Geometric masking in AGN jets and its implications for unification and blazar physics

Abstract

I explore the theoretical implications of the Geometric Masking scenario for AGN Unification and the blazar sequence. In PKS 2155$-$304, GeV spectral hardening appears locked to its $\sim 1.7$ yr quasi-periodic oscillation trough, suggesting high-flux states are dominated by a soft, geometrically amplified envelope that masks an underlying hard core. While this foundational mechanism builds on observations of coexisting emission regions (Madero & Domínguez 2026) and phase-locked spectral hardening (Domínguez et al. 2026), here I propose hypothetical extensions that fall outside the scope of those works. I propose that Doppler boosting preferentially enhances this soft component in closely aligned jets. This visibility bias could extend AGN Unification and introduce a geometric modulation layer to the blazar sequence. Under this speculative framework, low-flux states represent windows of geometric transparency, and misaligned systems act as naturally unmasked laboratories. Consequently, the intrinsic duty cycle of extreme acceleration in AGN jets may be higher than inferred from flux-selected observations.

arXiv commentPublished in Research Notes of the American Astronomical Society