Afterglow observations of Fermi large area telescope gamma-ray bursts and the emerging class of hyper-energetic events

S. B. Cenko; D. A. Frail; F. A. Harrison; J. B. Haislip; D. E. Reichart; N. R. Butler; B. E. Cobb; A. Cucchiara; E. Berger; J. S. Bloom; P. Chandra; D. B. Fox; D. A. Perley; J. X. Prochaska; A. V. Filippenko; K. Glazebrook; K. M. Ivarsen; M. M. Kasliwal; S. R. Kulkarni; A. P. Lacluyze; S. Lopez; A. N. Morgan; M. Pettini; V. R. Rana

doi:10.1088/0004-637X/732/1/29

Afterglow observations of Fermi large area telescope gamma-ray bursts and the emerging class of hyper-energetic events

S. B. Cenko, D. A. Frail, F. A. Harrison, J. B. Haislip, D. E. Reichart, N. R. Butler, B. E. Cobb, A. Cucchiara, E. Berger, J. S. Bloom, P. Chandra, D. B. Fox, D. A. Perley, J. X. Prochaska, A. V. Filippenko, K. Glazebrook, K. M. Ivarsen, M. M. Kasliwal, S. R. Kulkarni, A. P. LacluyzeS. Lopez, A. N. Morgan, M. Pettini, V. R. Rana

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Abstract

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 (GRB090926A) exceeds the canonical value of 10⁵¹erg 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.

Original language	English (US)
Article number	29
Journal	Astrophysical Journal
Volume	732
Issue number	1
DOIs	https://doi.org/10.1088/0004-637X/732/1/29
State	Published - May 1 2011
Externally published	Yes

Keywords

cosmology: observations
gamma-ray burst: general
radio continuum: general

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.1088/0004-637X/732/1/29

Cite this

Cenko, S. B., Frail, D. A., Harrison, F. A., Haislip, J. B., Reichart, D. E., Butler, N. R., Cobb, B. E., Cucchiara, A., Berger, E., Bloom, J. S., Chandra, P., Fox, D. B., Perley, D. A., Prochaska, J. X., Filippenko, A. V., Glazebrook, K., Ivarsen, K. M., Kasliwal, M. M., Kulkarni, S. R., ... Rana, V. R. (2011). Afterglow observations of Fermi large area telescope gamma-ray bursts and the emerging class of hyper-energetic events. Astrophysical Journal, 732(1), Article 29. https://doi.org/10.1088/0004-637X/732/1/29

Cenko, SB, Frail, DA, Harrison, FA, Haislip, JB, Reichart, DE, Butler, NR, Cobb, BE, Cucchiara, A, Berger, E, Bloom, JS, Chandra, P, Fox, DB, Perley, DA, Prochaska, JX, Filippenko, AV, Glazebrook, K, Ivarsen, KM, Kasliwal, MM, Kulkarni, SR, Lacluyze, AP, Lopez, S, Morgan, AN, Pettini, M & Rana, VR 2011, 'Afterglow observations of Fermi large area telescope gamma-ray bursts and the emerging class of hyper-energetic events', Astrophysical Journal, vol. 732, no. 1, 29. https://doi.org/10.1088/0004-637X/732/1/29

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title = "Afterglow observations of Fermi large area telescope gamma-ray bursts and the emerging class of hyper-energetic events",

abstract = "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 (GRB090926A) exceeds the canonical value of 1051erg 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.",

keywords = "cosmology: observations, gamma-ray burst: general, radio continuum: general",

author = "Cenko, {S. B.} and Frail, {D. A.} and Harrison, {F. A.} and Haislip, {J. B.} and Reichart, {D. E.} and Butler, {N. R.} and Cobb, {B. E.} and A. Cucchiara and E. Berger and Bloom, {J. S.} and P. Chandra and Fox, {D. B.} and Perley, {D. A.} and Prochaska, {J. X.} and Filippenko, {A. V.} and K. Glazebrook and Ivarsen, {K. M.} and Kasliwal, {M. M.} and Kulkarni, {S. R.} and Lacluyze, {A. P.} and S. Lopez and Morgan, {A. N.} and M. Pettini and Rana, {V. R.}",

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language = "English (US)",

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T1 - Afterglow observations of Fermi large area telescope gamma-ray bursts and the emerging class of hyper-energetic events

AU - Cenko, S. B.

AU - Frail, D. A.

AU - Harrison, F. A.

AU - Haislip, J. B.

AU - Reichart, D. E.

AU - Butler, N. R.

AU - Cobb, B. E.

AU - Cucchiara, A.

AU - Berger, E.

AU - Bloom, J. S.

AU - Chandra, P.

AU - Fox, D. B.

AU - Perley, D. A.

AU - Prochaska, J. X.

AU - Filippenko, A. V.

AU - Glazebrook, K.

AU - Ivarsen, K. M.

AU - Kasliwal, M. M.

AU - Kulkarni, S. R.

AU - Lacluyze, A. P.

AU - Lopez, S.

AU - Morgan, A. N.

AU - Pettini, M.

AU - Rana, V. R.

PY - 2011/5/1

Y1 - 2011/5/1

N2 - 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 (GRB090926A) exceeds the canonical value of 1051erg 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.

AB - 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 (GRB090926A) exceeds the canonical value of 1051erg 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.

KW - cosmology: observations

KW - gamma-ray burst: general

KW - radio continuum: general

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ER -

Afterglow observations of Fermi large area telescope gamma-ray bursts and the emerging class of hyper-energetic events

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