GRB 120326 A是一个不寻常的伽马射线暴，它在X射线波段和光学波段都有一个相当长的平台和一个非常晚的再亮。光学和X射线光变曲线的相似行为表明它们可能有共同的起源。漫长的平台期从几百秒开始，到几万秒结束。后期再亮的峰值时间约为30000s。我们分析了能量注入模型的数值和解析解，考虑风环境和ISM环境的伽玛暴余辉。我们特别研究了注入开始时间、结束时间、星风密度（或环暴环境密度）和注入光度对余辉光变曲线形状的影响。我们发现，光变曲线在很大程度上受风模型中的参数。只有在风模型中，在后期也有一个“颠簸”。在风的情况下，有趣的是，能量注入的时间越长，再亮就越明显。我们还发现碰撞的峰值时间与星风密度有关。我们用晚期连续注入模型解释了GRB 120326A的异常余辉。该模型能很好地拟合观测数据，但我们发现，注入的时间尺度必须大于一万秒。这意味着中央引擎活动的时间尺度必须超过一万秒。这可以对伽玛暴的中心引擎提供有用的约束。我们考虑一颗新诞生的毫秒脉冲星，它具有强磁场作为中心引擎。另一方面，我们的研究结果表明，GRB 120326A的环暴环境很可能是恒星风。
英文摘要：
GRB 120326A is an unusual gamma-ray burst (GRB) which has a quite long plateau and a very late rebrightening both in X-ray and optical bands. The similar behavior of the optical and X-ray light curves suggests that they maybe have a common origin. The long plateau starts from several hundred seconds and ends at tens of thousands seconds. The peak time of the late rebrightening is about 30000 s. We analyze the energy injection model by means of numerical and analytical solutions, considering both the wind environment and ISM environment for GRB afterglows. We especially study the influence of the injection starting time, ending time, stellar wind density (or density of the circumburst environment), and injection luminosity on the shape of the afterglow light curves, respectively. We find that the light curve is largely affected by the parameters in the wind model. There is a "bump" at the late time only in the wind model too. In the wind case, it is interesting that the longer the energy injected, the more obvious the rebrightening will be. We also find the peak time of bump is determined by the stellar wind density. We use the late continuous injection model to interpret the unusual afterglow of GRB 120326A. The model can well fit the observational data, however, we find that the time scale of the injection must be larger than ten thousands seconds. This implies that the time scale of the central engine activity must be more than ten thousands seconds. This can give useful constraints on the central engine of GRBs. We consider a new born millisecond pulsar with strong magnetic field as the central engine. On the other hand, our results suggest that the circumburst environment of GRB 120326A is very likely a stellar wind.
We study the broadband radiation behavior of a kilonova ejecta-pulsar wind nebula (PWN) system. In this model, we jointly fit the observations of AT 2017gfo in UV-optical-IR bands and the late-time X-ray afterglow of GRB 170817A. Our work shows that a PWN powered by the remnant neutron star (NS) post GW170817 event could affect the optical transient AT 2017gfo and re-brighten the late-time X-ray afterglow of GRB 170817A. The PWN radiation will regulate the trend of future X-ray observations from a flattening to a steep decline until some other sources (e.g., a kilonova afterglow) become domina…
Long gamma-ray bursts give us the chance to study both their extreme physics and the star-forming galaxies in which they form. GRB 100418A, at a z = 0.6239, had a bright optical and radio afterglow, and a luminous star-forming host galaxy. This allowed us to study the radiation of the explosion as well as the interstellar medium of the host both in absorption and emission. We collected photometric data from radio to X-ray wavelengths to study the evolution of the afterglow and the contribution of a possible supernova and three X-shooter spectra obtained during the first 60 hr. The light curve …
We present a search for late-time rebrightening of radio emission from three supernovae (SNe) with associated gamma-ray bursts (GRBs). It has been previously proposed that the unusually energetic SNe associated with GRBs should enter the Sedov-Taylor phase decades after the stellar explosion, and this SN "remnant" emission will outshine the GRB radio afterglow and be detectable at significant distances. We place deep limits on the radio luminosity of GRB 980425/SN 1998bw, GRB 030329/SN 2003dh and GRB 060218/SN 2006aj, 10-18 years after explosion, with our deepest limit being $L_ν$ $< 4 \times …
Multi-epoch afterglow rebrightenings in GRB 250129A: Evidence for successive shock interactions
