TY - JOUR
T1 - Flares in gamma-ray bursts
T2 - Disc fragmentation and evolution
AU - Dall'Osso, Simone
AU - Perna, Rosalba
AU - Tanaka, Takamitsu L.
AU - Margutti, Raffaella
N1 - Funding Information:
We thank Andrew MacFadyen and Riccardo Ciolfi for valuable discussions, and Bing Zhang and the anonymous referee for useful comments on the manuscript. RP acknowledges support from NASA-Swift under grant NNX15AR48G, and from the NSF under grant AST-1616157.
PY - 2017
Y1 - 2017
N2 - Flaring activity following gamma-ray bursts (GRBs), observed in both long and short GRBs, signals a long-term activity of the central engine. However, its production mechanism has remained elusive. Here, we develop a quantitative model of the idea proposed by Perna et al. of a disc whose outer regions fragment due to the onset of gravitational instability. The self-gravitating clumps migrate through the disc and begin to evolve viscously when tidal and shearing torques break them apart. Our model consists of two ingredients: theoretical bolometric flare light curves whose shape (width, skewness) is largely insensitive to the model parameters, and a spectral correction to match the bandpass of the available observations, that is calibrated using the observed spectra of the flares. This simple model reproduces, with excellent agreement, the empirical statistical properties of the flares as measured by their width-to-arrival time ratio and skewness (ratio between decay and rise time).We present model fits to the observed light curves of two well-monitored flares, GRB 060418 and GRB 060904B. To the best of our knowledge, this is the first quantitative model able to reproduce the flare light curves and explain their global statistical properties.
AB - Flaring activity following gamma-ray bursts (GRBs), observed in both long and short GRBs, signals a long-term activity of the central engine. However, its production mechanism has remained elusive. Here, we develop a quantitative model of the idea proposed by Perna et al. of a disc whose outer regions fragment due to the onset of gravitational instability. The self-gravitating clumps migrate through the disc and begin to evolve viscously when tidal and shearing torques break them apart. Our model consists of two ingredients: theoretical bolometric flare light curves whose shape (width, skewness) is largely insensitive to the model parameters, and a spectral correction to match the bandpass of the available observations, that is calibrated using the observed spectra of the flares. This simple model reproduces, with excellent agreement, the empirical statistical properties of the flares as measured by their width-to-arrival time ratio and skewness (ratio between decay and rise time).We present model fits to the observed light curves of two well-monitored flares, GRB 060418 and GRB 060904B. To the best of our knowledge, this is the first quantitative model able to reproduce the flare light curves and explain their global statistical properties.
KW - Accretion
KW - Accretion discs
KW - Black hole physics
KW - X-rays: general
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U2 - 10.1093/mnras/stw2695
DO - 10.1093/mnras/stw2695
M3 - Article
AN - SCOPUS:85014873478
VL - 464
SP - 4399
EP - 4407
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
SN - 0035-8711
IS - 4
ER -