Conveners
Gamma-Ray Burst Correlations: Observational Challenges and Theoretical Interpretation: Block 1
- Liang Li (ICRANet, Piazza della Repubblica 10, I-65122 Pescara, Italy)
- Maria Dainotti (National Astronomical Observatory of Japan)
Gamma-Ray Burst Correlations: Observational Challenges and Theoretical Interpretation: Block 2
- Maria Dainotti (National Astronomical Observatory of Japan)
- Liang Li (ICRANet, Piazza della Repubblica 10, I-65122 Pescara, Italy)
Gamma-Ray Burst Correlations: Observational Challenges and Theoretical Interpretation: Block 3
- Liang Li (ICRANet, Piazza della Repubblica 10, I-65122 Pescara, Italy)
- Maria Dainotti (National Astronomical Observatory of Japan)
Description
Gamma-Ray Bursts are among the most distant phenomena in the Universe and because of that they can be used as standardizable candles through important correlations. The session will discuss the role of correlations both in prompt and afterglow, from high-energy gamma-rays to optical and radio observations. It will also deal with all the challenges in observations and the possible theoretical interpretation. The session will discuss also the application of them as cosmological tools and how satellites like Swift, Beppo-Sax and future mission can advantage of these correlations at high-z.
A large fraction of Gamma-Ray Bursts (GRBs) lightcurves (LCs) shows X-ray plateaus. We analyze all GRBs with known redshifts presenting plateaus observed by The Neil Gehrels Swift Observatory from its launch until August 2019. The fundamental plane relation between the rest-frame time and X-ray luminosity at the end of the plateau emission and the peak prompt luminosity holds for all the GRB...
Neutron-star mergers and their remnants are fascinating both as laboratories for physics at high energies and densities and because of their likely importance for the production of heavy elements. There are several approaches to observing these mergers. First, we can locate the EM counterparts of neutron-star GW events. This was spectacularly successful with GW170817, but despite huge efforts...
We perform optial follow-up observations of transients such as gravitational
wave signals and fast radio bursts with the Subaru telescope/Hyper Suprime-Cam (HSC),
which is a wide field camera with a field of view of 1.7deg2. The Subaru/HSC
has the highest light collecting power in unit time among all optical telescopes
currently in operation. In this presentation, I will introduce our...
Relativistic protons, at the forward external shock of a GRB relativistic blast wave (RBW) become unstable to converting their energy dynamically into e+e- pairs through the emission of synchrotron radiation by these e+e-pairs when their column density becomes higher than a critical value given by $n R \sigma \Gamma^4 \simeq 2$ ($n$ is the ambient density, $R$ the shock radius, $\Gamma$ the...
A large fraction of gamma-ray burst (GRB) light curves (LCs) exhibit plateaus in their afterglow. Since GRBs phenomena are panchromatic in nature, emitting wavelengths from X-ray to radio, there is opportunity to study GRBs along multiple electromagnetic regimes. In this work, we further investigate more than 130 GRBs that show optical plateaus in their LCs. We confirm the two-dimensional...
Gamma-Ray Burst (GRB) afterglow emission can be observed from sub-TeV energies to radio wavelengths, though radio afterglows are less common. We examine GRB radio light curves to look for the presence of radio plateaus, resembling the plateaus observed in X-ray and optical light curves. We analyze all published GRBs with observed radio afterglow and fit 64 radio light curves with the broken...
Cosmological models and the values of their related parameters are widely debated, due to tension in the results obtained by Planck measurements of the Cosmic Microwave Background (CMB) Radiation in the early universe, and Supernovae Type Ia (SNe Ia) data within the late universe. Therefore, we must also consider high-redshift cosmological probes to properly reconstruct a chronological cosmos...
A large fraction of gamma-ray Bursts (GRBs) lightcurves (LCs) show X-ray plateaus. We analyze all GRBs with known redshifts presenting plateaus observed by The Neil Gehrels Swift Observatory from its launch until 2019 August. The fundamental plane relation between the rest-frame time and X-ray luminosity at the end of the plateau emission and the peak prompt luminosity holds for all the GRB...
I will review several GRB correlations reported in the literature and discuss possible physical mechanisms behind them. Topics to be covered include Amati/Yonetoku relations, Frail relation, Ghirlanda/Liang-Zhang relations, energy/luminosity-Lorentz factor (Liang-Lü relation), Dainotti relation, and several three-parameter fundamental-plane relations. These correlations provide hints on the...
The correlation between the photon energy at which the nuFnu spectrum in the cosmological rest-frame peaks, Ep,i, and the isotropic-equivalent radiated energy, Eiso, is one of the most investigated observaitonal properties of Gamma-Ray Bursts (GRB). In addition to its relevance for understanding the physics of prompt emission, identifying sub-classes of GRBs, shedding light on jet structure...
The central engine of gamma-ray bursts may be neutron stars. However, the internal structure of neutron stars is still largely uncertain. It has been suggested that strange-quark matter (SQM) may be the true ground state of hadronic matter, indicating that the observed pulsars may actually be strange stars (SSs), but not neutron stars. According to the SQM hypothesis, the existence of a...
