A Study of the Afterglows of Four GRBs: Constraining the Explosion and Fireball Model

By S. Yost, F. Harrison, R. Sari, D. Frail. 2003

226 citations recorded by the source corpus.

We employ a fireball model of the GRB explosion to constrain intrinsic and environmental parameters of four events with good broadband afterglow data; GRB970508, GRB980329, GRB980703, and GRB000926. Using standard assumptions of constant circumburst density and no evolution of the fraction of the explosion energy in the post-shock magnetic field, we investigate the uniformity of the derived explosion and shock physics parameters among the events. We find densities that range from those of the ISM to diffuse clouds, energies comparable to the total GRB gamma-ray energy, collimations from near-isotropy to 0.04 rad, substantial electron energy fractions of 10-30% with energy distribution indices of 2.1-2.9 and magnetic energy fractions from 0.2-25%. We also investigate the level to which the data constrain standard model assumptions, such as the magnetic field evolution, and the allowed density profiles of the medium. Fits generally improve slightly with an increasing magnetic energy fraction epB. Good fits can be produced with epB accumulating or decaying with the shock strength over the afterglow as epB~gamma^x; -2<=x<=+1. The data are not very sensitive to increasing density profiles, allowing good fits even with density ~r^10. Some parameter values change by up to an order of magnitude under altered assumptions; parameters of even good fits cannot be taken at face value. The data are sensitive to decreasing densities; r^-2 profiles may produce reasonable fits; steeper profiles, even r^-2.5, will not fit the data.

Subfields: Astronomy and Astrophysics, Instrumentation, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/29cc6143af2bd7443b23922b65620a2fd17106e6

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In Astronomy and Astrophysics

