AFTERGLOW OBSERVATIONS OF FERMI LARGE AREA TELESCOPE GAMMA-RAY BURSTS AND THE EMERGING CLASS OF HYPER-ENERGETIC EVENTS

By S. Cenko, D. Frail, F. Harrison, J. Haislip, D. Reichart, N. Butler, B. Cobb, A. Cucchiara, E. Berger, Joshua S. Bloom and 14 more. 2010

142 citations recorded by the source corpus.

We present broadband (radio, optical, and X-ray) light curves and spectra of the afterglows of four long-duration gamma-ray bursts (GRBs; GRBs 090323, 090328, 090902B, and 090926A) detected by the Gamma-Ray Burst Monitor and Large Area Telescope (LAT) instruments on the Fermi satellite. With its wide spectral bandpass, extending to GeV energies, Fermi is sensitive to GRBs with very large isotropic energy releases (1054 erg). Although rare, these events are particularly important for testing GRB central-engine models. When combined with spectroscopic redshifts, our afterglow data for these four events are able to constrain jet collimation angles, the density structure of the circumburst medium, and both the true radiated energy release and the kinetic energy of the outflows. In agreement with our earlier work, we find that the relativistic energy budget of at least one of these events (GRB 090926A) exceeds the canonical value of 1051 erg by an order of magnitude. Such energies pose a severe challenge for models in which the GRB is powered by a magnetar or a neutrino-driven collapsar, but remain compatible with theoretical expectations for magnetohydrodynamical collapsar models (e.g., the Blandford–Znajek mechanism). Our jet opening angles (θ) are similar to those found for pre-Fermi GRBs, but the large initial Lorentz factors (Γ0) inferred from the detection of GeV photons imply θΓ0 ≈ 70–90, values which are above those predicted in magnetohydrodynamic models of jet acceleration. Finally, we find that these Fermi-LAT events preferentially occur in a low-density circumburst environment, and we speculate that this might result from the lower mass-loss rates of their lower-metallicity progenitor stars. Future studies of Fermi-LAT afterglows at radio wavelengths with the order-of-magnitude improvement in sensitivity offered by the Extended Very Large Array should definitively establish the relativistic energy budgets of these events.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/7918fe729e06ce8459070cf932a42204f730b737

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. B. Metzger
3. E. Berger
4. B. Margalit
5. W. Fong
6. E. Quataert
7. D. Kasen
8. Raffaella Margutti

In Nuclear and High Energy Physics

1. E. Berger
2. Bing Zhang
3. B. Metzger
4. E. Orlando
5. B. Margalit
6. E. Quataert
7. F. Ryde
8. Troy A. Porter

Citations in the corpus

• A DECADE OF SHORT-DURATION GAMMA-RAY BURST BROADBAND AFTERGLOWS: ENERGETICS, CIRCUMBURST DENSITIES, AND JET OPENING ANGLES (2015, background): “…17 events with limits (Frail et al. 2001; Berger et al. 2003; Bloom et al. 2003; Ghirlanda et al. 2004; Friedman & Bloom 2005; Racusin et al. 2009; Cenko et al. 2010, 2011; Filgas et al. 2011; Goldstein et al. 2011; Ryan et al. 2015) and calculate the cumulative distributions in the same manner…”
• Detection of a Spectral Break in the Extra Hard Component of GRB 090926A (2011, background): “Cenko et al. (2010) analyzed the observed late optical and X-ray afterglows of GRB 090926A and showed that they can be explained by synchrotron emission from the adiabatic forward shock propagating into the wind medium with Aext ≃ 3.4 × 1011 g cm−1.”
• A RADIO-SELECTED SAMPLE OF GAMMA-RAY BURST AFTERGLOWS (2011, unknown): “…(58) http://space.mit.edu/HETE/Bursts/; (59) http://www.swift.ac.uk/xrt_curves/; (60) Bradt et al. 2001; (61) Bloom et al. 2003; (62) Cenko et al. 2011; (63) McBreen et al. 2010; (64) Cucchiara et al. 2011; (65) Berger et al. 2003a; (66) Greiner et al. 2003; (67) Christensen et…”
• The diversity of transients from magnetar birth in core collapse supernovae (2015, background): “In a similar way, the gammaray and afterglow kinetic energies of the brightest LGRBs detected by Fermi are inferred to approach or exceed a few 1052 ergs (Cenko et al. 2011).”
• Short-Duration Gamma-Ray Bursts (2013, background): “…a two orders of magnitude downward correctionin the energy scale, with a resulting typical value ofEγ ∼ EK ∼ few× 1051 erg (Bloom, Frail & Sari 2001; Frail et al. 2001; Berger, Kulkarni & Frail 2003), albeit with a spread of about an order of magnitude (Soderberg et al. 2006b, Cenko et al. 2011).”