Gamma-Ray Bursts Afterglow Physics and the VHE Domain

Miceli, Davide; Nava, Lara

doi:10.3390/galaxies10030066

Cited by 25 publications

(14 citation statements)

References 186 publications

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“…Furthermore, observations of prompt and afterglow emission from both long and short GRBs provide unique insights into the physics of energy transport and dissipation within relativistic jets (see e.g., Kumar & Zhang 2015; Miceli & Nava 2022 for review articles). For example, the very recent opening of the so-called VHE (Very High Energy) window, with the detection of TeV emission from GRB afterglows (MAGIC Collaboration et al 2019; Abdalla et al 2019; H.E.S.S.…”

Section: Introductionmentioning

confidence: 99%

Localisation of gamma-ray bursts from the combined SpIRIT+HERMES-TP/SP nano-satellite constellation

Thomas

Trenti²,

Sanna³

et al. 2023

Publ. Astron. Soc. Aust.

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Multi-messenger observations of the transient sky to detect cosmic explosions and counterparts of gravitational wave mergers critically rely on orbiting wide-FoV telescopes to cover the wide range of wavelengths where atmospheric absorption and emission limit the use of ground facilities. Thanks to continuing technological improvements, miniaturised space instruments operating as distributed-aperture constellations are offering new capabilities for the study of high-energy transients to complement ageing existing satellites. In this paper we characterise the performance of the upcoming joint SpIRIT and HERMES-TP/SP constellation for the localisation of high-energy transients through triangulation of signal arrival times. SpIRIT is an Australian technology and science demonstrator satellite designed to operate in a low-Earth Sun-synchronous Polar orbit that will augment the science operations for the equatorial HERMES-TP/SP constellation. In this work we simulate the improvement to the localisation capabilities of the HERMES-TP/SP constellation when SpIRIT is included in an orbital plane nearly perpendicular (inclination = 97.6• ) to the HERMES-TP/SP orbits. For the fraction of GRBs detected by three of the HERMES satellites plus SpIRIT, we find that the combined constellation is capable of localising 60% of long GRBs to within ∼30 deg 2 on the sky, and 60% of short GRBs within ∼1850 deg 2 (1σ confidence regions), though it is beyond the scope of this work to characterise or rule out systematic uncertainty of the same order of magnitude. Based purely on statistical GRB localisation capabilities (i.e., excluding systematic uncertainties and sky coverage), these figures for long GRBs are comparable to those reported by the Fermi Gamma Burst Monitor instrument. These localisation statistics represents a reduction of the uncertainty for the burst localisation region for both long and short GRBs by a factor of ∼5 compared to the HERMES-TP/SP alone. Further improvements by an additional factor of 2 (or 4) can be achieved by launching an additional 4 (or 6) SpIRIT-like satellites into a Polar orbit, respectively, which would both increase the fraction of sky covered by multiple satellite elements, and also enable localisation of ≥60% of long GRBs to within a radius of ∼1.5 • (statistical uncertainty) on the sky, clearly demonstrating the value of a distributed all-sky high-energy transient monitor composed of nano-satellites.

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Section: Introductionmentioning

confidence: 99%

Localisation of gamma-ray bursts from the combined SpIRIT+HERMES-TP/SP nano-satellite constellation

Thomas

Trenti²,

Sanna³

et al. 2023

Publ. Astron. Soc. Aust.

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“…This process is a natural by-product of the classical synchrotronemission model, and can account for emission in this energy band. However, it is not clear yet whether this model can explain the broadband data (at all wavelengths), given the strong constraints on the TeV band flux from radio, optical, and X-ray data (González et al 2023;Miceli & Nava 2022). Furthermore, this model cannot explain the 10 TeV energy photons (Huang et al 2022) originally claimed to be observed (González et al 2023;Ren et al 2023;Laskar et al 2023a;Das & Razzaque 2023;Kann et al 2023).…”

Section: Introductionmentioning

confidence: 99%

“…The prompt phase is then followed by an extended broadband afterglow, detected at all energy bands, from radio to a few hundreds of GeVs and possibly even higher (for reviews, see, e.g., Piran 1999;Mészáros 2006;Kumar & Zhang 2015;Zhang 2018). Detections of GRB afterglows at the highest energies (i.e., >300 GeV) have been on the rise in the past two decades (for reviews, see, e.g., Nava 2018;Miceli & Nava 2022). Understanding the physics underlying this emission has become of highest importance as it holds clues to better constrain and understand the afterglow of GRBs.…”

