X-ray flare in XRF 050406: Evidence for prolonged engine activity

P. Romano, A. Moretti, P. L. Banat, D. N. Burrows, S. Campana, G. Chincarini, S. Covino, D. Malesani, G. Tagliaferri, A. D. Falcone, M. Capalbi, G. Cusumano, P. Giommi, V. La Parola, V. Mangano, M. Perri, C. Pagani

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations


We present observations of XRF 050406, an X-ray flash with a relatively low fluence (∼ 10-7 erg cm-2 in the 15-350 keV band), a soft spectrum (photon index Γγ = 2.65), no significant flux above ∼ 50 keV and a peak energy Ep < 15 keV. XRF 050406 is the first burst detected by Swift clearly showing a flare in its X-ray light curve. The flare peaks 210 s after the BAT trigger, presents a flux variation δF/F ∼ 6 in a timescale δt/tpeak ≪ 1 and a measured fluence of 1-15% of the prompt one. We argue that the producing mechanism is late internal shocks, which implies that the central engine is still active at 210 s, though with a reduced power with respect to the prompt emission. The X-ray light curve flattens to a more shallow slope with a decay index of ∼ 0.5 after ∼ 4400 s, also supporting continued central engine activity.

Original languageEnglish (US)
Title of host publicationGAMMA-RAY BURSTS IN THE SWIFT ERA
Subtitle of host publicationSixteenth Maryland Astrophysics Conference
Number of pages4
StatePublished - May 19 2006
EventGAMMA-RAY BURSTS IN THE SWIFT ERA: 16th Maryland Astrophysics Conference - Washington, D.C., United States
Duration: Nov 29 2005Dec 2 2005

Publication series

NameAIP Conference Proceedings
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616


OtherGAMMA-RAY BURSTS IN THE SWIFT ERA: 16th Maryland Astrophysics Conference
Country/TerritoryUnited States
CityWashington, D.C.

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy


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