Gamma-Ray Burst Afterglows

Paradijs, J. van; Kouveliotou, C.; Wijers, R. A. M. J.

doi:10.1146/annurev.astro.38.1.379

Cited by 322 publications

(260 citation statements)

References 192 publications

(172 reference statements)

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“…The parameter m(t) in Equation 4 has a magnitude dependent on the total number of fissions and a known time dependence. The expected GRB afterglow energy distribution is approximated by  ≈ -1 (Paradijs et al 2000) which again is in very nice agreement with the spectral shape of the delayed gamma photon distribution of a fission criticality event given in Equation (4).…”

Section: Grb Energy Spectrasupporting

confidence: 80%

Nuclear criticality as a contributor to gamma ray burst events

Hayes¹

2013

Astrophys Space Sci

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-Most gamma ray bursts are able to be explained using supernovae related phenomenon. Some measured results still lack compelling explanations and a contributory cause from nuclear criticality is proposed. This is shown to have general properties consistent with various known gamma ray burst properties. The galactic origin of fast rise exponential decay gamma ray bursts is considered a strong candidate for these types of events. BackgroundThe Oklo uranium mine in South Africa is a place where the natural abundance of U235 was found to be consistently less than the 0.72% found everywhere else on the planet (with the remainder of the uranium being almost entirely U238). It was not until the excess isotopic distribution from the stable fission product decay nuclides was found that it was realized this was an ancient natural nuclear reactor (Cowan 1976). Because the half life of U235 is almost an order of magnitude smaller than that of U238, the ratio of U235 to U238 increases in reverse time. By going back far enough in time, the abundance of the two nuclides would become comparable. With sufficiently enriched uranium in the soil, addition of moisture from rain would then provide the necessary moderation for the earth to sustain a natural nuclear chain reaction until the heat would drive away the water and return the system to a subcritical state. This process is believed to have occurred over a billion years ago in central Africa (Fujii et al. 2000).If the Oklo reactor occurred naturally as a result of uranium created in supernovae (SN) events, it is not incredible to think that it could occur prior to accumulation into planetary form from other SN events. In other words, just after the SN creation of the uranium and transuranic isotopes, most of the already radioactive elements created will quickly decay into stable atoms leaving these fissile and fissionable isotopes close to their original abundance. Even if a large fraction of the Pu239 (which is fissile with a moderately long half life of just over 24 ka) were to decay away, there would still be almost the initial amount of U233 (which is fissile with a moderately long half life of just under 0.2 ma) with only a negligible fraction of the U235 having decayed away. If a gravitational accumulation of the SN excreta were to occur within some few years, a longer list of potential fissile isotopes could be present in the material including Pu241, Am243, Cm243, Cm245, Cm247, etc while the majority of the radioactive elements would still have decayed into stable isotopes. This presents a dynamic reactivity dependency in terms of the fissile nuclides generated which would be strongly dependent on the initial isotopic distribution source term.The model presented here has the potential to explain some of the highly varied nature of a portion of measured gamma ray bursts (GRBs). These include the random nature of the events in terms of their parametric values and ranges. Specifically many measured values of energy and time distributions, pulsing, and afterglows ...

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Section: Grb Energy Spectrasupporting

confidence: 80%

Nuclear criticality as a contributor to gamma ray burst events

Hayes¹

2013

Astrophys Space Sci

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“…Since then, several X-ray, optical, and radio counterparts of GRBs have been detected. These multiwavelength afterglow observations can be explained reasonably well by simple Ðreball models (for recent reviews see Piran 1999 ;van Paradijs, Kouveliotou, & Wijers 2000). GRB distance determinations are crucial in the e †ort to establish the physical nature of their progenitor(s).…”

Section: Introductionmentioning

confidence: 68%

VLT Spectroscopy of GRB 990510 and GRB 990712: Probing the Faint and Bright Ends of the Gamma‐Ray Burst Host Galaxy Population

Vreeswijk

Fruchter

Kaper

et al. 2001

ApJ

108

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We present time-resolved optical spectroscopy of the afterglows of the gamma-ray bursts GRB 990510 and GRB 990712. Through the identiÐcation of several absorption lines in the Ðrst-epoch GRB 990510 spectrum, we determine the redshift for this burst at z º 1.619. No clear emission lines are detected. The strength of the Mg I feature is indicative of a dense environment, most likely the host galaxy of GRB 990510. Although the host is extremely faint the GRB afterglow allows us to probe its inter-(V Z 28), stellar medium andÈin principleÈto measure its metallicity. The optical spectrum of GRB 990712 (whose host galaxy is the brightest of the known GRB hosts at cosmological redshifts) shows clear features both in emission and absorption, at a redshift of z \ 0.4331^0.0004. On the basis of several line emission diagnostic diagrams, we conclude that the host galaxy of GRB 990712 is most likely an H II galaxy. We derive an unreddened [O II] star formation rate of 2.7^0.8 yr~1. Correcting for the M _ measured extinction intrinsic to the host galaxy this value increases to yr~1.width, compared to that of Ðeld galaxies at z ¹ 1, also suggests that the host of GRB 990712 is vigorously forming stars. We employ the oxygen and Hb emission-line intensities to estimate the global oxygen abundance for the host of GRB 990712 : log (O/H) \ [3.7^0.4, which is slightly below the lowest metallicity one Ðnds in nearby spiral galaxies. For both GRBs we study the time evolution of the absorption lines, whose equivalent width might be expected to change with time if the burst resides in a dense compact medium. We Ðnd no evidence for a signiÐcant change in the Mg II width.

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“…Studies of afterglows confirmed the synchrotron shock model (e.g., Wijers, Rees, & Mészáros 1997), and their physics now seems to be reasonably well understood (see, e.g., Mész-áros 2002, Waxman 2003, andreferences therein). Other recent reviews include Kulkarni et al (2000), van Paradijs, Kouveliotou, & Wijers (2000), Hurley, Sari, & Djorgovski (2003), and Djorgovski et al (2002Djorgovski et al ( , 2003.…”

Section: Introductionmentioning

confidence: 99%

The Redshift and the Host Galaxy of GRB 980613: A Gamma-Ray Burst from a Merger-induced Starburst?

Djorgovski

Bloom

Kulkarni

2003

ApJ

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We present the optical and near-IR identification and spectroscopy of the host galaxy of gamma-ray burst GRB 980613. The burst was apparently associated with the optically (rest-frame UV) brightest component of an apparent system of at least five galaxies or galaxy fragments, at least two of which are at a redshift of . The z p 1.0969 component we identify as the host galaxy shows a moderately high unobscured star formation rate, SFR ∼ 5 M , yr , but a high SFR per unit mass, indicative of a starburst. The image components show a broad range of Ϫ1 colors, with two of them being very red, possibly due to dust. The overall morphology of the system (RϪK) can be naturally interpreted as a strong tidal interaction of two or more galaxies, at a redshift where such events were much more common than now. Given the well-established causal link between galaxy mergers and starbursts, we propose that this is a strong case for a GRB originating from a merger-induced starburst system. This supports the proposed link between GRBs and massive star formation.

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Gamma-Ray Burst Afterglows

Cited by 322 publications

References 192 publications

Nuclear criticality as a contributor to gamma ray burst events

Nuclear criticality as a contributor to gamma ray burst events

VLT Spectroscopy of GRB 990510 and GRB 990712: Probing the Faint and Bright Ends of the Gamma‐Ray Burst Host Galaxy Population

The Redshift and the Host Galaxy of GRB 980613: A Gamma-Ray Burst from a Merger-induced Starburst?

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