Esclusivismo e universalismo: forme del pensiero ebraico in Italia tra Cinquecento e Settecento

Guetta, Alessandro

doi:10.1484/m.nutrix-eb.4.00086

Cited by 2 publications

(4 citation statements)

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“…Limits on the optical (Roming et al 2006;Yost et al 2007;Klotz 2009), x-ray (O'Brien et al 2006), GeV (Ando et al 2008;Guetta et al 2011;Beniamini et al 2011;Ackermann et al 2012) and TeV (Atkins et al 2005;Albert et al 2006;Aharonian et al 2009) emission during the prompt phase of GRBs, demonstrate that the observed sub-MeV peak carries most of the GRB's energy. The only (unlikely) possibilities that have not been ruled out are either an extremely strong and sharp peak between 10-100eV or a peak at extremely high energies above the TeV range.…”

Section: The Observationsmentioning

confidence: 98%

“…In §3.7 we explore the dependence of the synchrotron model on this choice and look at 4 representative "GRB types". An additional observation that we use is the limit on the total flux observed in the LAT band (30 MeV-300 GeV), which is at most 0.13 of the GBM (8KeV-40MeV) flux (Beniamini et al 2011;Ando et al 2008;Guetta et al 2011;Ackermann et al 2012).…”

Section: The Observationsmentioning

confidence: 99%

“…Second, the emission region cannot be optically thick. Additionally, the LAT band (100 MeV-300 GeV) GeV component is significantly weaker in most GRBs than the sub-MeV peak (Granot et al 2009(Granot et al , 2010Beniamini et al 2011;Guetta et al 2011;Ackermann et al 2012). We combine these three conditions and constrain the possible phase space in which synchrotron can produce the prompt emission.The paper is organized as follows.…”

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confidence: 99%

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Constraints on the Synchrotron Emission Mechanism in Gamma-Ray Bursts

Beniamini

Piran

2013

ApJ

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We reexamine the general synchrotron model for GRBs' prompt emission and determine the regime in the parameter phase space in which it is viable. We characterize a typical GRB pulse in terms of its peak energy, peak flux and duration and use the latest Fermi observations to constrain the high energy part of the spectrum. We solve for the intrinsic parameters at the emission region and find the possible parameter phase space for synchrotron emission. Our approach is general and it does not depend on a specific energy dissipation mechanism. Reasonable synchrotron solutions are found with energy ratios of 10 −4 < B / e < 10, bulk Lorentz factor values of 300 < Γ < 3000, typical electrons' Lorentz factor values of 3 × 10 3 < γ e < 10 5 and emission radii of the order 10 15 cm < R < 10 17 cm. Most remarkable among those are the rather large values of the emission radius and the electron's Lorentz factor. We find that soft (with peak energy less than 100KeV) but luminous (isotropic luminosity of 1.5 × 10 53 ) pulses are inefficient. This may explain the lack of strong soft bursts. In cases when most of the energy is carried out by the kinetic energy of the flow, such as in the internal shocks, the synchrotron solution requires that only a small fraction of the electrons are accelerated to relativistic velocities by the shocks. We show that future observations of very high energy photons from GRBs by CTA, could possibly determine all parameters of the synchrotron model or rule it out altogether. situation concerning the prompt emission is more complicated.We characterize the conditions within the emitting region by six parameters: the co-moving magnetic field strength, B, the number of relativistic emitters, N e , the ratio between the magnetic energy and the internal energy of the electrons, ≡ B / e , the bulk Lorentz factor of the emitting region, Γ, the minimal electrons' Lorentz factor in the source frame, γ m and the ratio between the shell crossing time and the angular timescale, k. We then characterize a single, "typical", GRB pulse, which is the building block of the GRB lightcurve, by three basic quantities: the peak (sub-MeV) frequency, the peak flux and the duration. We compare the first two, the observed peak (sub-MeV) frequency and the peak flux with the predictions of the synchrotron model and we use the observed duration of the pulse to limit the angular time scale (Sari and Piran 1997a). The synchrotron solution is incomplete without a determination of the accompanying synchrotron self-Compton (SSC) emission, which influences the efficiency of the synchrotron emission. Furthermore, the observations of the high energy SSC emission poses additional constraints on the emitting region. We describe, therefore, a self-consistent synchrotron self-Compton solution.Three additional constraints should be taken into account (see also Daigne et al. 2011). First, energy considerations pose a strong lower limit on the efficiency. The energy of the observed sub-MeV flux, is huge and already highly constraining astrophy...

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Section: The Observationsmentioning

confidence: 98%

Section: The Observationsmentioning

confidence: 99%

mentioning

confidence: 99%

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Constraints on the Synchrotron Emission Mechanism in Gamma-Ray Bursts

Beniamini

Piran

2013

ApJ

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“…The first catalog of LAT includes 35 GRBs with gamma ray emission above 100 GeV [44]. Several models have been proposed to explain this high energy emission [20,45,46] including hadronic models [47,48]. The same photonhadron process that produces the charged pions and subsequently the 100 TeV neutrinos, would also generate neutral pions that decay to photons of similar energy.…”

Section: Neutrinos From Gamma-ray-burstsmentioning

confidence: 99%

Neutrinos from gamma ray bursts in the IceCube and ARA era

Guetta

2015

Journal of High Energy Astrophysics

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In this review I discuss the ultra-high energy neutrinos (UHEN) originated from cosmic-ray propagation (GZK neutrinos) and from Gamma Ray Bursts (GRBs), and discuss their detectability in kilometers scale detectors like ARA and IceCube. While GZK neutrinos are expected from cosmic ray interactions on the CMB, the GRB neutrinos depend on the physics inside the sources. GRBs are predicted to emit UHEN in the prompt and in the later 'after-glow' phase. I discuss the constraints on the hadronic component of GRBs derived from the search of four years of IceCube data for a prompt neutrino flux from gamma-ray bursts (GRBs) and more in general I present the results of the search for high-energy neutrinos interacting within the IceCube detector between 2010 and 2013.

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Esclusivismo e universalismo: forme del pensiero ebraico in Italia tra Cinquecento e Settecento

Cited by 2 publications

References 0 publications

Constraints on the Synchrotron Emission Mechanism in Gamma-Ray Bursts

Constraints on the Synchrotron Emission Mechanism in Gamma-Ray Bursts

Neutrinos from gamma ray bursts in the IceCube and ARA era

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