JET BREAKS AND ENERGETICS OF Swift GAMMA-RAY BURST X-RAY AFTERGLOWS

By J. Racusin, E. Liang, D. Burrows, A. Falcone, T. Sakamoto, Binbin Zhang, Bing Zhang, P. Evans, J. Osborne. 2008

229 citations recorded by the source corpus.

We present a systematic temporal and spectral study of all Swift-X-ray Telescope observations of gamma-ray burst (GRB) afterglows discovered between 2005 January and 2007 December. After constructing and fitting all light curves and spectra to power-law models, we classify the components of each afterglow in terms of the canonical X-ray afterglow and test them against the closure relations of the forward shock models for a variety of parameter combinations. The closure relations are used to identify potential jet breaks with characteristics including the uniform jet model with and without lateral spreading and energy injection, and a power-law structured jet model, all with a range of parameters. With this technique, we survey the X-ray afterglows with strong evidence for jet breaks (∼12% of our sample), and reveal cases of potential jet breaks that do not appear plainly from the light curve alone (another ∼30%), leading to insight into the missing jet break problem. Those X-ray light curves that do not show breaks or have breaks that are not consistent with one of the jet models are explored to place limits on the times of unseen jet breaks. The distribution of jet break times ranges from a few hours to a few weeks with a median of ∼1 day, similar to what was found pre-Swift. On average, Swift GRBs have lower isotropic equivalent γ-ray energies, which in turn result in lower collimation corrected γ-ray energies than those of pre-Swift GRBs. Finally, we explore the implications for GRB jet geometry and energetics.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/e1d9d8e54531911baf3c71b0514b3c17c005aa26

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In Astronomy and Astrophysics

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

Citations in the corpus

• The prompt-afterglow connection in gamma-ray bursts: a comprehensive statistical analysis of Swift X-ray light curves (2012, background): “Contrary to expectations, observations are often consistent with a constant density environment (ISM) also in the case of long GRBs (e.g. Racusin et al. 2009).”
• The physics of gamma-ray bursts & relativistic jets (2014, background): “Both Eγ and EK are found to have a much wider distribution than the pre-Swift sample [30,516,31].”
• THE COSMIC RATE, LUMINOSITY FUNCTION, AND INTRINSIC CORRELATIONS OF LONG GAMMA-RAY BURSTS (2009, background): “Given apparent challenges in inferring beaming from imaging observations of X-ray and optical afterglows (e.g., Racusin et al. 2009, and references therein), it may be most fruitful to focus on late-time radio observations (e.g., Cenko et al. 2009c).”
• A DECADE OF SHORT-DURATION GAMMA-RAY BURST BROADBAND AFTERGLOWS: ENERGETICS, CIRCUMBURST DENSITIES, AND JET OPENING ANGLES (2015, background): “Nearly two decades of long-duration GRB afterglow observations established a median beaming-corrected kinetic energy release of≈ 1051 erg (Frail et al. 2001; Berger et al. 2003; Friedman & Bloom 2005; Gehrels et al. 2008; Nysewander et al. 2009; Laskar et al. 2014), circumburst densities of≈ 0.1 − 1”
• An Embedded X-Ray Source Shines through the Aspherical AT 2018cow: Revealing the Inner Workings of the Most Luminous Fast-evolving Optical Transients (2018, methodology): “We use p=2.5 and explore the parameter space for two jets of θj=5° and θj=30°, representative of strongly collimated and less collimated outflows, respectively (as found for normal GRBs and low-energy GRBs; e.g., Racusin et al. 2009; Margutti et al. 2013b; Ryan et al. 2015).”
• A NEW POPULATION OF ULTRA-LONG DURATION GAMMA-RAY BURSTS (2013, background): “Strictly speaking this is dependent on the sensitivity and bandpass of the detecting instrument. supermassive black hole (e.g. Levan et al. 2011; Bloom et al. 2011; Burrows et al. 2011; Zauderer et al. 2011b).”
• THE AFTERGLOW OF GRB 130427A FROM 1 TO 1016 GHz (2013, background): “Limits on the Collimation-Corrected Energetics As seen in many other Swift GRBs (Racusin et al. 2009), the afterglow of GRB130427A shows no break in the XRT light curve in observations taken to date indicative of a jet.”
• A RADIO-SELECTED SAMPLE OF GAMMA-RAY BURST AFTERGLOWS (2011, result): “This distribution is similar to the previous studies (e.g., Racusin et al. 2009).”
• AFTERGLOW OBSERVATIONS OF FERMI LARGE AREA TELESCOPE GAMMA-RAY BURSTS AND THE EMERGING CLASS OF HYPER-ENERGETIC EVENTS (2010, background): “Second, there has been a dearth of measurements of jet opening angles (e.g., Panaitescu 2007; Kocevski & Butler 2008; Liang et al. 2008; Racusin et al. 2009) and well-sampled multiwavelength GRB afterglows (used to derived the afterglow kinetic energy EKE).”
• Methods and results of an automatic analysis of a complete sample of Swift-XRT observations of GRBs (2008, background): “For a targeted study of potential jet breaks in any light curve morphology, see Racusin et al. 2009).”
• DISCERNING THE PHYSICAL ORIGINS OF COSMOLOGICAL GAMMA-RAY BURSTS BASED ON MULTIPLE OBSERVATIONAL CRITERIA: THE CASES OF z = 6.7 GRB 080913, z = 8.2 GRB 090423, AND SOME SHORT/HARD GRBs (2009, background): “Furthermore, the inferred total energies (after beaming correction) are found to a have larger scatter than the pre-Swift sample (Liang et al. 2008; Kocevski & Butler 2008; Racusin et al. 2009).”
• THE STAR FORMATION RATE IN THE REIONIZATION ERA AS INDICATED BY GAMMA-RAY BURSTS (2009, background): “…resulting in GRBs, with the ability to observe the GRB and obtain a redshift (0 < F (z) < 1), the fraction of GRBs unobservable due to beaming (〈fbeam〉; e.g., Racusin et al. 2009; Cenko et al. 2009), and the comoving volume per unit redshift9 as dṄ dz = F (z) E(z) ρ̇∗(z) 〈fbeam〉 dV/dz 1 + z .”