BATSE Observations of Gamma‐Ray Burst Spectra. IV. Time‐resolved High‐Energy Spectroscopy

Preece, R.; Pendleton, G. N.; Briggs, M. S.; Mallozzi, Robert S.; Pačiesas, W. S.; Band, D. L.; Matteson, J. L.; Meegan, C.

doi:10.1086/305402

Cited by 106 publications

(140 citation statements)

References 30 publications

Supporting

Mentioning

128

Contrasting

Order By: Relevance

“…d Note that the value of is consistent with the spectral slope below c in the fast-cooling mode and the spectral slope below of the high-energy slope, depending on how well the data tolerate curvature (see Fig. 1 in Preece et al 1998). The broken power-law model was therefore used for these six events, resulting in slightly better reduced 2 -values and better constrained values of the fitted high-energy slope.…”

Section: No 2 2002 Extended Power-law Decays In Batse Grbssupporting

confidence: 53%

“…a broken power-law (BPL) model is a better representation of the data (Preece et al 1998). Spectra of X-ray afterglows in the 2-10 keV range observed with BeppoSAX are best fitted with a single power law, with spectral indices that range from À1.5 to À2.3 (Costa 2000).…”

Section: No 2 2002 Extended Power-law Decays In Batse Grbsmentioning

confidence: 99%

“…In six bursts, however, the fitted value of the high-energy slope was unusually steep (dÀ4.0). Preece et al (1998) pointed out that spectral models with curvature can sometimes overestimate the steepness Note.-For most events, the fluence interval is the same interval used in making the temporal fit. Uncertainties in the model parameters are taken from the covariance matrix.…”

Section: No 2 2002 Extended Power-law Decays In Batse Grbsmentioning

confidence: 99%

See 2 more Smart Citations

Extended Power-Law Decays in BATSE Gamma-Ray Bursts: Signatures of External Shocks?

Giblin

Connaughton

Paradijs

et al. 2003

AIP Conference Proceedings

View full text Add to dashboard Cite

The connection between gamma-ray bursts (GRBs) and their afterglows is currently not well understood. Afterglow models of synchrotron emission generated by external shocks in the GRB fireball model predict emission detectable in the gamma-ray regime (e25 keV). In this paper, we present a temporal and spectral analysis of a subset of BATSE GRBs with smooth extended emission tails to search for signatures of the '' early high-energy afterglow,'' i.e., afterglow emission that initially begins in the gamma-ray phase and subsequently evolves into X-ray, UV, optical, and radio emission as the blast wave is decelerated by the ambient medium. From a sample of 40 GRBs we find that the temporal decays are best described with a power law $t rather than an exponential with a mean index h i % À2. Spectral analysis shows that $20% of these events are consistent with fast-cooling synchrotron emission for an adiabatic blast wave, three of which are consistent with the blast-wave evolution of a jet with F $ t Àp . This behavior suggests that in some cases, the emission may originate from a narrow jet, possibly consisting of '' nuggets '' whose angular sizes are less than 1=À, where C is the bulk Lorentz factor.

show abstract

Section: No 2 2002 Extended Power-law Decays In Batse Grbssupporting

confidence: 53%

Section: No 2 2002 Extended Power-law Decays In Batse Grbsmentioning

confidence: 99%

Section: No 2 2002 Extended Power-law Decays In Batse Grbsmentioning

confidence: 99%

See 1 more Smart Citation

Extended Power-Law Decays in BATSE Gamma-Ray Bursts: Signatures of External Shocks?

Giblin

Connaughton

Paradijs

et al. 2003

AIP Conference Proceedings

View full text Add to dashboard Cite

show abstract

“…This figure also shows the hardness ratio as a function of time. A hard-to-soft evolution, which is often observed in GRBs (e.g., Preece et al 1998), is evident. The energy spectra are presented in Figure 2.…”

