HEASA 2026 (29 Sep - 02 Oct)

Session

AGN 2

30 Sept 2026, 10:30

Description

Chair: Markus Boettcher

62. From snapshots to movies, in colour, with the Event Horizon Telescope

Sera Markoff (University of Amsterdam)

30/09/2026, 10:30

Active Galactic Nuclei

Invited Talk

The Event Horizon Telescope (EHT) is a global mm-VLBI array (230 GHz) that captured the first images of two supermassive black holes, M87 and Sgr A* in 2017. Since then EHT has been expanding with the addition of several new telescopes, as well as a new observing frequency (345 GHz). During its typically annual campaign of ~1-2 weeks, EHT observes the horizon sources as well as a selection...

67. RADIO AND GAMMA–RAY VARIABILITY STUDY OF A SAMPLE OF BLAZARS

DANIEL NGHINYEKWA (University of Namibia)

30/09/2026, 11:01

Active Galactic Nuclei

Contributed Talk

This study aimed to assess existing multi-wavelength analysis techniques and identify statistical mea- sures that effectively characterize temporal variability of blazars. The data used in the analysis were retrieved from VizieR consisting of three catalogs (VLBA, Effelsberg, and Fermi–LAT observations). From these, a sample of 15 common blazars was selected and their light curves were...

9. Revisiting the AGN discovered in the Fairall survey

Hartmut Winkler (University of Johannesburg)

30/09/2026, 11:14

Active Galactic Nuclei

Contributed Talk

Fifty years ago local astronomer Tony Fairall initiated what was originally intended as a southern sky counterpart of the Markarian survey. Markarian's observations had led to the identification of many new Active Galactic Nuclei. One of Fairall's first discoveries was a bright nearby quasar that has become known as "Fairall 9". While most of the over 1500 sources added to the Fairall lists in...

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

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

30/09/2026, 11:27

Active Galactic Nuclei

Contributed Talk

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...

16. Long‑term multi‑wavelength SED and variability modeling of the HSP BL Lac PKS 2155-304

Ms Shruti Mukherjee (The University of the Free State)

30/09/2026, 11:40

Active Galactic Nuclei

Contributed Talk

PKS 2155-304 is a nearby high‑synchrotron‑peaked (HSP) BL Lac blazar at redshift z ≈ 0.116, and a benchmark source for studying multiwavelength variability in relativistic jets. In this work, we present a time‑dependent modeling study of its spectral energy distributions (SEDs) across the electromagnetic spectrum, using data from H.E.S.S. (very‑high‑energy gamma rays, 2003-2016), Fermi‑LAT...