Structured Jet Model for Multiwavelength Observations of the Jetted Tidal Disruption Event AT 2022cmc

TL;DR

This paper presents a multizone relativistic jet model for the tidal disruption event AT 2022cmc, explaining its multiwavelength emissions through different jet components and their evolution influenced by energy injection and external density.

Contribution

It introduces a novel multizone jet model with relativistic jets of different Lorentz factors to interpret complex TDE observations, including X-ray and radio emissions.

Findings

X-ray spectra explained by reverse shock synchrotron emission of the fast jet.

Radio emissions attributed to forward shock of the slow jet.

Jet evolution significantly affected by energy injection rates.

Abstract

AT 2022cmc is a recently documented tidal disruption event (TDE) that exhibits a luminous jet, accompanied by fast-declining X-ray and long-lasting radio/millimeter emission. Motivated by the distinct spectral and temporal signatures between X-ray and radio observations, we propose a multizone model involving relativistic jets with different Lorentz factors. We systematically study the evolution of the faster and slower jets in an external density profile, considering the continuous energy injection rate associated with the time-dependent accretion rates before and after the mass fallback time. We investigate time-dependent multiwavelength emission from both the forward shock and reverse shock regions of the fast and slow jets, in a self-consistent manner. Our analysis demonstrates that the energy injection rate can significantly impact the jet evolution and subsequently influence the lightcurves. We find that the X-ray spectra and lightcurves can be described by the electron synchrotron emission from the reverse shock of the faster jet, in which the late-time X-ray upper limits, extending to 400 days after the disruption, could be interpreted as the jet break steepening. Meanwhile, the radio observations can be interpreted as a result of synchrotron emissions from the forward shock region of the slower jet. We also discuss prospects for testing the model with current and future observations.