A small fraction of GRBs with available data down to soft X-rays ($\sim0.5$ keV) have been shown to feature a spectral break in the low-energy part ($\sim1-10$ keV) of their prompt emission spectrum. The overall spectral shape is consistent with optically thin synchrotron emission from a population of particles that have cooled on a timescale comparable to the dynamic time to energies that are still much higher than their rest mass energy (marginally fast cooling regime). We consider a hadronic scenario and investigate if the prompt emission of these GRBs can originate from relativistic protons that radiate synchrotron in the marginally fast cooling regime. Using semi-analytical methods, we derive the source parameters, such as magnetic field strength and proton luminosity, and calculate the high-energy neutrino emission expected in this scenario. We also investigate how the emission of secondary pairs produced by photopion interactions and $γγ$ pair production affect the broadband photon spectrum. We support our findings with detailed numerical calculations. Strong modification of the photon spectrum below the break energy due to the synchrotron emission of secondary pairs is found, unless the bulk Lorentz factor is very large ($Γ\gtrsim 10^3$). Moreover, this scenario predicts unreasonably high Poynting luminosities because of the strong magnetic fields ($10^6-10^7$ G) that are necessary for the incomplete proton cooling. Our results strongly disfavour marginally fast cooling protons as an explanation of the low-energy spectral break in the prompt GRB spectra.
We compile 23 Gamma-ray Bursts (GRBs) and 21 blazars with estimated Doppler factors, and the Doppler factors of GRBs are estimated from their Lorentz factors by assuming their jet viewing angles θ->0 degree. Using the conventional assumption that the prompt emission of GRBs is dominated by the synchrotron radiation, we calculate the synchrotron luminosity of GRBs from their total isotropic energy and burst duration. Intriguingly, we discover a uniform correlation between the synchrotron luminosity and Doppler factor, L_syn \propto D^3.1, for GRBs and blazars, which suggests that they may share…
We discuss the new surprising observational results that indicate quite convincingly that the prompt emission of Gamma-Ray Bursts (GRBs) is due to synchrotron radiation produced by a particle distribution that has a low energy cut-off. The evidence of this is provided by the low energy part of the spectrum of the prompt emission, that shows the characteristic F(nu) \propto nu^(1/3) shape followed by F(nu) \propto nu^(-1/2) up to the peak frequency. This implies that although the emitting particles are in fast cooling, they do not cool completely. This poses a severe challenge to the basic idea…
We reexamine the general synchrotron model for GRBs' prompt emission and determine the regime in the parameter phase space in which it is viable. We characterize a typical GRB pulse in terms of its peak energy, peak flux and duration and use the latest Fermi observations to constrain the high energy part of the spectrum. We solve for the intrinsic parameters at the emission region and find the possible parameter phase space for synchrotron emission. Our approach is general and it does not depend on a specific energy dissipation mechanism. Reasonable synchrotron solutions are found with energy …
Previous studies have considered synchrotron as the emission mechanism for prompt Gamma-Ray Bursts (GRBs). These works have shown that the electrons must cool on a timescale comparable to the dynamic time at the source in order to satisfy spectral constraints while maintaining high radiative efficiency. We focus on conditions where synchrotron cooling is balanced by a continuous source of heating, and in which these constraints are naturally satisfied. Assuming that a majority of the electrons in the emitting region are contributing to the observed peak, we find that the energy per electron ha…
Bimodal spectral energy distributions (SEDs) of gamma-ray burst (GRB) afterglow of GRBs 190114C, 130427A and 180720B confirm that they are originated from the synchrotron emission (Syn) and synchrotron self-Compton Scattering process (SSC) of electrons accelerated in the jets. The radiation mechanism and the physics of the observed spectrum-luminosity/energy relations of GRBs remain as open questions. By extracting the Syn component through fitting their early afterglow SEDs with the Syn+SSC model, we find that their luminosity ($L_{\rm syn}$), peak energy ($E_{\rm p,syn,z}$), and the Lorentz …
Time-resolved spectroscopy is performed on eight bright, long gamma-ray bursts (GRBs) dominated by single emission pulses that were observed with the {\it Fermi Gamma-ray Space Telescope}. Fitting the prompt radiation of GRBs by empirical spectral forms such as the Band function leads to ambiguous conclusions about the physical model for the prompt radiation. Moreover, the Band function is often inadequate to fit the data. The GRB spectrum is therefore modeled with two emission components consisting of optically thin nonthermal synchrotron radiation from relativistic electrons and, when signif…
