Vlbi and Archival Vla and WSRT Observations of the GRB 030329 Radio Afterglow

Mesler, Robert A.; Pihlström, Y. M.; Taylor, G. B.; Granot, Jonathan

doi:10.1088/0004-637x/759/1/4

Cited by 22 publications

(55 citation statements)

References 42 publications

(77 reference statements)

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“…This upper limit is consistent with the picture that in order to see the prompt γ -ray emission our line of sight should be within the initial jet aperture, in which case the cumulative proper motion of the flux centroid is indeed expected to be less than the current radius (i.e. half the diameter) of the image (Granot & Loeb 2003;Pihlström et al 2007;Mesler et al 2012), or Table 1. Angular scales, time scales, and modulation indices for weak, refractive, and diffractive ISS, with ν 0 the transition frequency between weak and strong scattering, θ F0 the angular size of the first Fresnel zone at this frequency, ν the observing frequency, and θ s the source angular size.…”

Section: Very Long Baseline Interferometrysupporting

confidence: 86%

“…Evolution of the source size of GRB 030329. All the solid symbols are size measurements or upper limits obtained with VLBI (Taylor et al 2004;Pihlström et al 2007;Mesler et al 2012), while the open symbol indicates an estimate based on scintillation effects (Berger et al 2003a). observations there have been two more source size measurements, at 217 d ) and 806 d (Pihlström et al 2007), and a constraining upper limit at 2032 d, i.e.…”

Section: Very Long Baseline Interferometrymentioning

confidence: 99%

“…Besides the size measurements, constraints on the proper motion have also been placed by the VLBI observations: <0.07 mas/yr using the latest VLBI observation, implying an upper limit <0.73 c (Mesler et al 2012). This upper limit is consistent with the picture that in order to see the prompt γ -ray emission our line of sight should be within the initial jet aperture, in which case the cumulative proper motion of the flux centroid is indeed expected to be less than the current radius (i.e.…”

Section: Very Long Baseline Interferometrymentioning

confidence: 99%

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Gamma-Ray Burst Jets and their Radio Observations

Granot

Horst

2014

Publ. Astron. Soc. Aust.

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Radio observations play a key role in studying the jets that power GRBs, the most luminous cosmic explosions. They are crucial for determining the GRB jet energy, the external density, and the microphysical parameters of relativistic collisionless shocks, from afterglow broadband modeling. Radio image size measurements are rare, but provide extremely useful information. The "radio flare" peaking after ß1 day helps constrain the magnetisation and magnetic-field structure of GRB outflows. This review discusses the current observational and modeling status, focusing on the afterglow and outlining prompt radio emission searches, along with recent theoretical progress in GRB jet dynamics, focusing on magnetic acceleration, jet propagation inside a massive star progenitor (for long GRBs), the reverse shock, and the late afterglow. Great progress has been made in our understanding of magnetic acceleration, collimation and later sideways expansion of GRB jets, with interesting implications for the prompt, reverse shock, and afterglow emission. We outline how theory and observations were combined to study GRB jet physics and their immediate environment. Finally, potential paths are suggested for combining theory and observations to achieve greater progress, and some prospects for the future are discussed in light of the expected improvements in observational capabilities and theoretical advances.

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Section: Very Long Baseline Interferometrysupporting

confidence: 86%

Section: Very Long Baseline Interferometrymentioning

confidence: 99%

Section: Very Long Baseline Interferometrymentioning

confidence: 99%

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Gamma-Ray Burst Jets and their Radio Observations

Granot

Horst

2014

Publ. Astron. Soc. Aust.