Section: Observationsmentioning

confidence: 78%

Multiwavelength Studies of the Optically Dark Gamma‐Ray Burst 001025A

Pedersen

Hurley

Hjorth

et al. 2006

ApJ

View full text Add to dashboard Cite

We identify the fading X-ray afterglow of GRB 001025A from XMM-Newton observations obtained 1.9-2.3 days, 2 yr, and 2.5 yr after the burst. The nondetection of an optical counterpart to an upper limit of R ¼ 25:5, 1.20 days after the burst, makes GRB 001025A a ''dark'' burst. Based on the X-ray afterglow spectral properties of GRB 001025A, we argue that some bursts appear optically dark because their afterglow is faint and their cooling frequency is close to the X-ray band. This interpretation is applicable to several of the few other dark bursts where the X-ray spectral index has been measured. The X-ray afterglow flux of GRB 001025A is an order of magnitude lower than for typical longduration gamma-ray bursts. The spectrum of the X-ray afterglow can be fitted with an absorbed synchrotron emission model, an absorbed thermal plasma model, or a combination thereof. For the latter, an extrapolation to optical wavelengths can be reconciled with the R-band upper limit on the afterglow, without invoking any optical circumburst absorption, provided the cooling frequency is close to the X-ray band. Alternatively, if the X-ray afterglow is due to synchrotron emission only, 7 mag of extinction in the observed R-band is required to meet the R-band upper limit, making GRB 001025A much more obscured than bursts with detected optical afterglows. Based on the column density of X-ray-absorbing circumburst matter, an SMC gas-to-dust ratio is insufficient to produce this amount of extinction. The X-ray tail of the prompt emission enters a steep temporal decay excluding that the tail of the prompt emission is the onset of the afterglow. To within the astrometric uncertainty, this afterglow was coincident with an extended object, seen in a deep VLT R-band image, which we identify as the likely host galaxy of GRB 001025A.

show abstract

“…Spectra of GRBs display both a universal break feature at %200 keV (Preece et al 2000) and a wildly variable low-energy spectral index (Crider et al 1997;Preece et al 1998;Ghirlanda, Celotti, & Ghisellini 2002), which have proved difficult to reproduce theoretically: to wit, look at Figure 1 of Mészáros & Rees (2000). In particular, it seems that pure synchrotron emission is incapable of explaining at least some (but not all!…”

Section: Comparison With Other Workmentioning

confidence: 99%

On the Generation of Ultra–High‐Energy Cosmic Rays in Gamma‐Ray Bursts: A Reappraisal

Vietri

Marco

Guetta

2003

ApJ

View full text Add to dashboard Cite

We reexamine critically the arguments raised against the theory that ultra-high-energy cosmic rays (UHECRs) observed at Earth are produced in gamma-ray bursts (GRBs). These include the limitations to the highest energy attainable by protons around the bursts' shocks, the spectral slope at the highest energies, the total energy released in nonthermal particles, and the occurrence of doublets and a triplet in the data reported by the Akeno Giant Air Shower Array (AGASA). We show that, to within the uncertainties in our current knowledge of GRBs, none of these objections is really fatal to the scenario. In particular, we show that the total energy budget of GRBs easily accounts for the energy injection rate necessary to account for UHECRs as observed at Earth. We also compute the expected particle spectrum at Earth, showing that it fits the HiRes and AGASA data to within statistical uncertainties. We consider the existence of multiplets in AGASA data. To this end, we present a Langevin-like treatment for the motion of a charged particle in the intergalactic-medium magnetic field, which allows us to estimate both the average and the rms time delay for particles of given energy; we discuss when particles of identical energies reach the Earth in bunches or spread over the rms time delay, showing that multiplets pose no problem for an explosive model for the sources of UHECRs. We compare our model with a scenario in which the particles are accelerated at internal shocks, underlining the differences and advantages of particle acceleration at external shocks.

show abstract

BATSE Observations of Gamma‐Ray Burst Spectra. IV. Time‐resolved High‐Energy Spectroscopy

Cited by 106 publications

References 30 publications

Extended Power-Law Decays in BATSE Gamma-Ray Bursts: Signatures of External Shocks?

Extended Power-Law Decays in BATSE Gamma-Ray Bursts: Signatures of External Shocks?

Multiwavelength Studies of the Optically Dark Gamma‐Ray Burst 001025A

On the Generation of Ultra–High‐Energy Cosmic Rays in Gamma‐Ray Bursts: A Reappraisal

Contact Info

Product

Resources

About