Section: Introductionmentioning

confidence: 99%

Hybrid Emission Modeling of GRB 221009A: Shedding Light on TeV Emission Origins in Long GRBs

Isravel,

Bégué,

Pe’er

2023

ApJ

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Observations of long-duration gamma-ray bursts (GRBs) with TeV emission during their afterglow have been on the rise. Recently, GRB 221009A, the most energetic GRB ever observed, was detected by the Large High Altitude Air Shower Observatory experiment in the energy band 0.2–7 TeV. Here, we interpret its afterglow in the context of a hybrid model in which the TeV spectral component is explained by the proton-synchrotron process while the low-energy emission from optical to X-ray is due to synchrotron radiation from electrons. We constrained the model parameters using the observed optical, X-ray, and TeV data. By comparing the parameters of this burst and of GRB 190114C, we deduce that the VHE emission at energies ≥1 TeV in the GRB afterglow requires large explosion kinetic energy, E ≳ 1054 erg and a reasonable circumburst density, n ≳ 10 cm−3. This results in a small injection fraction of particles accelerated to a power law, ∼10−2. A significant fraction of shock energy must be allocated to a near equipartition magnetic field, ϵ B ∼ 10−1, while electrons should only carry a small fraction of this energy, ϵ e ∼ 10−3. Under these conditions required for a proton-synchrotron model, namely ϵ B ≫ ϵ e , the SSC component is substantially subdominant over proton-synchrotron as a source of TeV photons. These results lead us to suggest that proton-synchrotron process is a strong contender for the radiative mechanisms explaining GRB afterglows in the TeV band.

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“…Gamma-ray bursts (GRBs) are among the most luminous explosions in the universe (Mészáros 2006;Kumar & Zhang 2014). In 2019, the detection of two TeV bursts, GRB 190114C (MAGIC Collaboration et al 2019;MAGIC Collaboration 2019) and GRB 180720B (Abdalla et al 2019), opened a new window in the very high-energy (VHE)(0.1 TeV) band for studying GRBs, providing us with new opportunities to investigate the nature of GRBs (see Gill &Granot 2022 andMiceli &Nava 2022 for reviews).…”

Section: Introductionmentioning

confidence: 99%

External Inverse-compton and Proton Synchrotron Emission from the Reverse Shock as the Origin of VHE Gamma Rays from the Hyper-bright GRB 221009A

Zhang

Murase

Ioka

et al. 2023

ApJL

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The detection of the hyper-bright gamma-ray burst (GRB) 221009A enables us to explore the nature of the GRB emission and the origin of very high-energy gamma rays. We analyze the Fermi Large Area Telescope (Fermi-LAT) data of this burst and investigate the GeV–TeV emission in the framework of the external reverse-shock model. We show that the early ∼1–10 GeV emission can be explained by the external inverse-Compton mechanism via upscattering MeV gamma rays by electrons accelerated at the reverse shock, in addition to the synchrotron self-Compton component. The predicted early optical flux could have been brighter than that of the naked-eye GRB 080319B. We also show that proton synchrotron emission from accelerated ultrahigh-energy cosmic rays (UHECRs) is detectable and could potentially explain ≳TeV photons detected by LHAASO or constrain the UHECR acceleration mechanism. Our model suggests that the detection of  ( 10 TeV ) photons with energies up to ∼18 TeV is possible for reasonable models of the extragalactic background light without invoking new physics and predicts anticorrelations between MeV photons and TeV photons, which can be tested with the LHAASO data.

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Gamma-Ray Bursts Afterglow Physics and the VHE Domain

Cited by 25 publications

References 186 publications

Localisation of gamma-ray bursts from the combined SpIRIT+HERMES-TP/SP nano-satellite constellation

Localisation of gamma-ray bursts from the combined SpIRIT+HERMES-TP/SP nano-satellite constellation

Hybrid Emission Modeling of GRB 221009A: Shedding Light on TeV Emission Origins in Long GRBs

External Inverse-compton and Proton Synchrotron Emission from the Reverse Shock as the Origin of VHE Gamma Rays from the Hyper-bright GRB 221009A

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