GRB 090926A AND BRIGHT LATE-TIME FERMI LARGE AREA TELESCOPE GAMMA-RAY BURST AFTERGLOWS

Journal Article · Tue Jul 20 00:00:00 EDT 2010 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/718/1/L14· OSTI ID:21451031

Swenson, C A; Roming, P W. A.; Vetere, L; Kennea, J A ^[1]; Maxham, A; Zhang, B B; Zhang, B ^[2]; Schady, P ^[3]; Holland, S T ^[4]; Kuin, N P. M.; Oates, S R; De Pasquale, M ^[5]

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1. Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States)
2. University of Nevada, Las Vegas, Box 454002, 4505 Maryland Parkway, Las Vegas, NV 89154 (United States)
3. Max-Planck-Institut fuer extraterrestrische Physik, Garching (Germany)
4. Universities Space Research Association, 10227 Wincopin Circle, Suite 500, Columbia, MD 21044 (United States)
5. The UCL Mullard Space Science Laboratory, Holmbury St Mary, Surrey, RH5 6NT (United Kingdom)

GRB 090926A was detected by both the Gamma-ray Burst Monitor and Large Area Telescope (LAT) instruments on board the Fermi Gamma-ray Space Telescope. Swift follow-up observations began {approx}13 hr after the initial trigger. The optical afterglow was detected for nearly 23 days post trigger, placing it in the long-lived category. The afterglow is of particular interest due to its brightness at late times, as well as the presence of optical flares at T0+10{sup 5} s and later, which may indicate late-time central engine activity. The LAT has detected a total of 16 gamma-ray bursts; nine of these bursts, including GRB 090926A, also have been observed by Swift. Of the nine Swift-observed LAT bursts, six were detected by UVOT, with five of the bursts having bright, long-lived optical afterglows. In comparison, Swift has been operating for five years and has detected nearly 500 bursts, but has only seen {approx}30% of bursts with optical afterglows that live longer than 10{sup 5} s. We have calculated the predicted gamma-ray fluence, as would have been seen by the Burst Alert Telescope (BAT) on board Swift, of the LAT bursts to determine whether this high percentage of long-lived optical afterglows is unique, when compared to BAT-triggered bursts. We find that, with the exception of the short burst GRB 090510A, the predicted BAT fluences indicate that the LAT bursts are more energetic than 88% of all Swift bursts and also have brighter than average X-ray and optical afterglows.

• OSTI ID: 21451031
• Journal Information: Astrophysical Journal Letters, Vol. 718, Issue 1; Other Information: DOI: 10.1088/2041-8205/718/1/L14; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
AFTERGLOW
BRIGHTNESS
COSMIC GAMMA BURSTS
GAMMA RADIATION
SHOCK WAVES
TELESCOPES
X RADIATION
COSMIC RADIATION
ELECTROMAGNETIC RADIATION
IONIZING RADIATIONS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
PRIMARY COSMIC RADIATION
RADIATIONS