arXiv subjects

Jiang-Chuan Tuo

Publications and source records attributed to Jiang-Chuan Tuo.

3 recordsLinked to original sources

arXiv2026

Jet-Structure Imprint on the Curvature Tail of Gamma-Ray Burst Prompt Emission

Even though the prompt emission of gamma-ray bursts (GRBs) is highly beamed, high-latitude emission still produces a distinct light curve break after the intrinsic emission ceases and the edge of the jet comes into view. This curvature effect offers a direct probe of the jet structure during the prompt phase. To uncover the geometric structure of the GRB jet encoded in the prompt light-curve evolution, we develop a numerical model that calculates synchrotron light curves from structured jets to interpret the observed break. We apply this model to the prompt emission of GRB 230307A, which displays a rare late-time break. Our analysis demonstrates that simple spherical outflow and top-hat jet models are inadequate to reproduce the light curve. Instead, the observations are best described by a power-law wing jet with a uniform core ($θ_{\rm core}=0.0147$ rad) and a surrounding power-law wing. Our results demonstrate that the break in late-time prompt emission can be a powerful diagnostic of GRB jet structure.

astro-ph.HE↗

arXiv2025

In-orbit background and sky survey simulation study of POLAR-2/LPD

The Low-Energy X-ray Polarization Detector (LPD) is one of the payloads in the POLAR-2 experiment, designed as an external payload for the China Space Station (CSS) deployment in early 2024. LPD is specifically designed to observe the polarization of Gamma-Ray Bursts (GRBs) prompt emission in the energy range of 2-10 keV, with a wide field of view (FoV) of 90 degrees in preliminary design. This observation is achieved using an array of X-ray photoelectric polarimeters based on gas pixel detectors. Due to the wide FoV configuration, the in-orbit background count rate in the soft X-ray range is high, while GRBs themselves also exhibit a high flux in this energy band. In order to assess the contribution of various background components to the total count rate, we conducted detailed simulations using the GEANT4 C++ package. Our simulations encompassed the main interactions within the instrument materials and provided insights into various background components within the wide FoV scheme. The simulation results reveal that among the background components, the primary contributors are the cosmic X-ray background (CXB) and bright X-ray sources. The total background count rate of LPD, after applying the charged particle background rejection algorithm, is approximately 0.55 counts/cm^2/s on average, and it varies with the detector's orbit and pointing direction. Furthermore, we performed comprehensive simulations and comparative analyses of the CXB and X-ray bright sources under different FoVs and detector pointings. These analyses provide valuable insights into the background characteristic for soft X-ray polarimeter with wide FoV.

astro-ph.IM↗

arXiv2024

Polarization degree of magnetic field structure changes caused by random magnetic field in Gamma-ray Burst

In a Poynting-flux-dominated (PFD) jet that exhibits an ordered magnetic field, a transition towards turbulence and magnetic disorder follows after magnetic reconnection and energy dissipation during the prompt emission phase. In this process, the configuration of the magnetic field evolves with time, rendering it impossible to entirely categorize the magnetic field as ordered. Therefore, we assumed a crude model that incorporates a random magnetic field and an ordered magnetic field, and takes into account the proportionality of the random magnetic field strength to the ordered magnetic field, in order to compute the polarization degree (PD) curve for an individual pulse. It has been discovered that the random magnetic field has a significant impact on the PD results of the low-energy X-ray. In an ordered magnetic field, the X-ray segment maintains a significant PD compared to those in the hundreds of keV and MeV ranges even after electron injection ceases, this making PD easier to detect by polarimetry. However, when the random magnetic field is introduced, the low-energy and high-energy PDs exhibit a similar trend, with the X-ray PD being lower than that of the high-energy segment. Of course, this is related to the rate of disorder in the magnetic field. Additionally, there is two rotation of the polarization angles (PAs) that were not present previously, and the rotation of the PA in the high-energy segment occurs slightly earlier. These results are unrelated to the structure of the ordered magnetic field.

astro-ph.HE↗