Université de la Côte d’Azur（蔚蓝海岸大学）；New York University Abu Dhabi（阿布扎比纽约大学）；Center for Astrophysics and Space Science (CASS), New York University Abu Dhabi（阿布扎比纽约大学天体物理学与空间科学中心）；IJCLab, Univ Paris-Saclay, CNRS/IN2P3（巴黎萨克雷大学IJCLab实验室）；Institute of Physics and Astronomy, Theoretical Astrophysics, University Potsdam（波茨坦大学物理与天文学研究所理论天体物理系）；Nikhef（尼赫夫国家粒子物理研究所）；Institute for Gravitational and Subatomic Physics (GRASP), Utrecht University（乌得勒支大学引力与亚原子物理研究所）；Purple Mountain Observatory, Chinese Academy of Sciences（中国科学院紫金山天文台）；Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México（墨西哥国立自治大学射电天文学与天体物理研究所）；Physics Department, Nazarbayev University（纳扎尔巴耶夫大学物理系）；Energetic Cosmos Laboratory, Nazarbayev University（纳扎尔巴耶夫大学高能宇宙实验室）；Université Paris-Saclay, Université Paris Cité, CEA, CNRS, AIM（巴黎萨克雷大学、巴黎西岱大学、法国原子能与替代能源委员会、法国国家科学研究中心）；E.Kharadze Georgian National Astrophysical Observatory（E.哈拉泽格鲁吉亚国家天文台）
GRB 250129A表现出多个晚期时间X射线和光学波段的再变亮现象，研究通过分析促发辐射和近红外数据，揭示后光再变亮可能由延迟碰撞刷新冲击波引起。
Afterglows of gamma-ray bursts often show flares, plateaus, and sudden intensity drops: these temporal features are difficult to explain as coming from the forward shock. We calculate radiative properties of early GRB afterglows with the dominant contribution from the reverse shock (RS) propagating in an ultra-relativistic (pulsar-like) wind produced by the long-lasting central engine. RS emission occurs in the fast cooling regime -- this ensures high radiative efficiency and allows fast intensity variations. We demonstrate that: (i) mild wind power, of the order of $\sim 10^{46}$ erg s$^{-1}$…
Short-duration GRB 250221A Afterglow Driven by Two-Component Jets from the merger of a compact star
Guangxi University（广西大学）；Nanjing University（南京大学）；Purple Mountain Observatory, Chinese Academy of Sciences（中国科学院紫金山天文台）；University of Science and Technology of China（中国科学技术大学）
GRB 250221A的后glow由双组分喷流模型解释，揭示了短持续时间GRB的双喷流机制及周际介质密度特征。
The central engine of gamma-ray bursts (GRBs) remains an open and forefront topic in the era of multimessenger astrophysics. The X-ray plateaus appear in some GRB afterglows, which are widely considered to originate from the spindown of magnetars. According to the stable magnetar scenario of GRBs, an X-ray plateau and a decay phase as $\sim t^{-2}$ should appear in X-ray afterglows. Meanwhile, the ``normal'' X-ray afterglow is produced by the external shock from GRB fireball. We analyze the Neil Gehrels \emph{Swift} GRB data, then find three gold samples, which have an X-ray plateau and a deca…
Short-duration GRBs with extended emission form a subclass of short GRBs, comprising about 15% of the short-duration sample. Afterglow detections of short GRBs are also rare (about 30%) due to their smaller luminosity. We present a multi-band data set of the short burst with extended emission GRB 150424A, comprising of GROND observations, complemented with data from Swift/UVOT, Swift/XRT, HST, Keck/LRIS and data points from the literature. The GRB 150424A afterglow shows an extended plateau phase, lasting about 8hrs. The analysis of this unique GRB afterglow might shed light on the understandi…
We performed calculations of the late radio and X-ray afterglow of GRB/GW170817 in the cocoon-jet paradigm, predicting the appearance of a second peak in the afterglow light curve ~ one-three years after the explosion. The model assumes that the prompt emission and early afterglows originate from a cocoon generated during break-out of the delayed magnetically powered jet. As the jet breaks out from the torus-generated wind, a nearly isotropic mildly relativistic outflow is generated; at the same time the primary jet accelerates to high Lorentz factors and avoids detection. As the fast jet slow…
The X-ray afterglow of GRB 130831A shows an "internal plateau" with a decay slope of $\sim$ 0.8, followed by a steep drop at around $10^5$ s with a slope of $\sim$ 6. After the drop, the X-ray afterglow continues with a much shallower decay. The optical afterglow exhibits two segments of plateaus separated by a luminous optical flare, followed by a normal decay with a slope basically consistent with that of the late-time X-ray afterglow. The decay of the internal X-ray plateau is much steeper than what we expect in the simplest magnetar model. We propose a scenario in which the magnetar underg…
We develop a model of early X-ray afterglows of gamma-ray bursts originating from the reverse shock (RS) propagating through ultra-relativistic, highly magnetized pulsar-like winds produced by long-lasting central engines. We first perform fluid and MHD numerical simulations of relativistic double explosions. We demonstrate that even for constant properties of the wind a variety of temporal behaviors can be produced, depending on the energy of the initial explosion and the wind power, the delay time for the switch-on of the wind, and magnetization of the wind. X-ray emission of the highly magn…