We study the effect of Bethe-Heitler (BeHe) pair production on a proton synchrotron model for the prompt emission in gamma-ray bursts (GRBs). The possible parameter space of the model is constrained by consideration of the synchrotron radiation from the secondary BeHe pairs. We find two regimes of interest. 1) At high bulk Lorentz factor, large radius and low luminosity, proton synchrotron emission dominates and produces a spectrum in agreement with observations. For part of this parameter space, a subdominant (in the MeV band) power-law is created by the synchrotron emission of the BeHe pairs…
For decades, gamma-ray bursts (GRBs) have been broadly divided into `long'- and `short'-duration bursts, lasting more or less than 2s, respectively. However, this dichotomy does not map perfectly to the two progenitor channels that are known to produce GRBs -- the merger of compact objects (merger-GRBs) or the collapse of massive stars (collapsar-GRBs). In particular, the merger-GRBs population may also include bursts with a short, hard $\lesssim$2s spike and subsequent longer, softer extended emission (EE). The recent discovery of a kilonova -- the radioactive glow of heavy elements made in n…
The dominant component of the (100 MeV - 50 GeV) GRB emission detected by LAT starts with a delay relative to the prompt soft (sub-MeV) gamma-rays and lasts long after the soft component fades. This has lead to the intriguing suggestion that this high energy emission is generated via synchrotron emission of relativistic electrons accelerated by the external shock. Moreover, the limits on the MeV afterglow emission lead to the suggestion that, at least in bright GeV bursts the field is not amplified beyond compression in the shock. We show here that considerations of confinement (within the dec…
We discuss the synchrotron emission of fast cooling electrons in shocks. The fast cooling electrons behind the shocks can generate a position-dependent inhomogeneous electron distribution if they do not have enough time to mix homogeneously. This would lead to a very different synchrotron spectrum in low-frequency bands to that in the homogeneous case due to the synchrotron absorption. In this paper, we calculate the synchrotron spectrum in the inhomogeneous case in a gamma-ray burst (GRB). Both the forward shock and the reverse shock are considered. We find for the reverse shock dominated cas…
After more than 40 years from their discovery, the long-lasting tension between predictions and observations of GRBs prompt emission spectra starts to be solved. We found that the observed spectra can be produced by the synchrotron process, if the emitting particles do not completely cool. Evidence for incomplete cooling was recently found in Swift GRBs spectra with prompt observations down to 0.5 keV (Oganesyan et al. 2017, 2018), characterized by an additional low-energy break. In order to search for this break at higher energies, we analysed the 10 long and 10 short brightest GRBs detected …
We calculate the high energy afterglow emission from short Gamma-Ray Bursts (SGRBs) in the external shock model. There are two possible components contributing to the high energy afterglow: the electron synchrotron emission and the synchrotron self-Compton (SSC) emission. We find that for typical parameter values of SGRBs, the early high-energy afterglow emission in 10 MeV-10 GeV is dominated by the synchrotron emission. For a burst occurring at redshift z =0.1, the high-energy emission can be detectable by Fermi LAT if the blast wave has an energy E>=10^51 ergs and the fraction of energy in e…
It has been suggested that the prompt emission in gamma-ray bursts consists of several components giving rise to the observed spectral shape. Here we examine a sample of the 8 brightest, single pulsed {\it Fermi} bursts whose spectra are modelled by using synchrotron emission as one of the components. Five of these bursts require an additional photospheric component (blackbody). In particular, we investigate the inferred properties of the jet and the physical requirements set by the observed components for these five bursts, in the context of a baryonic dominated outflow, motivated by the stro…
We analyzed 199 GRBs detected by Fermi-LAT during the years 2008-2019. We found 67 photons at energies >=10 GeV, which come from 34 GRBs. Out of these 34 GRBs, Fermi-LAT detects significant (TS>=4) afterglow 0.1-200 GeV photons from 25 GRBs. We present time-integrated 0.1-200 GeV spectra of these 25 GRBs. The spectra of a significant fraction (9/25) of these GRBs revealed a harder component above an energy break of 0.3-2 GeV. While shock synchrotron may account for the photons at the lower energy end, high energy photons above the break is naturally explained by synchrotron self-Compton (SSC) …
Synchrotron radiation from a decelerating blastwave is a widely accepted model of radio to X-ray afterglow emission from gamma-ray bursts (GRBs). GeV gamma-ray emission detected by the Fermi Large Area Telescope (LAT) and the duration of which extends beyond the prompt gamma-ray emission phase, is also compatible with broad features of afterglow emission. We revisit the synchrotron self-Compton (SSC) emission model from a decelerating blastwave to fit multiwavelength data from three bright GRBs, namely GRB~190114C, GRB~130427A and GRB~090510. We constrain the afterglow model parameters using t…
