arXiv subjects

Qiu-Li Wang

Publications and source records attributed to Qiu-Li Wang.

3 recordsLinked to original sources

arXiv2026

The Double-Burst Nature and Early Afterglow Evolution of Long GRB 110801A

We present a comprehensive temporal and spectral analysis of the long-duration gamma-ray burst GRB 110801A, utilizing multi-band data from the Neil Gehrels Swift Observatory and ground-based telescopes. The $γ$-ray emission exhibits a distinct two-episode (``double-burst'') structure. Rapid follow-up observations in the optical and X-ray bands provide full coverage of the second burst. The optical light curve begins to rise approximately 135 s after the trigger, significantly preceding the second emission episode observed in X-rays and $γ$-rays at $\sim 320$ s. This chromatic behavior suggests different physical origins for the optical and high-energy emissions. Joint broadband spectral fitting (optical to $γ$-rays) during the second episode reveals that a two-component model, consisting of a power-law plus a Band function, provides a superior fit compared to single-component models. We interpret the power-law component as the afterglow of the first burst (dominating the optical band), while the Band component is attributed to the prompt emission of the second burst (dominating the high-energy bands). A physical synchrotron model is also found to be a viable candidate to explain the high-energy emission. Regarding the afterglow, the early optical light curve displays a sharp transition from a rise of $\sim t^{2.5}$ to $\sim t^{6.5}$, which is well-explained by a scenario involving both reverse shock (RS) and forward shock (FS) components. We constrain the key physical parameters of the burst, deriving an initial Lorentz factor $Γ_0 \sim 60$, a jet half-opening angle $θ_j \sim 0.09$, and an isotropic kinetic energy $E_{\rm k,iso} \sim 10^{54.8}$ erg.

astro-ph.HE↗

arXiv2025

GRB 240825A: Early Reverse Shock and Its Physical Implications

Early multiwavelength observations offer crucial insights into the nature of the relativistic jets responsible for gamma-ray bursts and their interaction with the surrounding medium.We present data of GRB 240825A from 17 space- and ground-based telescopes/instruments, covering wavelengths from NIR/optical to X-ray and GeV, and spanning from the prompt emission to the afterglow phase triggered by Swift and Fermi. The early afterglow observations were carried out by SVOM/C-GFT, and spectroscopic observations of the afterglow by GTC, VLT, and TNG determined the redshift of the burst ($z = 0.659$) later.A comprehensive analysis of the prompt emission spectrum observed by Swift-BAT and Fermi-GBM/LAT reveals a rare and significant high-energy cutoff at ~76 MeV. Assuming this cutoff is due to $γγ$ absorption allows us to place an upper limit on the initial Lorentz factor, $Γ_0 < 245$. The optical/NIR and GeV afterglow light curves be described by the standard external shock model, with early-time emission dominated by a reverse shock (RS) and a subsequent transition to forward shock (FS) emission. Our afterglow modelling yields a consistent estimate of the initial Lorentz factor ($Γ_{\rm 0} \sim 234$). Furthermore, the RS-to-FS magnetic field ratio ($\mathcal{R}_B \sim 302$) indicates that the reverse shock region is significantly more magnetized than the FS region. An isotropic-equivalent kinetic energy of $E_{\text{k,iso}} = 5.25 \times 10^{54}$ erg is derived, and the corresponding $γ$-ray radiation efficiency is estimated to be $η_γ$ = 3.1%. On the other hand, the standard afterglow model can not reproduce the X-ray light curve of GRB 240825A, calling for improved models to characterize all multiwavelength data.

astro-ph.HE↗

arXiv2025

GRB 241030A: a prompt thermal X-ray emission component and diverse origin of the very early UVOT WHITE and U band emission

We present a detailed analysis of the long-duration GRB 241030A detected by {\it Swift}. Thanks to the rapid response of XRT and UVOT, the strongest part of the prompt emission of GRB 241030A has been well measured simultaneously from optical to hard X-ray band. The time-resolved WHITE band emission shows strong variability, largely tracing the activity of the prompt gamma-ray emission, may be produced by internal shocks too. The joint analysis of the XRT and BAT data reveals the presence of a thermal component with a temperature of a few keV, which can be interpreted as the photosphere radiation, and the upper limit of the Lorentz factor of this region is found to range between approximately 20 and 80. The time-resolved analysis of the initial U-band exposure data yields a very rapid rise ($ \sim t^{5.3}$) with a bright peak reaching 13.6 AB magnitude around 410 seconds, which is most likely attributed to the onset of the external shock emission. The richness and fineness of early observational data have made this burst a unique sample for studying the various radiation mechanisms of gamma-ray bursts.

astro-ph.HE↗