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“…In fact, the counterjet rebrightening appears much shallower in our model (solid black line in the top panel) than in the prescription by Frail et al (2000;dashed black curve). This might explain the absence of clear counterjet signatures in the late-time radio afterglow of GRB 030329 (Mesler et al 2012). Yet, this would require a relatively small electron acceleration efficiency ( e 0.01).…”

Section: Resultsmentioning

confidence: 98%

A Late-Time Flattening of Light Curves in Gamma-Ray Burst Afterglows

Sironi

Giannios

2013

ApJ

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The afterglow emission from gamma-ray bursts (GRBs) is usually interpreted as synchrotron radiation from relativistic electrons accelerated at the GRB external shock. We investigate the temporal decay of the afterglow emission at late times, when the bulk of the shock-accelerated electrons are non-relativistic (the "deep Newtonian phase," as denoted by Huang and Cheng). We assume that the electron spectrum in the deep Newtonian phase is a power-law distribution in momentum with slope p, as dictated by the theory of Fermi acceleration in nonrelativistic shocks. For a uniform circumburst medium, the deep Newtonian phase begins at t DN ∼ 3 5/6 e,−1 t ST , where t ST marks the transition of the blast wave to the non-relativistic, spherically symmetric Sedov-Taylor (ST) solution, and e = 0.1 e,−1 quantifies the amount of shock energy transferred to the electrons. For typical parameters, the deep Newtonian stage starts ∼0.5 to several years after the GRB. The radio flux in this phase decays as F ν ∝ t −3(p+1)/10 ∝ t −(0.9÷1.2) , for a power-law slope 2 < p < 3. This is shallower than the scaling F ν ∝ t −3(5p−7)/10 ∝ t −(0.9÷2.4) derived by Frail et al., which only applies if the GRB shock is non-relativistic, but the electron distribution still peaks at ultra-relativistic energies (a regime that is relevant for a narrow time interval, and only if t DN t ST , namely, e 0.03). We discuss how the deep Newtonian phase can be reliably used for GRB calorimetry, and we comment on the good detection prospects of trans-relativistic blast waves at 0.1 ÷ 10 GHz with the Karl G. Jansky Very Large Array and LOw-Frequency ARray.

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“…It is the only GRB up to now for which the source size has been measured with VLBI, and the radio afterglow was so bright and long-lasting that it has been detected for almost a decade at low radio frequencies (van der Horst et al 2008;Mesler et al 2012). The multi-frequency light curves have made it possible to follow the evolution of the blast wave from the ultra-relativistic to the non-relativistic phase and perform broadband modeling in the different phases.…”

Section: Progress In the Last Decadementioning

confidence: 99%

The SKA View of Gamma-Ray Bursts

Burlon¹,

Ghirlanda²,

Horst³

et al. 2015

Proceedings of Advancing Astrophysics With the Square Kilometre Array — PoS(AASKA14)

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Gamma-ray bursts (GRBs) are some of the most extreme events in the Universe. As well as providing a natural laboratory for investigating fundamental physical processes, they might trace the cosmic star formation rate up to extreme redshifts and probe the composition of the intergalactic medium over most of the Universe's history. Radio observations of GRBs play a key part in determining their physical properties, but currently they are largely limited to follow-up observations of γ-ray-detected objects. The SKA will significantly increase our ability to study GRB afterglows, following up several hundred objects in the high frequency bands already in the "early science" implementation of the telescope. SKA1-MID Bands 4 (4 GHz) and 5 (9.2 GHz) will be particularly suited to the detection of these transient phenomena. The SKA will trace the peak of the emission, sampling the thick-to-thin transition of the evolving spectrum, and follow-up the afterglow down to the time the ejecta slow down to non-relativistic speeds. The full SKA will be able to observe the afterglows across the non-relativistic transition, for ∼ 25% of the whole GRB population. This will allow us to get a significant insight into the true energy budget of GRBs, probe their surrounding density profile, and the shock microphysics. The SKA will also be able to routinely detect the elusive "orphan afterglow" emission, from the population of GRBs whose jets are not pointed towards the Earth. We expect that a deep all-sky survey such as SKA1-SUR will see around 300 orphan afterglows every week. We predict these detection to be ∼ > 1000 when the full SKA telescope will be operational.Advancing Astrophysics with the Square Kilometre Array

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Vlbi and Archival Vla and WSRT Observations of the GRB 030329 Radio Afterglow

Cited by 22 publications

References 42 publications

Gamma-Ray Burst Jets and their Radio Observations

Gamma-Ray Burst Jets and their Radio Observations

A Late-Time Flattening of Light Curves in Gamma-Ray Burst Afterglows

The SKA View of Gamma-Ray Bursts

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