Synchrotron emission polarization is very sensitive to the magnetic field configuration. Recently, polarization of synchrotron emission with a mixed (SM) magnetic field in Gamma-ray burst (GRB) afterglow phase had been developed. Here, we apply these SM models to GRB prompt phase and compare their polarization properties with that of synchrotron emission in purely ordered (SO) magnetic field. We find that the polarization properties in a SM model are very similar to these in a corresponding SO model (e.g., synchrotron emission in a mixed magnetic field with an aligned ordered part (SMA) and sy…
Synchrotron polarization of anisotropic electron distribution in GRB prompt emission
Guangxi University（广西大学）；Guangxi Minzu University（广西民族大学）；Yunnan Observatories, Chinese Academy of Sciences（中国科学院云南天文台）；Center for Astronomical Mega-Science, Chinese Academy of Science（中国科学院国家天文台）
We constrain the distance of the Gamma-Ray Burst (GRB) prompt emission site from the explosion centre, R, by determining the location of the electron's self absorption frequency in the GRB prompt optical-to-X/gamma-ray spectral energy distribution, assuming that the optical and the gamma-ray emissions are among the same synchrotron radiation continuum of a group of hot electrons. All possible spectral regimes are considered in our analysis. The method has only two assumed parameters, namely, the bulk Lorentz factor of the emitting source Gamma, and the magnetic field strength B in the emission…
Gamma-ray bursts (GRBs) are intense bursts of high-energy photons (prompt emissions) caused by relativistic jets. After the emissions, multi-wavelength afterglows, from radio to very-high-energy (VHE) gamma-ray, last for more than a few days. In the past three years, the VHE gamma-ray photons from four GRBs (GRBs 180720B, 190114C, 190829A and 201216C) were detected by ground-based Imaging Atmospheric Cherenkov Telescopes, such as the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescopes and the High Energy Stereoscopic System (H.E.S.S.). One of them, GRB 190829A, had some peculiar featu…
We present a spectral analysis for a sample of redshift known GRBs observed with {\em Fermi}/GBM. Together with the results derived from our systematical spectral energy distribution modeling with the leptonic models for a {\em Fermi}/LAT blazar sample, we compare the distributions of the GRBs and the blazars by plotting the synchrotron peak luminosity ($L_{\rm s}$) and the corresponding peak photon energy $E_{\rm s}$ of blazars in the $L_{\rm p}-E_{\rm p}$ plane of GRBs, where $L_{\rm p}$ and $E_{\rm p}$ are the peak luminosity and peak photon energy of the GRB time-integrated $νf_ν$ spectrum…
The emission processes active in the highly relativistic jets of gamma-ray bursts (GRBs) remain unknown. In this paper we propose a new measure to describe spectra: the width of the $EF_E$ spectrum, a quantity dependent only on finding a good fit to the data. We apply this to the full sample of GRBs observed by Fermi/GBM and CGRO/BATSE. The results from the two instruments are fully consistent. We find that the median widths of spectra from long and short GRBs are significantly different (chance probability $<10^{-6}$). The width does not correlate with either duration or hardness, and this is…
The long standing problem of identifying the emission mechanism operating in gamma-ray bursts (GRBs) has produced a myriad of possible models that have the potential of explaining the observations. Generally, the empirical Band function is fit to the observed gamma-ray data and the fit parameters are used to infer which radiative mechanisms are at work in GRB outflows. In particular, the distribution of the Band function's low-energy power law index, $α$, has led to the so-called synchrotron "line-of-death" (LOD) which is a statement that the distribution cannot be explained by the simplest of…
We study time-resolved spectra of the prompt emission of Swift Gamma-ray bursts (GRB). Our goal is to see if previous BATSE claims of the existence of a large amount of spectra with the low energy photon indices harder than 2/3 are consistent with Swift data. We perform a systematic search of the episodes of the spectral hardening down to the photon indices below 2/3 in the prompt emission spectra of Swift GRBs. We show that the data of the BAT instrument on board of Swift are consistent with BATSE data, if one takes into account differences between the two instruments. Much lower statistics o…
The unexpected nearby gamma-ray burst GRB 170817A associated with the LIGO binary neutron star merger event GW170817 presents a challenge to the current understanding of the emission physics of short gamma-ray bursts (GRBs). The event's low luminosity but similar peak energy compared to standard short GRBs are difficult to explain with current models, challenging our understanding of the GRB emission process. Emission models invoking synchrotron radiation from electrons accelerated in shocks and photospheric emission are particularly challenging explanations for this burst.