We report our very early optical observations of GRB 110530A and investigate its jet properties together with its X-ray afterglow data. A peculiar broad onset bump followed by a plateau is observed in its early R band afterglow lightcurve. The optical data in the other bands and the X-ray data are well consistent with the temporal feature of the R band lightcurve. Our joint spectral fits of the optical and X-ray data show that they are in the same regime, with a photon index of $\sim 1.70$. The optical and X-ray afterglow lightcurves are well fitted with the standard external shock model by co…
VLBI and Archival VLA and WSRT Observations of the GRB 030329 Radio Afterglow
我们介绍VLBI和档案卡尔G。Jansky甚大阵列（VLA）和Westerbork综合射电望远镜（WSRT）对2003年3月29日伽马射线暴（GRB 030329）的射电余辉的观测，在爆发后672至2032天之间进行。EVLA和WSRT的数据表明，在5 GHz的通量简单的幂律衰减，没有任何明显的迹象，从反喷流的再亮。我们报告了一个未解决的来源，在2032天的大小$1.18\pm0.13$ mas，我们使用结合膨胀率的爆发，认为存在一个统一的，ISM样环爆介质。我们发展了一种半解析的方法来模拟伽马射线暴的余辉，并将其应用到5 GHz的光变曲线进行爆发量热。自行受到$< 0.067$ mas yr $^{-1}$的限制，支持伽马射线暴的标准余辉模型。
Gamma-Ray Bursts (GRBs) are fascinating events due to their panchromatic nature. Their afterglow emission is observed from sub-TeV energies to radio wavelengths. We investigate GRBs that present an optical plateau, leveraging on the resemblance with the X-ray plateau shown in many GRB light curves (LCs). We comprehensively analyze all published GRBs with known redshifts and optical plateau observed mostly by the Neil Gehrels Swift Observatory (Swift). We fit 267 optical LCs and show the existence of the plateau in 102 cases, which is the largest compilation so far of optical plateaus. For 56 S…
Afterglows of Gamma-Ray Bursts (GRBs) are simple in the most basic model, but can show many complex features. The ultra-long duration GRB 111209A, one of the longest GRBs ever detected, also has the best-monitored afterglow in this rare class of GRBs. We want to address the question whether GRB 111209A was a special event beyond its extreme duration alone, and whether it is a classical GRB or another kind of high-energy transient. The afterglow may yield significant clues. We present afterglow photometry obtained in seven bands with the GROND imager as well as in further seven bands with the U…
A plateau phase in the X-ray afterglow is observed in a significant fraction of gamma-ray bursts (GRBs). Previously, it has been found that there exists a correlation among three key parameters concerning the plateau phase, i.e., the end time of the plateau phase in the GRB rest frame ($T_{a}$), the corresponding X-ray luminosity at the end time ($L_{X}$) and the isotropic energy of the prompt GRB ($E_{γ,\rm{iso}}$). In this study, we systematically search through all the \emph{Swift} GRBs with a plateau phase that occurred between 2005 May and 2018 August. We collect 174 GRBs, with redshifts …
X-ray plateaus followed by sharp drops in GRBs 060413, 060522, 060607A and 080330: Further evidences for central engine afterglow from Gamma-ray Bursts
X-ray Analysis of Gamma-Ray Burst Flares and Underlying Afterglows: Insights into Origin of Flares
Bar-Ilan University（巴伊兰大学）；KTH Royal Institute of Technology（皇家理工学院）；The Oskar Klein Centre（奥斯卡·克莱因中心）；Indian Institute of Science Education and Research (IISER)（印度科学教育与研究机构）
Modeling the Multi-Wavelength Afterglow of Short Gamma-Ray Bursts with a Plateau Phase
Nanjing University（南京大学）；Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education（现代天文学与天体物理学教育部重点实验室（南京大学））；Xinjiang Astronomical Observatory, Chinese Academy of Sciences（中国科学院新疆天文台）；Xinjiang Key Laboratory of Radio Astrophysics（新疆射电天文重点实验室）；State Key Laboratory of Radio Astronomy and Technology（射电天文与技术国家重点实验室）；Purple Mountain Observatory, Chinese Academy of Sciences（中国科学院紫金山天文台）；Institute of Space Weather, Nanjing University of Information Science and Technology（南京信息工程大学空间天气研究所）；Guangxi Key Laboratory for Relativistic Astrophysics, School of Physical Science and Technology, Guangxi University（广西大学物理科学与技术学院相对论天体物理学重点实验室）；Institute of Fundamental Physics and Quantum Technology, Ningbo University（宁波大学基础物理与量子技术研究所）
GRB 140903A, a short duration $γ-$ray burst (SGRB) detected by {\it Swift}, is characterized by its long-lasting radio emission among SGRBs. In addition to the $\sim 10^{6}$ s radio afterglow emission, the afterglow of GRB 140903A displays a plateau from $10^3$ s to $7 \times 10^3 $ s in the X-rays. In this work, we attribute the X-ray plateau to the energy injection into the decelerating blast wave and then model the later radio/optical/X-ray afterglow emission within the standard fireball afterglow model. The afterglow emission has been well reproduced with reasonable physical parameters, in…
