Статья

<i>Swift</i>UVOT Observations of X‐Ray Flash 050406

P. SchadyDepartment of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802K. O. MasonJ. P. OsborneX-ray and Observational Astronomy Group, Department of Physics and Astronomy, University of Leicester, LE1 7RH, UKM. J. PageThe University College London Mullard Space Science Laboratory, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UKP. W. A. RomingDepartment of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802M. StillNASA Goddard Space Flight Center, Greenbelt, MD 20771Bing ZhangDepartment of Physics, University of Nevada, Las Vegas, NV 89154A. J. BlustinThe University College London Mullard Space Science Laboratory, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UKPatricia T. BoydNASA Goddard Space Flight Center, Greenbelt, MD 20771A. CucchiaraDepartment of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802N. GehrelsNASA Goddard Space Flight Center, Greenbelt, MD 20771C. GronwallDepartment of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802M. De PasqualeThe University College London Mullard Space Science Laboratory, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UKK. L. PageNASA Goddard Space Flight Center, Greenbelt, MD 20771F. E. MarshallNASA Goddard Space Flight Center, Greenbelt, MD 20771K. McGowanThe University College London Mullard Space Science Laboratory, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UKJ. A. NousekDepartment of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802

2006en

ABI

Аннотация

We present Swift-UVOT data on the optical afterglow of the X-ray flash of 2005 April 6 (XRF 050406) from 88s to \sim 10^5s after the initial prompt gamma-ray emission. Our observations in the V, B and U bands are the earliest that have been taken of an XRF optical counterpart. Combining the early -time optical temporal and spectral properties with \gamma- and simultaneous X-ray data taken with the BAT and XRT telescopes on-board Swift, we are able to constrain possible origins of the XRF. The prompt emission had a FRED profile (fast-rise, exponential decay) with a duration of T_90 = 5.7\pm 0.2s, putting it at the short end of the long-burst duration distribution. The absence of photoelectric absorption red-ward of 4000 \AA in the UV/optical spectrum provides a firm upper limit of z\leq 3.1 on the redshift, thus excluding a high redshift as the sole reason for the soft spectrum. The optical light curve is consistent with a power-law decay with slope alpha = -0.75\pm 0.26 (F_{\nu}\propto t^{\alpha}), and a maximum occurring in the first 200s after the initial gamma-ray emission. The softness of the prompt emission is well described by an off-axis structured jet model, which is able to account for the early peak flux and shallow decay observed in the optical and X-ray bands.

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Идентификаторы

DOI: 10.1086/501449

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Цитирований: 3Использованных источников: 0

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