Gamma-Ray Bursts in the<i>Swift</i>Era

Gehrels, N.; Ramírez-Ruiz, E.; Fox, D. B.

doi:10.1146/annurev.astro.46.060407.145147

Cited by 587 publications

(491 citation statements)

References 362 publications

(421 reference statements)

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“…Such criteria usually include a bright optical or X-ray counterpart, its close proximity to the Milky Way, or the suspicion of the GRB being an optically dark burst (van der Horst et al 2009. Additionally, while a vast quantity of early-time (within minutes of the burst) optical and X-ray data on GRBs have been collected (see Gehrels et al 2009, and references therein), once again, the rarity of radio telescopes has led to fewer experiments designed to obtain similar early-time observations at radio wavelengths. We clearly require a programme capable of targeting the early-time radio properties of GRBs (< 1 day post-burst), which are specifically sensitive to the reverse-shock contributions to the radio afterglow.…”

Section: Introductionmentioning

confidence: 99%

The Arcminute Microkelvin Imager catalogue of gamma-ray burst afterglows at 15.7 GHz

Anderson

Staley

Horst

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We present the Arcminute Microkelvin Imager (AMI) Large Array catalogue of 139 gamma-ray bursts (GRBs). AMI observes at a central frequency of 15.7 GHz and is equipped with a fully automated rapid-response mode, which enables the telescope to respond to highenergy transients detected by Swift. On receiving a transient alert, AMI can be on-target within two minutes, scheduling later start times if the source is below the horizon. Further AMI observations are manually scheduled for several days following the trigger. The AMI GRB programme probes the early-time (< 1 day) radio properties of GRBs, and has obtained some of the earliest radio detections (GRB 130427A at 0.36 and GRB 130907A at 0.51 days post-burst). As all Swift GRBs visible to AMI are observed, this catalogue provides the first representative sample of GRB radio properties, unbiased by multi-wavelength selection criteria. We report the detection of six GRB radio afterglows that were not previously detected by other radio telescopes, increasing the rate of radio detections by 50% over an 18-month period. The AMI catalogue implies a Swift GRB radio detection rate of 15%, down to ∼ 0.2 mJy/beam. However, scaling this by the fraction of GRBs AMI would have detected in the Chandra & Frail sample (all radio-observed GRBs between 1997 − 2011), it is possible ∼ 44 − 56% of Swift GRBs are radio bright, down to ∼ 0.1 − 0.15 mJy/beam. This increase from the Chandra & Frail rate (∼ 30%) is likely due to the AMI rapid-response mode, which allows observations to begin while the reverse-shock is contributing to the radio afterglow.

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Section: Introductionmentioning

confidence: 99%

The Arcminute Microkelvin Imager catalogue of gamma-ray burst afterglows at 15.7 GHz

Anderson

Staley

Horst

et al. 2017

Monthly Notices of the Royal Astronomical Society

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“…The crucial point in that scenario was that "long" GRBs are intrinsically connected with supernovae (SN) events. "Short" GRBs were instead assumed to originate in coalescing neutron star binaries (see e.g., Gehrels et al 2009, and references therein). The first anomaly of this classification was already present in BATSE data, but was identified only years later by Norris & Bonnell (2006).…”

Section: Introductionmentioning

confidence: 99%

GRB 071227: an additional case of adisguisedshort burst

Caito¹,

Amati

Bernardini

et al. 2010

A&A

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Context. Observations of gamma-ray bursts (GRBs) have shown an hybridization between the two classes of long and short bursts. In the context of the fireshell model, the GRB light curves are formed by two different components: the proper GRB (P-GRB) and the extended afterglow. Their relative intensity is linked to the fireshell baryon loading B. The GRBs with P-GRB predominance are the short ones, the remainders are long. A new family of disguised short bursts has been identified: long bursts with a protracted low instantaneous luminosity due to a low density CircumBurst Medium (CBM). In the 15-150 keV energy band GRB 071227 exhibits a short duration (about 1.8 s) spike-like emission followed by a very soft extended tail up to one hundred seconds after the trigger. It is a faint (E iso = 5.8 × 10 50 ) nearby GRB (z = 0.383) that does not have an associated type Ib/c bright supernova (SN). For these reasons, GRB 071227 has been classified as a short burst not fulfilling the Amati relation holding for long burst. Aims. We check the classification of GRB 071227 provided by the fireshell model. In particular, we test whether this burst is another example of a disguised short burst, after GRB 970228 and GRB 060614, and, for this reason, whether it fulfills the Amati relation. Methods. We simulate GRB 071227 light curves in the Swift BAT 15-50 keV bandpass and in the XRT (0.3-10 keV) energy band within the fireshell model. Results. We perform simulations of the tail in the 15-50 keV bandpass, as well as of the first part of the X-ray afterglow. This infers that: E e ± tot = 5.04 × 10 51 erg, B = 2.0 × 10 −4 , E P−GRB /E aft ∼ 0.25, and n cbm = 3.33 particles cm −3 . These values are consistent with those of "long duration" GRBs. We interpret the observed energy of the first hard emission by identifying it with the P-GRB emission. The remaining long soft tail indeed fulfills the Amati relation. Conclusions. Previously classified as a short burst, GRB 071227 on the basis of our analysis performed in the context of the fireshell scenario represents another example of a disguised short burst, after GRB 970228 and GRB 060614. Further confirmation of this result is that the soft tail of GRB 071227 fulfills the Amati relation.

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“…This is a known relativistic effect and is caused because the particles that emit it propagate at close to the speed of light and form a jet, thus, focussing the radiation along a tight beam. Estimates indicate that particles propagate at ultrarelativistic speeds, at more than 0.9999 c, where c is the speed of light (Gehrels, Ramírez-Ruiz, & Fox, 2009). …”

Section: ■ ■ Observational Evidence: Galactic Nucleimentioning

confidence: 99%

Interstellar travel guide: Chronicles of a violent universe

Perucho

Font

2016

Mètode

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In contrast to observations from our local viewpoint, the universe is extremely violent. Explosions of massive stars, X-ray and gamma-ray binary stars, and active galaxies are related to the presence of compact objects such as neutron stars or black holes. Processes such as matter accretion or the formation and release of relativistic plasma jets are responsible for the generation of large amounts of high-energy radiation, caused by the acceleration of elementary particles, and have a significant impact in their surroundings. Moreover, they are related to the generation of gravitational waves: vibrations in spacetime produced by the acceleration of compact massive objects that produce strong curvatures. These systems are studied within the framework of the general and special relativity theories. In this article, we summarise several of the most well-known astrophysical scenarios, and offer a brief description of what we currently know about them.

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Gamma-Ray Bursts in theSwiftEra

Cited by 587 publications

References 362 publications

The Arcminute Microkelvin Imager catalogue of gamma-ray burst afterglows at 15.7 GHz

The Arcminute Microkelvin Imager catalogue of gamma-ray burst afterglows at 15.7 GHz

GRB 071227: an additional case of adisguisedshort burst

Interstellar travel guide: Chronicles of a violent universe

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