A Multiwavelength Study of a Long-Duration VHE Flare from BL Lacertae with VERITAS

arXiv:2607.15435 · astro-ph.HE · Submitted 2026-07-16 · Read on arXiv

Atreya Acharyya, Avery Archer, Priyadarshini Bangale, Joshua Bartkoske, Wystan Benbow, James Buckley, Yu Chen, Jodi Christiansen, Alisha Chromey, Anne Duerr, Manel Errando, Miguel Escobar Godoy, Juan Escudero Pedrosa, Abe Falcone, Sydney Feldman, Qi Feng, Simon Filbert, Lucy Fortson, Amy Furniss, William Hanlon, Olivier Hervet, Claire Hinrichs, Jamie Holder, Zach Hughes, Thomas Humensky, Weidong Jin, Madalyn Johnson, Philip Kaaret, Mary P. Kertzman, Maria Kherlakian, Tobias Kleiner, Nikolas Korzoun, Sanchari Kundu, Mark Lang, Matthew Lundy, Eileen Meyer, John Millis, Connor Mooney, Patrick Moriarty, Reshmi Mukherjee, Wenmeng Ning, Rene A. Ong, Ashwani Pandey, Martin Pohl, Elisa Pueschel, John Quinn, Pazit Rabinowitz, Kenneth J. Ragan, Paul Reynolds, Deivid Ribeiro, Leandro Rizk, Emmet Thomas Roache, Iftach Sadeh, Alberto Sadun, Lab Saha, Glenn Sembroski, Ruo Shang, Megan Splettstoesser, Donggeun Tak, Anjana Talluri, James Tucci, Janeth Valverde, David Williams, Sam Wong, Margo Aller, Masoud Asadi-Zeydabadi, Ryan Hickox, Svetlana Jorstad, Sebastian Kiehlmann, Piatra Lusen, Allen Marscher, Walter Max-Moerbeck, Philipe De La Parra, Anthony Readhead, Katie Riley

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astro-ph.HE

Submitted: 2026-07-16

Comments: 19 pages, 8 figures. Accepted for publication in the Astrophysical Journal (ApJ)

Code: https://github.com/Ohervet/Bjet

License: http://creativecommons.org/licenses/by/4.0/

The gist: We report the first observations of a long-duration very-high-energy (VHE; E > 100 GeV) flare from BL Lacertae (VER J2202+422), taken with the Very Energetic Radiation Imaging Telescope Array System

Terminology

Abstract

We report the first observations of a long-duration very-high-energy (VHE; E > 100 GeV) flare from BL Lacertae (VER J2202+422), taken with the Very Energetic Radiation Imaging Telescope Array System (VERITAS). On October 15, 2022, the Fermi-Large Area Telescope (LAT) detected elevated GeV activity originating from this blazar. This triggered a multiwavelength campaign, which includes observations from VERITAS, Swift, NuSTAR, and select optical and radio observatories. VERITAS observed the source for a total of about 9.8 hours between September 1, 2022 and December 1, 2022. An analysis of these data yields a about 28 sigma detection of the source. While previously observed VHE flares from BL Lacertae have lasted on time-scales of minutes to days, VERITAS continued to detect flaring activity from the source for over a month (about 40 days) after the original flaring activity was detected with Fermi-LAT. Broadband spectral modeling shows that a synchrotron self-Compton (SSC) model with an external inverse-Compton (EC) component is preferred over a one-zone SSC model.

Sources

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