We analyze the >100MeV data for 3 GRBs detected by Fermi (GRBs 080916C, 090510, 090902B) and find that these photons were generated via synchrotron emission in the external forward shock. We arrive at this conclusion by four different methods as follows. (1) We check the light curve and spectral behavior of the >100MeV data, and late time X-ray and optical data, and find them consistent with the closure relations for the external forward shock radiation. (2) We calculate the expected external forward shock synchrotron flux at 100MeV, and it matches the observed flux value. (3) We determine the…
Detection of afterglow emission up to 100 GeV through a stacking analysis of gamma-ray bursts
Yunnan University（云南大学）；Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所）；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）；University of Chinese Academy of Sciences（中国科学院大学）；TIANFU Cosmic Ray Research Center（天府宇宙线研究中心）；Beijing Normal University（北京师范大学）；The Hong Kong Institute for Astronomy and Astrophysics, University of Hong Kong（香港大学天体物理研究所）；Department of Physics, University of Hong Kong（香港大学物理系）
We present analytic approximations to the optically thin synchrotron and synchrotron self-Compton (SSC) spectra when Klein-Nishina (KN) effects are important and pair production and external radiation fields can be neglected. This theory is useful for analytical treatment of radiation from astrophysical sources, such as gamma-ray bursts (GRBs), active galactic nuclei and pulsar wind nebula, where KN effects may be important. We consider a source with a continuous injection of relativistic electrons with a power-law energy distribution above some typical injection energy. We find that the synch…
Many different physical processes have been suggested to explain the prompt gamma-ray emission in gamma-ray bursts (GRBs). Although there are examples of both bursts with photospheric and synchrotron emission origins, these distinct spectral appearances have not been generalized to large samples of GRBs. Here, we search for signatures of the different emission mechanisms in the full Fermi Gamma-ray Space Telescope GBM catalogue. We use Gaussian Mixture Models to cluster bursts according to their parameters from the Band function ($α$, $β$, and $E_{pk}$) as well as their fluence and $T_{90}$. W…
Recently, very high-energy photons above 100 GeV were reported to be detected from GRB~190114C and GRB~180720B at, respectively, 100-1000 s and 10 hours after the burst. We model the available broad-band data of both GRBs with the synchrotron plus synchrotron self-Compton (SSC) emission of the afterglow shocks. We find that the sub-TeV emission of GRB~180720B can be interpreted as the SSC emission from afterglow shocks expanding in a constant density circum-burst medium. The SSC emission of GRB~190114C dominates over the synchrotron component from GeV energies at $\sim100$ s, which can explain…
Recent particle-in-cell simulations suggest that a large fraction of the energy dissipated in a relativistic shock is deposited into a Maxwellian distribution of electrons that is connected to the high-energy power-law tail. Here, we explore the observational implications of such a mixed thermal-nonthermal particle distribution for the afterglow and prompt emission of gamma-ray bursts. When the Maxwellian component dominates the energy budget, the afterglow lightcurves show a very steep decline phase followed by a more shallow decay when the characteristic synchrotron frequency crosses the obs…
Relativistic electrons accelerated by both the first-order and the second-order Fermi accelerations in some synchrotron sources have a hybrid shape of thermal and nonthermal energy distribution. This particle acceleration result is supported by some recent numerical simulations. We calculate the synchrotron polarization by applying this electron energy distribution. The polarization degrees in the cases of active galactic nucleus (AGN) jets and gamma-ray bursts (GRBs) are given as examples. The possible application for the polarization study of Sgr A* is also mentioned. We finally suggest high…
{\it Fermi} satellite has detected extra spectral components in GeV energy range in several GRBs. Those components have power-law shapes, which may contribute to also X-ray band. The limited photon statistics make it difficult to determine the origin of GeV photons, namely internal or external shocks. We try to explain the extra components with our numerical simulations based on internal dissipation picture. Our leptonic model may reproduce not only the GeV excess via SSC emission but also the low-energy excess via the late synchrotron emission from remnant electrons. The hadronic models also …
