<i>Swift</i>Observations of GRB 070110: An Extraordinary X‐Ray Afterglow Powered by the Central Engine

Troja, E.; Cusumano, G.; O’Brien, P. T.; Zhang, B.; Sbarufatti, B.; Mangano, V.; Willingale, R.; Chincarini, G.; Osborne, J. P.; Marshall, F. E.; Burrows, D. N.; Campana, S.; Gehrels, N.; Guidorzi, C.; Krimm, H. A.; Parola, V. La; Liang, En‐Wei; Mineo, T.; Moretti, A.; Page, K. L.; Romano, P.; Tagliaferri, G.; Zhang, Bingbing; Page, M. J.; Schady, P.

doi:10.1086/519450

Cited by 308 publications

(378 citation statements)

References 62 publications

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“…In the case of a rapidly spinning proto-neutron star, late-time energy injection through electromagnetic dipole radiation has long been suggested as a possible source of achromatic afterglow bumps (Dai & Lu 1998;Zhang & Mészáros 2001;Troja et al 2007;Lyons et al 2010). Alternatively, for black hole systems, changes in the structure of the accretion-disk system could drive an unsteady outflow at late times (Lazzati et al 2008).…”

Section: Discussionmentioning

confidence: 99%

THE COLLIMATION AND ENERGETICS OF THE BRIGHTESTSWIFTGAMMA-RAY BURSTS

Cenko

Frail

Harrison

et al. 2010

ApJ

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128

127

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Long-duration gamma-ray bursts (GRBs) are widely believed to be highly collimated explosions (bipolar conical outflows with half-opening angle θ ≈ 1 • -10 • ). As a result of this beaming factor, the true energy release from a GRB is usually several orders of magnitude smaller than the observed isotropic value. Measuring this opening angle, typically inferred from an achromatic steepening in the afterglow light curve (a "jet" break), has proven exceedingly difficult in the Swift era. Here, we undertake a study of five of the brightest (in terms of the isotropic prompt γ -ray energy release, E γ,iso ) GRBs in the Swift era to search for jet breaks and hence constrain the collimation-corrected energy release. We present multi-wavelength (radio through X-ray) observations of GRBs 050820A, 060418, and 080319B, and construct afterglow models to extract the opening angle and beaming-corrected energy release for all three events. Together with results from previous analyses of GRBs 050904 and 070125, we find evidence for an achromatic jet break in all five events, strongly supporting the canonical picture of GRBs as collimated explosions. The most natural explanation for the lack of observed jet breaks from most Swift GRBs is therefore selection effects. However, the opening angles for the events in our sample are larger than would be expected if all GRBs had a canonical energy release of ∼10 51 erg. The total energy release we measure for the "hyper-energetic" (E tot 10 52 erg) events in our sample is large enough to start challenging models with a magnetar as the compact central remnant.

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Section: Discussionmentioning

confidence: 99%

THE COLLIMATION AND ENERGETICS OF THE BRIGHTESTSWIFTGAMMA-RAY BURSTS

Cenko

Frail

Harrison

et al. 2010

ApJ

Self Cite

128

127

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“…Swift/XRT began observing 143 s after the BAT trigger and found a faint fading X-ray source inside the BAT error circle (Schady et al 2006). The 0.3-10 keV light curve showed a broken power-law decay (Troja et al 2006a). No afterglow candidate was found with UVOT down to 18.5 mag (white light) in the prompt images at t 0 + 140 s (Schady et al 2006).…”

