Fermi-LAT Observations of the Gamma-Ray Burst GRB 130427A

Ackermann, M.; Ajello, M.; Asano, Katsuaki; Atwood, W. B.; Axelsson, M.; Baldini, Luca; Ballet, J.; Barbiellini, G.; Baring, Matthew G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Bissaldi, E.; Bonamente, E.; Bregeon, J.; Brigida, M.; Bruel, Pascal; Buehler, R.; Burgess, J. Michael; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Cecchi, C.; Chaplin, V.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cleveland, W. H.; Cohen-Tanugi, J.; Collazzi, A. C.; Cominsky, L.; Connaughton, V.; Conrad, J.; Cutini, S.; D’Ammando, F.; Angelis, A. De; Deklotz, M.; Palma, F. de; Dermer, C. D.; Desiante, R.; Diekmann, A.; Venere, L. Di; Drell, P. S.; Drlica-Wagner, A.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Finke, J.; Fitzpatrick, G.; Focke, W. B.; Franckowiak, A.; Fukazawa, Yasushi; Funk, S.; Fusco, P.; Gargano, F.; Gehrels, N.; Germani, S.; Gibby, M. H.; Giglietto, N.; Giles, M. M.; Giordano, F.; Giroletti, M.; Godfrey, G.; Granot, Jonathan; Grenier, I. A.; Grove, J. E.; Gruber, D.; Guiriec, S.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hays, E.; Horan, D.; Hughes, R. E.; Inoue, Yoshiyuki; Jogler, T.; Jóhannesson, G.; Johnson, W. N.; Kawano, Takafumi; Knödlseder, J.; Kocevski, D.; Kuss, M.; Landé, J.; Larsson, Stefan; Latronico, L.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; Michelson, P. F.; Mizuno, T.; Моисеев, А. А.; Monzani, M. E.; Moretti, E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nemmen, R.; Nuss, E.; Ohno, M.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orienti, M.; Paneque, D.; Pelassa, V.; Perkins, J. S.; Pesce-Rollins, M.; Petrosian, V.; Piron, F.; Pivato, G.; Porter, T. A.; Racusin, J. L.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Ritz, S.; Roth, M.; Ryde, F.; Sartori, A.; Parkinson, P. M. Saz; Scargle, Jeffrey D.; Schulz, A.; Sgrò, C.; Siskind, E. J.; Сонбас, Э.; Spandre, G.; Spinelli, P.; Tajima, H.; Takahashi, H.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Usher, T.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vitale, V.; Winer, B. L.; Wood, K. S.; Yamazaki, Ryo; Younes, George; Yu, H. F.; Zhu, S. J.; Bhat, P. N.; Briggs, M. S.; Byrne, Dave; Foley, S.; Goldstein, A.; Jenke, P.; Kippen, R. M.; Kouveliotou, C.; McBreen, S.; Meegan, C.; Pačiesas, W. S.; Preece, R.; Rau, A.; Tierney, D.; Horst, A. J. van der; Kienlin, A. von; Wilson-Hodge, C.; Xiong, S. L.; Cusumano, G.; Parola, V. La; Cummings, J. R.

doi:10.1126/science.1242353

Cited by 282 publications

(269 citation statements)

References 39 publications

(24 reference statements)

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“…GRB 120711A and GRB 130427A (e.g. Laskar et al 2013;Perley et al 2014;Preece et al 2014;Vestrand et al 2014;Ackermann et al 2014) are two powerful bursts with E γ,iso ∼ 10 54 erg in the 1 keV−10 MeV energy range (about one order of magnitude higher than that estimated for GRB 041219A (McBreen et al 2006;Götz et al 2011)) and long-lived soft γ-ray afterglow emission (∼10 ks for GRB 120711A and ∼1 ks for GRB 130427A). The soft γ-ray detection from GRB 130427A is most likely limited by the Swift/BAT sensitivity considering that the LAT emission was detectable for longer than a day.…”

Section: Grb 120711a As a Member Of The Long Grb Populationmentioning

confidence: 99%

GRB 120711A: an intense INTEGRAL burst with long-lasting softγ-ray emission and a powerful optical flash

