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Title: GRB 050911: A black hole-neutron star merger or a naked GRB
Authors: Page, K. L.
King, A. R.
O'Brien, P. T.
Osborne, J. P.
Beardmore, A. P.
Goad, M. R.
Godet, O.
Levan, A. J.
Tanvir, N. R.
Barthelmy, S. D.
Gehrels, N.
Markwardt, C. B.
Sakamoto, T.
Burrows, D. N.
Kennea, J. A.
Campana, S.
Graham, J.
Kaneko, Y.
Reichart, D. E.
First Published: 20-Jan-2006
Publisher: American Astronomical Society, IOP Publishing
Citation: The Astrophysical Journal, 637:L13–L16, 2006 January 20
Abstract: GRB 050911, discovered by the Swift Burst Alert Telescope, was not seen 4.6 hr later by the Swift X-ray Telescope, making it one of the very few X-ray nondetections of a gamma-ray burst (GRB) afterglow at early times. The γ-ray light curve shows at least three peaks, the first two of which (~T[SUBSCRIPT 0] - 0.8 and T[SUBSCRIPT 0] + 0.2 s, where T[SUBSCRIPT 0] is the trigger time) were short, each lasting 0.5 s. This was followed by later emission 10-20 s postburst. The upper limit on the unabsorbed X-ray flux was 1.7 × 10^-14 ergs cm^-2 s^-1 (integrating 46 ks of data taken between September 11 and 18), indicating that the decay must have been rapid. All but one of the long bursts detected by Swift were above this limit at ~4.6 hr, whereas the afterglows of short bursts became undetectable more rapidly. Deep observations with Gemini also revealed no optical afterglow 12 hr after the burst, down to r = 24.0 (5 σ limit). We speculate that GRB 050911 may have been formed through a compact object (black hole-neutron star) merger, with the later outbursts due to a longer disk lifetime linked to a large mass ratio between the merging objects. Alternatively, the burst may have occurred in a low-density environment, leading to a weak, or nonexistent, forward shock—the so-called "naked GRB" model.
DOI Link: 10.1086/500430
ISSN: 2041-8205
eISSN: 2041-8213
Type: Journal Article
Rights: Creative Commons “Attribution Non-Commercial No Derivatives” licence CC BY-NC-ND, further details of which can be found via the following link: Archived with reference to SHERPA/RoMEO and publisher website.
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

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