Section: Grb 061006mentioning

confidence: 98%

The optical afterglows and host galaxies of three short/hard gamma-ray bursts

D’Avanzo¹,

Malesani

Covino³

et al. 2009

A&A

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Context. Our knowledge of short gamma-ray bursts (GRBs) has significatively improved in the Swift era. Rapid multiband observations from the largest ground-based observatories led to the discovery of the optical afterglows and host galaxies of these events. In spite of these advancements, the number of short GRBs with secure detections in the optical is still fairly small. Short GRBs are commonly thought to originate from the merging of double compact object binaries but direct evidence for this scenario is still missing. Aims. Optical observations of short GRBs allow us to measure redshifts, firmly identify host galaxies, characterize their properties, and accurately localize GRBs within them. Multiwavelength observations of GRB afterglows provide useful information on the emission mechanisms at work. These are all key issues that allow one to discriminate among different models of these elusive events. Methods. We carried out photometric observations of the short/hard GRB 051227, GRB 061006, and GRB 071227 with the ESO-VLT starting from several hours after the explosion down to the host galaxy level several days later. For GRB 061006 and GRB 071227 we also obtained spectroscopic observations of the host galaxy. We compared the results obtained from our optical observations with the available X-ray data of these bursts. Results. For all the three above bursts, we discovered optical afterglows and firmly identified their host galaxies. About half a day after the burst, the optical afterglows of GRB 051227 and GRB 061006 present a decay significatly steeper than in the X-rays. In the case of GRB 051227, the optical decay is so steep that it likely indicates different emission mechanisms in the two wavelength ranges. The three hosts are blue star forming galaxies at moderate redshifts and with metallicities comparable to the Solar one. The projected offsets of the optical afterglows from their host galaxy center span a wide range, but all afterglows lie within the light of their hosts and present evidence for local absorption in their X-ray spectra. We discuss our findings in light of the current models of short GRB progenitors.

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“…So far, there are two more candidates GRB 060607A [18] and GRB 070110 [26]. Both events are distinguished by a very sharp X-ray drop in the afterglow phase, which is inconsistent with the fireball afterglow interpretation [15,26]. This is in particular the case for GRB 070110 because the optical data simultaneous with the X-ray drop does not steepen at all.…”

Section: Possible Candidates Of Central Engine Afterglowmentioning

confidence: 99%

Central engine afterglow of Gamma-ray Bursts

Fan¹,

Piran²,

Wei³

2008

AIP Conference Proceedings

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Abstract. Before 2004, nearly all GRB afterglow data could be understood in the context of the external shocks model. This situation has changed in the past two years, when it became clear that some afterglow components should be attributed to the activity of the central engine; i.e., the central engine afterglow. We review here the afterglow emission that is directly related to the GRB central engine. Such an interpretation proposed by Katz, Piran & Sari, peculiar in pre-Swift era, has become generally accepted now.Keywords: Gamma-ray: bursts-radiation mechanisms: nonthermal PACS: 98.70.Rz TWO KINDS OF GRB AFTERGLOWSIn the context of standard fireball model of Gamma-ray Bursts (GRBs), the prompt γ−ray emission is powered by internal shocks and the afterglow emission arises due to external shocks (see [21] for a review). In the pre-Swift era, most of the afterglow data was collected hours after the prompt γ−ray emission. These data was found to be consistent with the external forward shock model, though at times energy injection, a wind medium profile, or a structured/patchy jet were needed. We call the emission relevant to the external shocks generated by the GRB remnant as the "fireball afterglow" or "afterglow". An alternative possibility for the production of the afterglow is a continued activity of the central engine (i.e., the central engine afterglow) via either the "internal shocks" or "magnetic dissipation". This idea has been put forward by Katz, Piran & Sari already in 1998, shortly after the discovery of the afterglow of GRB 970228. However, the agreement of the predictions of the external shock afterglow model [24] with most subsequent multi-wavelength afterglows observation strongly disfavors the central engine afterglow interpretation.One disadvantage of the central engine afterglow model is its lack of predictive power. The fireball afterglow model, instead, has predicted smooth light curves and in particular the intrinsic relation between the flux in different bands (e.g., [24]) as well as between the spectral slops and the temporal decay. In 2003, it was already clear that in the case of a fireball afterglow, the variability timescale of the emission δt divided by the occurrence time t has to be in order of 1 or larger [19]. A highly relevant constraint is that the decline of the fireball afterglow emission can not be steeper than t −(2+β ) , (where β is the spectral index) unless the edge of the GRB ejecta is visible. This is because the GRB outflow is curving and emission from high latitude (relative to the observer) will reach us at later

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SwiftObservations of GRB 070110: An Extraordinary X‐Ray Afterglow Powered by the Central Engine

Cited by 308 publications

References 62 publications

THE COLLIMATION AND ENERGETICS OF THE BRIGHTESTSWIFTGAMMA-RAY BURSTS

THE COLLIMATION AND ENERGETICS OF THE BRIGHTESTSWIFTGAMMA-RAY BURSTS

The optical afterglows and host galaxies of three short/hard gamma-ray bursts

Central engine afterglow of Gamma-ray Bursts

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