Martín-Carrillo

Hanlon

Topinka

et al. 2014

A&A

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A long and intense γ-ray burst (GRB) was detected by INTEGRAL on 11 July 2012 with a duration of ∼115 s and fluence of 2.8 × 10 −4 erg cm −2 in the 20 keV−8 MeV energy range. GRB 120711A was at z ∼ 1.405 and produced soft γ-ray emission (>20 keV) for at least ∼10 ks after the trigger. The GRB was observed by several ground-based telescopes that detected a powerful optical flash peaking at an R-band brightness of ∼11.5 mag at ∼126 s after the trigger, or ∼9th magnitude when corrected for the host galaxy extinction (A V ∼ 0.85). The X-ray afterglow was monitored by the Swift, XMM-Newton, and Chandra observatories from 8 ks to 7 Ms and provides evidence for a jet break at ∼0.9 Ms. We present a comprehensive temporal and spectral analysis of the long-lasting soft γ-ray emission detected in the 20−200 keV band with INTEGRAL/IBIS, the Fermi/LAT post-GRB detection above 100 MeV, the soft X-ray afterglow and the optical/near-infrared detections from Watcher, Skynet/PROMPT, GROND, and REM. The prompt emission had a very hard spectrum (E peak ∼ 1 MeV) and yields an E γ,iso ∼ 10 54 erg (1 keV−10 MeV rest frame), making GRB 120711A one of the most energetic GRBs detected so far. We modelled the long-lasting soft γ-ray emission using the standard afterglow scenario, which indicates a forward shock origin. The combination of data extending from the near-infrared to GeV energies suggest that the emission is produced by a broken power-law spectrum consistent with synchrotron radiation. The afterglow is well modelled using a stratified wind-like environment with a density profile k ∼ 1.2, suggesting a massive star progenitor (i.e. Wolf-Rayet) with a mass-loss rate between ∼10 −5 −10 −6 M yr −1 depending on the value of the radiative efficiency (η γ = 0.2 or 0.5). The analysis of the reverse and forward shock emission reveals an initial Lorentz factor of ∼120−340, a jet half-opening angle of ∼2 • −5 • , and a baryon load of ∼10 −5 −10 −6 M consistent with the expectations of the fireball model when the emission is highly relativistic. Long-lasting soft γ-ray emission from other INTEGRAL GRBs with high peak fluxes, such as GRB 041219A, was not detected, suggesting that a combination of high Lorentz factor, emission above 100 MeV, and possibly a powerful reverse shock are required. Similar long-lasting soft γ-ray emission has recently been observed from the nearby and extremely bright Fermi/LAT burst GRB 130427A.

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Section: Grb 120711a As a Member Of The Long Grb Populationmentioning

confidence: 99%

GRB 120711A: an intense INTEGRAL burst with long-lasting softγ-ray emission and a powerful optical flash

Martín-Carrillo

Hanlon

Topinka

et al. 2014

A&A

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“…When sufficient photon statistics were available, their GeV emission was also found to be harder than the extrapolation of their keV−MeV emission spectrum and was generally well described by a powerlaw spectral component with a photon index − 2. After the end of the keV−MeV prompt emission, this additional powerlaw component persists during hundreds of seconds, up to 19 h in the case of GRB 130427A (Ackermann et al 2014). Specifically, Ackermann et al (2013a) showed that the luminosity above 100 MeV decreases simply as L(t) ∝ t λ , with λ −1 at late times.…”

Section: Introductionmentioning

confidence: 99%

Time evolution of the spectral break in the high-energy extra component of GRB 090926A