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

In Instrumentation

1. Bing Zhang
2. E. Liang
3. E. Berger
4. Pawan Kumar
5. P. Lasky
6. Binbin Zhang
7. W. Fong
8. T. Piran

In Nuclear and High Energy Physics

1. Bing Zhang
2. E. Berger
3. Pawan Kumar
4. D. Giannios
5. M. Petropoulou
6. L. Sironi
7. E. Nakar
8. E. Liang

Citations in the corpus

• A RADIO-SELECTED SAMPLE OF GAMMA-RAY BURST AFTERGLOWS (2011, methodology): “The GRB parameters that we used here are good averages from the afterglow broadband modeling (Panaitescu & Kumar 2001; Yost et al. 2003).”
• AFTERGLOW OBSERVATIONS OF FERMI LARGE AREA TELESCOPE GAMMA-RAY BURSTS AND THE EMERGING CLASS OF HYPER-ENERGETIC EVENTS (2010, methodology): “…we have not yet accounted for additional sources of energy, including (nonrelativistic) SN emission, radiative losses at early times due to bright X-ray flares (Burrows et al. 2005a; Falcone et al. 2007), and synchrotron losses during the later phases of afterglow evolution (Yost et al. 2003).”
• Short-hard gamma-ray bursts (2007, background): “In long GRBs these parameters are reasonably constrained (e.g., Panaitescu & Kumar, 2001; Yost et al. , 2003) and so is the requirement that the magnetic field is sustained long after the shock (∼ 108λs, where λs is the plasma skin depth; Rossi & Rees, 2003).”
• 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): “Although Type I GRBs are expected to reside in such a medium, some Gold-Sample Type II GRBs have been found to reside in a constant medium as well (Panaitescu & Kumar 2002; Yost et al. 2003).”
• A complete reference of the analytical synchrotron external shock models of gamma-ray bursts (2013, background): “This is because the radiative loss fraction is at most ǫe (for fast cooling), which is constrained to be around 0.1 and lower (Panaitescu and Kumar, 2001, 2002; Yost et al., 2003)5.”
• Gamma-Ray Bursts in the Swift Era (2007, background): “Do microphysics parameters evolve with time (e.g., Yost et al. 2003; Ioka et al. 2006; Panaitescu et al. 2006b; Fan & Piran 2006a)?”
• A DECADE OF SHORT-DURATION GAMMA-RAY BURST BROADBAND AFTERGLOWS: ENERGETICS, CIRCUMBURST DENSITIES, AND JET OPENING ANGLES (2015, background): “In some cases, the radial density profiles of their circumburst environments reflect the wind environments expected for massive stars (Chevalier & Li 2000; Yost et al. 2003).”
• A Comprehensive Analysis of Swift XRT Data. III. Jet Break Candidates in X-Ray and Optical Afterglow Light Curves (2007, background): “Previous broadband fits and statistical analyses suggest that e is typically around 0.1 (Wijers & Galama 1999; Panaitescu & Kumar 2002; Yost et al. 2003; Liang et al. 2004; Wu et al. 2004).10 Therefore, we take e = 0.1 for all the bursts.”
• Physical Processes Shaping Gamma-Ray Burst X-Ray Afterglow Light Curves: Theoretical Implications from the Swift X-Ray Telescope Observations (2005, methodology): “Previous analyses using late-time afterglow data (e.g., Panaitescu & Kumar 2002; Yost et al. 2003) have also suggested that most afterglow data are consistent with an ISMmodel rather than a windmodel.”
• Short-Duration Gamma-Ray Bursts (2013, background): “…energy scale of ∼ 1051 erg (Frail et al. 2001; Bloom, Frail & Sari 2001; Berger, Kulkarni & Frail 2003), and a typical circumburst density of∼ 1 − 10 cm−3 with evidence for mass loss from the massive progenitor stars in some cases (Chevalier & Li 2000, Panaitescu & Kumar 2002, Yost et al. 2003).”
• The physics of gamma-ray bursts & relativistic jets (2014, background): “The full expression for the peak specific flux for these two types of CBM media are (e.g. Granot and Sari, 2002; Yost et al., 2003) fν,max = 1.6 mJy (1 + z) 1/2 B,−2E52n 1/2 p D −2 L,28, np ∝ R0 (79) fν,max = 7.7 mJy (p+ 0.12)(1 + z) 3/2 1/2 B,−2E52A∗D −2 L,28t −1/2 obs,d, np ∝ R−2.”
• Relativistic Jets Shine through Shocks or Magnetic Reconnection (2015, background): “GRBs have efficiency f ∼ 0.1 − 1 in converting jet power into gamma-ray (prompt) emission (e.g., Berger et al.2000; Panaitescu & Kumar 2002; Yost et al. 2003; Granot et al. 2006; Nava et al. 2013).”
• THE MILLISECOND MAGNETAR CENTRAL ENGINE IN SHORT GRBs (2015, methodology): “In our calculations, the microphysics parameters of the shocks are assigned to standard values derived from the observations (e.g. Panaitescu & Kumar 2002; Yost et al. 2003): ǫe=0.1 and ǫB = 0.01.”
• The Early X-Ray Emission from GRBs (2006, methodology): “We adopt the ISM model as the light curves for most GRBs appear consistent with the presence of a fairly constant density medium (e.g. Panaitescu & Kumar 2002, Yost et al. 2003, Blustin et al. 2006).”
• Gamma‐ray burst efficiency and possible physical processes shaping the early afterglow (2006, background): “Yost et al. (2003) and Ioka et al (2005) considered afterglow emission assuming ǫB and ǫe are timedependent, respectively.”
• COSMOLOGICAL IMPLICATIONS OF FAST RADIO BURST/GAMMA-RAY BURST ASSOCIATIONS (2013, methodology): “…on the above equations, we calculate the rest frame GRB DM value, DMGRB,z for a set of typical values of GRB parameters (Panaitescu & Kumar 2002; Yost et al. 2003; Zhang & Mészáros 2004): r1 = 10 7 cm, Eiso = 10 53 erg, Γ0 = 300 (so that M0 = 3.7 × 10 29 g), δt = 500 s, n = 1 cm−3 (ISM) and…”
• The Afterglow, Energetics, and Host Galaxy of the Short-Hard Gamma-Ray Burst 051221a (2006, result): “This is consistent with the values inferred for long-duration GRBs (Yost et al. 2003; Panaitescu & Kumar 2002).”