The long-lasting tension between the observed spectra of gamma ray bursts (GRBs) and the predicted synchrotron emission spectrum might be solved if electrons do not completely cool. Evidence for incomplete cooling was recently found in Swift GRBs with prompt observations down to 0.1 keV and in one bright Fermi burst, GRB 160625B. Here we systematically search for evidence of incomplete cooling in the spectra of the ten brightest short and long GRBs observed by Fermi. We find that in 8/10 long GRBs there is compelling evidence of a low energy break (below the peak energy) and good agreement wit…
Gamma-ray bursts (GRBs) are fascinating extragalactic objects. They represent a fantastic opportunity to investigate unique properties not exhibited in other sources. Multi-wavelength afterglow observations from some short- and long-duration GRBs reveal an atypical long-lasting emission that evolves differently from the canonical afterglow light curves favoring the off-axis emission. We present an analytical synchrotron afterglow scenario, and the hydrodynamical evolution of an off-axis top-hat jet decelerated in a stratified surrounding environment. The analytical synchrotron afterglow model …
Gamma-ray bursts are the most energetic electromagnetic sources in the Universe. Their prompt gamma-ray radiation corresponds to an energy release of 1E42-1E47J. Fifty years after their discovery and several dedicated space-based instruments, the physical origin of this emission is still unknown. Synchrotron emission has been one of the early contenders but was criticized because spectral fits of empirical models (such as a smoothly-connected broken power law or a cut-off power law) suggest too hard a slope of the low-energy power law, violating the so-called synchrotron line-of-death. We perf…
In the internal shock model for gamma-ray bursts (GRBs), the synchrotron spectrum from the fast cooling electrons in a homogeneous downstream magnetic field (MF) is too soft to produce the low-energy slope of GRB spectra. However the magnetic field may decay downstream with distance from the shock front. Here we show that the synchrotron spectrum becomes harder if electrons undergo synchrotron and inverse-Compton cooling in a decaying MF. To reconcile this with the typical GRB spectrum with low energy slope $νF_ν\proptoν$, it is required that the postshock MF decay time is comparable to the co…
As we further our studies on Gamma-ray bursts (GRBs), both on theoretical models and observational tools, more and more options begin to open for exploration of its physical properties. As transient events primarily dominated by synchrotron radiation, it is expected that the synchrotron photons emitted by GRBs should present some degree of polarization throughout the evolution of the burst. Whereas observing this polarization can still be challenging due to the constraints on observational tools, especially for short GRBs, it is paramount that the groundwork is laid for the day we have abundan…
Aims. With the accumulation of polarization data in the gamma-ray burst (GRB) prompt phase, polarization models can be tested. Methods. We predicted the time-integrated polarizations of 37 GRBs with polarization observation. We used their observed spectral parameters to do this. In the model, the emission mechanism is synchrotron radiation, and the magnetic field configuration in the emission region was assumed to be large-scale ordered. Therefore, the predicted polarization degrees (PDs) are upper limits. Results. For most GRBs detected by the Gamma-ray Burst Polarimeter (GAP), POLAR, and Ast…
When an emitting spherical shell with a constant Lorentz factor turns off emission abruptly at some radius, its high-latitude emission would obey the relation of $\hatα$ (the temporal index) = $2 + \hatβ$ (the spectral index). However, this relation is violated by the X-ray fares in some gamma-ray bursts (GRBs), whose $\hatα$ is much more steeper. We show that the synchrotron radiation should be anisotropic when the angular distribution of accelerated electrons has preferable orientation, and this anisotropy would naturally lead to the steeper decay for the high-latitude emission if the the in…
Relativistic jets launched by rotating black holes are powerful emitters of non-thermal radiation. Extraction of the rotational energy via electromagnetic stresses produces magnetically-dominated jets, which may become turbulent. Studies of magnetically-dominated plasma turbulence from first principles show that most of the accelerated particles have small pitch angles, i.e. the particle velocity is nearly aligned with the local magnetic field. We examine synchrotron-self-Compton radiation from anisotropic particles in the fast cooling regime. The small pitch angles reduce the synchrotron cool…