Yassine

Piron

Mochkovitch

et al. 2017

A&A

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Aims. The prompt light curve of the long GRB 090926A reveals a short pulse ∼10 s after the beginning of the burst emission, which has been observed by the Fermi observatory from the keV to the GeV energy domain. During this bright spike, the high-energy emission from GRB 090926A underwent a sudden hardening above 10 MeV in the form of an additional power-law component exhibiting a spectral attenuation at a few hundreds of MeV. This high-energy break has been previously interpreted in terms of gamma-ray opacity to pair creation and has been used to estimate the bulk Lorentz factor of the outflow. In this article, we report on a new time-resolved analysis of the GRB 090926A broadband spectrum during its prompt phase and on its interpretation in the framework of prompt emission models. Methods. We characterized the emission from GRB 090926A at the highest energies with Pass 8 data from the Fermi Large Area Telescope (LAT), which offer a greater sensitivity than any data set used in previous studies of this burst, particularly in the 30−100 MeV energy band. Then, we combined the LAT data with the Fermi Gamma-ray Burst Monitor (GBM) in joint spectral fits to characterize the time evolution of the broadband spectrum from keV to GeV energies. We paid careful attention to the systematic effects that arise from the uncertainties on the LAT response. Finally, we performed a temporal analysis of the light curves and we computed the variability timescales from keV to GeV energies during and after the bright spike. Results. Our analysis confirms and better constrains the spectral break, which has been previously reported during the bright spike. Furthermore, it reveals that the spectral attenuation persists at later times with an increase of the break characteristic energy up to the GeV domain until the end of the prompt phase. We discuss these results in terms of keV−MeV synchroton radiation of electrons accelerated during the dissipation of the jet energy and inverse Compton emission at higher energies. We interpret the high-energy spectral break as caused by photon opacity to pair creation. Requiring that all emissions are produced above the photosphere of GRB 090926A, we compute the bulk Lorentz factor of the outflow, Γ. The latter decreases from 230 during the spike to 100 at the end of the prompt emission. Assuming, instead, that the spectral break reflects the natural curvature of the inverse Compton spectrum, lower limits corresponding to larger values of Γ are also derived. Combined with the extreme temporal variability of GRB 090926A, these Lorentz factors lead to emission radii R ∼ 10 14 cm, which are consistent with an internal origin of both the keV−MeV and GeV prompt emissions.

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“…Our methodology is analogous to that of Ackermann et al (2014), who recently applied the DCF to cross-correlating the keV and MeV−GeV light curves of the bright Fermi-LAT-detected GRB 130427A. A similar approach was followed by Del Monte et al (2011).…”

Section: Introductionmentioning

confidence: 99%

Time delays betweenFermi-LAT and GBM light curves of gamma-ray bursts

Castignani

Guetta²,

Pian³

et al. 2014

A&A

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Aims. Most gamma-ray bursts (GRBs) detected by the Fermi Gamma-ray Space Telescope exhibit a delay of up to about 10 seconds between the trigger time of the hard X-ray signal as measured by the Fermi Gamma-ray Burst Monitor (GBM) and the onset of the MeV−GeV counterpart detected by the Fermi Large Area Telescope (LAT). This delay may hint at important physics, whether it is due to the intrinsic variability of the inner engine or related to quantum dispersion effects in the velocity of light propagation from the sources to the observer. Therefore, it is critical to have a proper assessment of how these time delays affect the overall properties of the light curves. Methods. We cross-correlated the 5 brightest GRBs of the 1st Fermi-LAT Catalog by means of the continuous correlation function (CCF) and of the discrete correlation function (DCF). The former is suppressed because of the low number counts in the LAT light curves. A maximum in the DCF suggests there is a time lag between the curves, whose value and uncertainty are estimated through a Gaussian fitting of the DCF profile and light curve simulation via a Monte Carlo approach. Results. The cross-correlation of the observed LAT and GBM light curves yields time lags that are mostly similar to those reported in the literature, but they are formally consistent with zero. The cross-correlation of the simulated light curves yields smaller errors on the time lags and more than one time lag for GRBs 090902B and 090926A. For all 5 GRBs, the time lags are significantly different from zero and consistent with those reported in the literature, when only the secondary maxima are considered for those two GRBs. Conclusions. The DCF method proves the presence of (possibly multiple) time lags between the LAT and GBM light curves in a given GRB and underlines the complexity of their time behavior. While this suggests that the delays should be ascribed to intrinsic physical mechanisms, more sensitivity and more statistics are needed to assess whether time lags are universally present in the early GRB emission and which dynamical time scales they trace.

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Fermi-LAT Observations of the Gamma-Ray Burst GRB 130427A

Cited by 282 publications

References 39 publications

GRB 120711A: an intense INTEGRAL burst with long-lasting softγ-ray emission and a powerful optical flash

GRB 120711A: an intense INTEGRAL burst with long-lasting softγ-ray emission and a powerful optical flash

Time evolution of the spectral break in the high-energy extra component of GRB 090926A

Time delays betweenFermi-LAT and GBM light curves of gamma-ray bursts

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