Giant X-Ray Bump in GRB 121027a: Evidence for Fall-Back Disk Accretion

Wu, Xue-Feng; Hou, Shu-Jin; Lei, Wei‐Hua

doi:10.1088/2041-8205/767/2/l36

Cited by 87 publications

(104 citation statements)

References 43 publications

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“…The temporal analysis and spectral property suggest that the X-ray flare is from a distinct emission mechanism, since the temporal behavior of flares is quite similar to the prompt emission pulses, whereas different from the other four components in the canonical light-curves. Thus, X-ray flares may have a common physical origin as the prompt pulses (Burrows et al 2005b;Falcone et al 2006Falcone et al , 2007Liang et al 2006;Nousek et al 2006;Zhang et al 2006;Chincarini et al 2007Chincarini et al , 2010Wu et al 2013;Hou et al 2014a;Yi et al 2015), and are probably related to the late time activity of the central engine (Romano et al 2006;Bernardini et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Central Engine of Late-Time X-Ray Flares With Internal Origin

Hou

et al. 2016

ApJ

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This work focuses on a sample of seven extremely late-time X-ray flares with peak time t p > 10 4 s, among which two flares can be confirmed as the late-time activity of central engine. The main purpose is to investigate the mechanism of such late-time flares based on the internal origin assumption. In the hyper-accreting black hole (BH) scenario, we study the possibility of two well-known mechanisms as the central engine to power such X-ray flares, i.e., the neutrino-antineutrino annihilation and the Blandford-Znajek (BZ) process. Our results show that the annihilation luminosity is far below the observational data. Thus, the annihilation mechanism cannot account for such late-time flares. For the BZ process, if the role of outflows is taken into consideration, the inflow mass rate near the horizon will be quite low such that the magnetic field will probably be too weak to power the observed X-ray flares. We therefore argue that, for the late-time flares with internal origin, the central engine is unlikely to be associated with BHs. On the contrary, a fast rotating neutron star with strong bipolar magnetic fields may be responsible for such flares.

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Section: Introductionmentioning

confidence: 99%

Central Engine of Late-Time X-Ray Flares With Internal Origin

Hou

et al. 2016

ApJ

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“…The neutrino annihilation luminosity of such NDAFs may be powerful enough to account for most of GRBs including the ultra-LGRBs (ULGRBs), and viscously unstable emerges in the inner region of the disk, which may be interpreted the origin of GRBs variabilities. Wu et al (2013) presented that a BZ jet launched from the BH hyperaccretion system in the fall-back framework (Kumar et al 2008a,b) can explain the giant X-ray bump in GRB 121027A. Gao et al (2016) investigated that the BZ jet and Blandford-Payne (BP, Blandford & Payne 1982) outflow can interpret the ULGRB GRB 111209A and its associated SN 2011kl.…”

Section: Magnetized Bh-ndafsmentioning

confidence: 99%

“…where J = a * GM 2 /c is the angular momentum of the BH, e ms and l ms are the specific energy and angular momentum corresponding to the marginally stable orbit radius r ms of the disk, i.e., (e.g., Novikov & Thorne 1973;Wu et al 2013;Hou et al 2014b)…”

Section: Evolution Of Ndafs For Grbsmentioning

confidence: 99%

Neutrino-dominated accretion flows as the central engine of gamma-ray bursts

Liu

Zhang

2017

New Astronomy Reviews

120

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Neutrino-dominated accretion flows (NDAFs) around rotating stellar-mass black holes (BHs) are plausible candidates for the central engines of gamma-ray bursts (GRBs). NDAFs are hyperaccretion disks with accretion rates in the range of around 0.001-10 M ⊙ s −1 , which have high density and temperature and therefore are extremely optically thick and geometrically slim or even thick. We review the theoretical progresses in studying the properties of NDAFs as well as their applications to the GRB phenomenology. The topics include: the steady radial and vertical structure of NDAFs and the implications for calculating neutrino luminosity and annihilation luminosity, jet power due to neutrino-antineutrino annihilation and Blandford-Znajek mechanism and their dependences on parameters such as BH mass, spin, and accretion rate, time evolution of NDAFs, effect of magnetic fields, applications of NDAF theories to the GRB phenomenology such as lightcurve variability, extended emission, X-ray flares, kilonovae, etc., as well as probing NDAFs using multi-messenger signals such as MeV neutrinos and gravitational waves.

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“…GRB 070110;Troja et al 2007;Lyons et al 2010;Lü & Zhang 2014;Lü et al 2015;Gao et al 2016a;Li et al 2016;Chen et al 2017), or giant bumps (e.g. GRB 121027A and GRB 111209A; Wu et al 2013;Gao et al 2016b) in X-ray lightcurves. These observations suggest that the GRB central engine is long-lived.…”

Section: Late Central Engine Activitiesmentioning

confidence: 99%

Hyperaccreting Black Hole as Gamma-Ray Burst Central Engine. II. Temporal Evolution of the Central Engine Parameters during the Prompt and Afterglow Phases

Lei

Zhang

et al. 2017

ApJ

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A hyperaccreting stellar-mass black hole has been proposed as the candidate central engine of gamma-ray bursts (GRBs). The rich observations of GRBs by Fermi and Swift make it possible to constrain the central engine model by comparing the model predications against data. This paper is dedicated to studying the temporal evolution of central engine parameters for both prompt emission and afterglow phases. We consider two jet launching mechanisms, i.e., νν annihilations and the Blandford-Znajek (BZ) processe, and obtain analytical solutions to these two models. We then investigate the black hole central engine parameters, such as the jet power, the dimensionless entropy η, and the central engine parameter µ 0 = η(1 + σ 0 ) (where σ 0 is the initial magnetization of the engine) at the base of the jet. The black hole may be spun up by accretion, or spun down by the BZ process, leaving imprints in GRB lightcurves. Usually, a BZ jet is more powerful and is likely responsible for the late time central engine activities. However, an initially non-spinning black hole central engine may first launch a thermal "fireball" via neutrino annihilations, and then launch a Poynting-fluxdominated jet via the BZ process. Multiple flares, giant bumps, and plateaus in GRB afterglows can be well produced as the result of late time accretion onto the black hole.

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Giant X-Ray Bump in GRB 121027a: Evidence for Fall-Back Disk Accretion

Cited by 87 publications

References 43 publications

Central Engine of Late-Time X-Ray Flares With Internal Origin

Central Engine of Late-Time X-Ray Flares With Internal Origin

Neutrino-dominated accretion flows as the central engine of gamma-ray bursts

Hyperaccreting Black Hole as Gamma-Ray Burst Central Engine. II. Temporal Evolution of the Central Engine Parameters during the Prompt and Afterglow Phases

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