Variabilities of Gamma-Ray Burst Afterglows: Long-acting Engine, Anisotropic Jet, or Many Fluctuating Regions?

By K. Ioka, S. Kobayashi, Bing Zhang. 2004

145 citations recorded by the source corpus.

We show that simple kinematic arguments can give limits on the timescale and amplitude of variabilities in gamma-ray burst (GRB) afterglows, especially when the variability timescale is shorter than the observed time since the burst, Δt < t. These limits help us to identify the sources of afterglow variability. The afterglows of GRB 011211 and GRB 021004 marginally violate these limits. If such violation is confirmed by the Swift satellite, a possible explanation is that (1) the compact objects that power GRB jets continue to eject an intermittent outflow for a very long timescale (≳1 day), (2) the GRB jet from the central engine has a temporal anisotropy with a large brightness contrast ≳10 and small angular structure ≲10-2, or (3) many (≳103) regions fluctuate simultaneously in the emitting site.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/fa7867c3c225e1c70da0835ff578afafaecaa2e0

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. Bing Zhang
2. E. Berger
3. Pawan Kumar
4. E. Liang
5. Binbin Zhang
6. B. Metzger
7. Xuefeng Wu
8. D. Burrows

In Instrumentation

1. Bing Zhang
2. E. Liang
3. Pawan Kumar
4. Binbin Zhang
5. E. Berger
6. D. Burrows
7. N. Gehrels
8. C. Guidorzi

Citations in the corpus

• Unveiling the origin of X-ray flares in gamma-ray bursts (2010, methodology): “The three limits shown with solid, dashed and dot-dashed lines have been computed according to equations (7) and (A2) of Ioka et al. (2005). flux during the flare ∆F with respect to the underlying continuum F versus the duration of the flare ∆t over the time of flare occurrence t, in analogy with…”
• The physics of gamma-ray bursts & relativistic jets (2014, background): “It is widely accepted that they are powered by late central engine activities [88,83,92,82,230,93,84,296,297].”
• Gamma-ray burst afterglows (2006, background): “Rather they are the manifestations of internal dissipations at later times, which requires restarting the GRB central engine (Burrows et al. 2005; Zhang et al. 2006; Fan & Wei 2005; Ioka et al. 2005; Wu et al. 2006; Falcone et al. 2006; Romano et al. 2006; Lazzati & Perna 2006).”
• A NEW POPULATION OF ULTRA-LONG DURATION GAMMA-RAY BURSTS (2013, background): “These temporal changes are unusual in GRB afterglows, but are rather typical in GRB prompt emission, which is seen to be highly variable, indeed the rapidity of the flux change, ∆t/t ∼ 0.01 in several cases, is typical of the expectations of ongoing prompt-like emission (e.g., Ioka et al. 2005).”
• Physical Processes Shaping Gamma-Ray Burst X-Ray Afterglow Light Curves: Theoretical Implications from the Swift X-Ray Telescope Observations (2005, background): “However, in such a case it is very hard to achieve a large contrast between the flares and the underlying afterglow level (Ioka et al. 2005).”
• Testing the Curvature Effect and Internal Origin of Gamma-Ray Burst Prompt Emissions and X-Ray Flares with Swift Data (2006, background): “…of the prompt emission or the corresponding X-ray flare, which is consistent with the expectation of the internal dissipation models for the prompt emission and X-ray flares (e.g. Burrows et al. 2005; Zhang et al. 2006a; Fan & Wei 2005; Ioka et al. 2005; Falcone et al. 2006; Romano et al. 2006).”
• Gamma-Ray Bursts in the Swift Era (2007, background): “Ioka et al. (2005) pointed out that some optical fluctuations are difficult to interpretwithin any external shock related schemes, and they require reactivation of the central engine.”
• A Comprehensive Analysis of Swift XRT Data. III. Jet Break Candidates in X-Ray and Optical Afterglow Light Curves (2007, background): “…such as energy transitions between different epochs (Kobayashi & Zhang 2007), evolution of microphysical parameters (Panaitescu et al. 2006; Ioka et al. 2005), and jet profiles (Zhang et al. 2004; 6 Note that the Bronze and Silver samples also include bursts that are detected in both the…”
• A complete reference of the analytical synchrotron external shock models of gamma-ray bursts (2013, background): “Swift observations suggest that X-ray flares observed in the afterglow phase can be best modeled as internal emission of late central engine activities (Burrows et al., 2005; Zhang et al., 2006; Fan and Wei, 2005; Ioka et al., 2005; Lazzati and Perna, 2007; Maxham and Zhang, 2009).”