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 hr after the burst. We model the available broadband 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 GRB180720B can be interpreted as the SSC emission...
Since its discovery in 2005, the plateau phase seen in the early x-ray afterglow of a significant fraction (10's of %) of GRBs confuse theoreticians. A close look reveals that "plateau" bursts nearly never show evidence for LAT emission, neither a thermal component. Using this a hint, I argue that the plateau is due to the coasting of GRB jets in a "wind"-like medius. I will provide the...
The origin of the plateau phase seen in the early X-ray light curves of GRBs (up to thousands of seconds) is a debated topic. I will present a new model formulation as explanation of the plateau emission and its application to the observation in both X-ray and optical bands. Main outcomes of this application is that (i) the end of the plateau phase marks the transition from the coasting phase...
For gamma-ray bursts (GRBs) with a plateau phase in the X-ray afterglow, a so-called L-T-E correlation has been found which tightly connects the isotropic energy of the prompt GRB (Eγ,iso) with the end time of the X-ray plateau (Ta) and the corresponding X-ray luminosity at the end time (LX ). Here we show that there is a clear redshift evolution in the correlation. Furthermore, since the...
We propose a Backscattering dominated prompt emission model for gamma ray bursts' (GRB) prompt phase in which the photons generated through pair annihilation at the centre of a GRB are backscattered through Compton scattering by an outflowing stellar cork. Using pair annihilation spectrum for seed photons, we show that the obtained spectra are capable of explaining the low energy and the high...
Gamma-ray bursts (GRBs) correspond to the most energetic electromagnetic events known. These events can release a large amount of energy during a time scale ranging from a few milliseconds to tens of seconds. Based on their duration, we can classify them into short and long events, being the production process in each case different. In this work, we study this sort of astrophysical source...
Combining information from the first gravitational wave detected gamma-ray burst, GRB 170817 with observations of cosmological GRBs holds important lessons for understanding the structure of GRB jets and the required conditions at the emitting region. It also re-frames our understanding of more commonly observed phenomena in GRBs, such as X-ray plateaus, and sets our expectations for future...
Short GRBs are unique tools that allow us to study binary neutron star (NS) mergers across all cosmic times. The study of short GRBs at high redshifts is particularly important as it allows us to estimate the typical lifetime of their progenitors, and whether they merged early enough to enrich the universe with heavy elements. In this contribution I will review the high-energy properties of...
Many short Gamma-Ray Bursts (sGRBs) have a prolonged plateau in the X-ray afterglow lasting up to tens of thousands of seconds. A central engine injecting energy into the remnant may fuel the plateau. We develop a simple analytic model which naturally produces X-ray plateaux using a magnetar as the central engine. Our model leverages well-established descriptions of young supernova remnants...
Newly-born millisecond magnetars are competing with black holes as source of the gamma-ray burst (GRB) power. In ten years of activity, Swift has provided compelling but indirect evidences supporting the magnetar central engine for both long and short GRBs, that is currently the best way to interpret several correlations observed between prompt and afterglow properties. We review the main...
After 15 years of Swift observations, the knowledge of the class of short GRBs experienced an impressive boost. The discovery of short GRB afterglows in 2005, provided the first insight into their energy scale, environments and host galaxies. The lack of detection of associated supernovae proved that their progenitors are not massive stars. The spectacular detection of the first...
I will discuss supernovae associated with gamma-ray bursts and what they tell us about the progenitors of gamma-ray bursts. I will focus on the supernova diversity from gamma-ray bursts and what the diversity tells us.
In the current study, we present hydrodynamical simulations and post-process radiation transfer calculations of photospheric emission in GRBs. Our simulations show that the photospheric emission can reproduce the observed correlations among the spectral peak energy, $E_p$, peak luminosity, $L_p$, and isotropic energy, $E_{iso}$, as a consequence of the viewing angle dependence. We also find...
The broadband afterglows of gamma-ray bursts provide a wealth of information vital for interpreting these extremely energetic events: the progenitor systems, the hydrodynamics of the GRB, the microphysics of relativistic shocks, and more. A proper understanding of afterglows may even allow GRBs to extend the cosmic distance ladder. However, our interpretation of afterglows is shaped by the...
We present a correlation observed in both the optical and X-ray afterglows of long duration Gamma-ray Bursts (GRBs), between the initial luminosity (measured at restframe 200s) and average afterglow decay rate. This correlation does not depend on the presence of specific light curve features and is potentially applicable to all long GRB afterglows. We explore how the correlation decay...
The Fermi-LAT collaboration presented the second gamma-ray burst (GRB) catalog covering its first ten years of operations. A large fraction of light curves (LCs) in this catalog cannot be explained by the closure relations of the standard synchrotron forward-shock (FS) model, suggesting that there could be an essential contribution from another process. Therefore, we derive the synchrotron...