Polarization can serve as a probe of the radiation mechanism and magnetic field (MF) configuration in gamma-ray bursts (GRBs). In the case of constant MF, the synchrotron polarization in the prompt phase of GRBs has been widely studied. In this paper, we consider the case of the decaying MF. We calculate the time-averaged and instantaneous synchrotron polarizations in a pulse for different viewing angles and for the large-scale decaying MF model, which can explain the so-called Band spectrum. We find that the on-axis time-averaged polarization degree (PD) in the energy band of 50-500 keV for t…
We analyze gamma-ray bursts (GRBs) detected by \textit{Fermi}/Gamma-Ray Burst Monitor (GBM) and having single pulse. We fit the light curves with a model having exponential rise and decay parts. We perform a detailed time-resolved spectroscopy using four models: Band, blackbody with a power-law (BBPL), multicolour blackbody with a power-law (mBBPL) and two blackbodies with a power-law (2BBPL). We find that models other than the BBPL give better $χ_{red}^2$ for the "hard-to-soft" (HTS) pulses, while for the "intensity tracking" (IT) pulses, the BBPL model is statistically as good as the other m…
Time-resolved spectro-polarimetric analysis of extremely bright GRB 230307A: Possible Evidence of evolution from photospheric to synchrotron dominated emission
GRB 230307A的光谱偏振分析揭示了从光球主导到同步辐射主导的转变，可能表明磁场在喷流动力学中的演变作用。
Inhomogeneities can influence the polarisation emerging from a synchrotron source. However, it is shown that the frequency distribution of circular polarisation is only marginally affected, although its magnitude may change substantially. This is used to argue that the observed properties of compact radio sources imply a radiating plasma in which the characteristic waves are nearly circular. As a result, restrictions can be put on the low energy part of the energy distribution of the relativistic electrons as well as the presence of electron-positron pairs. It is emphasised that this constrain…
Fermi gamma-ray telescope data of GRB 080916C with ~1e55 erg in apparent isotropic gamma-ray energy, show a several second delay between the rise of 100 MeV - GeV radiation compared with keV - MeV radiation. Here we show that synchrotron radiation from cosmic ray protons accelerated in GRBs, delayed by the proton synchrotron cooling timescale in a jet of magnetically-dominated shocked plasma moving at highly relativistic speeds with bulk Lorentz factor Gamma ~ 500, could explain this result. A second generation electron synchrotron component from attenuated proton synchrotron radiation makes e…
Although the physical origin of prompt emission in gamma-ray bursts (GRBs) remains inconclusive, previous studies have considered the synchrotron radiation of relativistic electrons as a promising mechanism. These works usually adopted a invariable injection rate of electrons ($Q$) which may be discordant with that in a Poynting-flux dominated jet. In a Poynting-flux dominated jet (e.g., ICMART model, Zhang & Yan 2011), the number of magnetic reconnections occurred simultaneously may grow rapidly with time and results in an increase of $Q$ with time. This paper is dedicated to study the synchr…
Shear Particle Acceleration in Structured Gamma-Ray Burst Jets: I. Physical Origin of the Band Function and Application to GRBs 090926A, 131108A, and 160509A
This paper examines the possibility that hadronic processes produce the >100 MeV photons in the prompt phase of gamma-ray bursts (GRBs) observed by the Fermi-LAT. We calculate analytically the radiation from protons and from secondary electron-positron pairs produced by high energy protons interacting with gamma-rays inside of the GRB jet. We consider both photo-pion and Bethe-Heitler pair production processes to create secondary electrons and positrons that then radiate via inverse Compton and synchrotron processes. We also consider synchrotron radiation from the protons themselves. We calcul…
Active galactic nuclei (AGNs) and gamma-ray bursts (GRBs) are powerful astrophysical events with relativistic jets. In this Letter the broadband spectral properties are compared between GRBs and the well-observed blazars. The distribution of GRBs are consistent with the well-known blazar sequence including the $νL_ν(5\rm GHz)-α_{\rm RX}$ and $νL_ν(5\rm GHz)-ν_{\rm peak}$ correlations, where $α_{\rm RX}$ is defined as the broadband spectral slope in radio-to-X-ray bands, and $ν_{\rm peak}$ is defined as the spectral peak frequency. Moreover, GRBs occupy the low radio luminosity end of these seq…
