of CLBs in the X-ray parameter space is found to be nearer to FSRQs than to BLLs. In addition, the X-ray/$\gamma$-ray coupling relations and random-forest classification probabilities are consistent with this trend. Overall, the results suggest that CLBs form a transitional population between the two main blazar subclasses while retaining characteristics closer to the FSRQ population.

Author

Dr Zahoor Malik (Department of Physics, University of the Free State, Bloemfontein, 9301, South Africa)

Co-authors

Dr Sikandar Akbar (Department of Physics University of Kashmir Srinagar 190006 India) Dr Zahir Shah (Manipal Centre for Natural Sciences Centre of Excellence Manipal Academy of Higher Education Manipal - 576104 India) Prof. B. van SOELEN (Department of Physics University of the Free State Bloemfontein 9301 South Africa)

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