Analytic Light Curves of Gamma-Ray Burst Afterglows: Homogeneous versus Wind External Media

By A. Panaitescu, Pawan Kumar. 2000

352 citations recorded by the source corpus.

Assuming an adiabatic evolution of a gamma-ray burst (GRB) remnant interacting with an external medium, we calculate the injection, cooling, and absorption break frequencies and the afterglow flux for plausible orderings of the break and observing frequencies. The analytical calculations are restricted to a relativistic remnant and, in the case of collimated ejecta, to the phase where there is an insignificant lateral expansion. Results are given for both a homogeneous external medium and a wind ejected by the GRB progenitor. We compare the afterglow emission at different observing frequencies, for each type of external medium. It is found that observations at submillimeter frequencies during the first day provide the best way of discriminating between the two models. By taking into account the effect of inverse Compton (IC) scatterings on the electron cooling, a new possible time dependence of the cooling break is identified. The signature of the upscattering losses could be seen in the optical synchrotron emission from a GRB remnant interacting with a preejected wind, as a temporary mild flattening of the afterglow decay. The upscattered radiation itself should be detected in the soft X-ray emission from GRB remnants running into denser external media, starting a few hours after the main event.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/6411507fb5e0d7c0a6b8ab164743529b29a7328a

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In Astronomy and Astrophysics

1. Bing Zhang
2. E. Berger
3. Pawan Kumar
4. E. Nakar
5. B. Metzger
6. P. Mészáros
7. E. Liang
8. T. Piran

Citations in the corpus

• On the generation of high-energy photons detected by the Fermi Satellite from gamma-ray bursts (2009, background): “Fortunately, it turns out that the observed flux at a frequencyν that is larger than all characteristic frequencies for the shocked gas, namely the synchrotron peak and cooling frequencies, is independent of these two highly uncertain parameters (Kumar 2000, Panaitescu & Kumar 2000).”
• Short-hard gamma-ray bursts (2007, methodology): “…radiation also upscatter synchrotron photons by the inverse Compton process (synchrotron self-Compton - SSC; e.g., Mészáros, Rees & Papathanassiou 1994; Waxman 1997c; Wei & Lu 1998, 2000; Panaitescu & Kumar 2000; Dermer, Chiang & Mitman 2000; Sari & Esin 2001; Zhang & Mészáros 2001b).”
• Probing the cosmic reionization history and local environment of gamma‐ray bursts through radio dispersion (2003, methodology): “The evaluation of the synchrotron self-absorption frequency is based on Granot, Piran & Sari (1999) and Panaitescu & Kumar (2000).”
• Jet Energy and Other Parameters for the Afterglows of GRB 980703, GRB 990123, GRB 990510, and GRB 991216 Determined from Modeling of Multifrequency Data (2001, neutral): “The synchrotron self-absorption frequency in the fluid rest frame is atν′a = ν ′(γa) with γa given by (see Panaitescu & Kumar 2000) γa = ( 5 e σe τe B )3/10 γ−1/2m .”
• The afterglow of GRB 021004: surfing on density waves (2002, background): “The code takes fully into account the light travel-time effects, and assumes standard synchrotron emission equations to compute the comoving frame intensity (Panaitescu & Kumar 2000; Granot & Sari 2002).”
• AFTERGLOW OBSERVATIONS OF FERMI LARGE AREA TELESCOPE GAMMA-RAY BURSTS AND THE EMERGING CLASS OF HYPER-ENERGETIC EVENTS (2010, background): “…continuous improvements and it has been well tested (Meszaros & Rees 1997; Sari et al. 1998, 1999; Wijers & Galama 1999; Chevalier & Li 2000; Panaitescu & Kumar 2000; Yost et al. 2003; Willingale et al. 2007), it still must make several simplifying assumptions about the shock dynamics,…”
• Theories of Gamma-Ray Bursts (2001, background): “Its effects on afterglows were considered by (Waxman 1997b), and observational manifestations in afterglows were investigated more carefully by Panaitescu & Kumar 2000 and Sari & Esin 2001.”
• The 2175 Å Dust Feature in a Gamma-Ray Burst Afterglow at Redshift 2.45 (2008, background): “Using Sari & Piran (1999), Panaitescu & Kumar (2000), and Molinari et al. (2007), we estimate 0 for the ISM case to 0 160 E53 / 0:2nð Þ1/8, and for the wind-shaped case to 0 80 E53 /ð 0:2A Þ1/4, both more in line with previous bursts and theoretical predictions.”
• REM observations of GRB 060418 and GRB 060607A: the onset of the afterglow and the initial fireball Lorentz factor determination (2006, background): “It is therefore possible to estimateΓdec (Sari & Piran 1999), which is expected to be half of the initial valueΓ0 (Panaitescu & Kumar 2000; Mészáros 2006).”
• Gamma-ray bursts in the comoving frame (2011, neutral): “6: Liso = 4 3 Γ2L′iso = εe 4 3 Γ2 dE′diss dt′ (8) where the dissipated comoving energyE′diss is given by (Panaitescu & Kumar 2000): E′diss = (Γ− 1)m(r)c 2 (9) Only a fractionεe of the dissipated energy is radiated.”
• The Shape of Spectral Breaks in Gamma-Ray Burst Afterglows (2001, background): “This effect is know to be important, whenǫB ≪ ǫe (Sari, Narayan & Piran 1996, Panaitescu & Kumar 2000, Sari & Esin 2001).”
• Gamma-Ray Bursts in the Swift Era (2007, background): “…produces significant GeV emission that is detectable by GLAST (e.g., Mészáros & Rees 1994; Dermer et al. 2000; Zhang & Mészáros 2001b, for more general discussion of SSC process in the external forward shock, see Wei & Lu 1998, 2000a; Panaitescu & Kumar 2000; Sari & Esin 2001; Wu et al 2005b).”
• High-Energy Spectral Components in Gamma-Ray Burst Afterglows (2001, background): “…in the observer frame) to the comoving radiation cooling time t′c = [(t ′ sy) −1 + (t′IC) −1]−1 = t′sy/(1 + Y ), where t ′ sy and t ′ IC are the synchrotron and the IC cooling time, and Y = t′sy/t ′ IC = (−1 + √ 1 + 4ηǫx/ǫB)/2 is the Compton factor (e.g. Panaitescu & Kumar 2000; Sari & Esin 2001).”