Fermi/GAMMA-RAY BURST MONITOR OBSERVATIONS OF SGR J0501+4516 BURSTS

Journal Article · Sat Oct 01 00:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/739/2/87; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21587471

Lin, Lin; Shuangnan, Zhang ^[1]; Kouveliotou, Chryssa ^[2]; Baring, Matthew G ^[3]; Van der Horst, Alexander J; Finger, Mark H ^[4]; Guiriec, Sylvain; Preece, Robert; Chaplin, Vandiver; Bhat, Narayan ^[5]; Woods, Peter M ^[6]; Goegues, Ersin; Kaneko, Yuki ^[7]; Scargle, Jeffrey ^[8]; Granot, Jonathan ^[9]; Von Kienlin, Andreas ^[10]; Watts, Anna L; Gehrels, Neil; Harding, Alice ^[11]

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1. National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)
2. Space Science Office, VP62, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States)
3. Department of Physics and Astronomy, Rice University, Houston, TX 77251 (United States)
4. NSSTC, Universities Space Research Association, Huntsville, AL 35805 (United States)
5. CSPAR, University of Alabama in Huntsville, Huntsville, AL 35805 (United States)
6. Corvid Technologies, Huntsville, AL 35806 (United States)
7. Faculty of Engineering and Natural Sciences, Sabanci University, Orhanli- Tuzla, Istanbul 34956 (Turkey)
8. Space Science and Astrobiology Division, NASA/Ames Research Center, Moffett Field, CA 94035-1000 (United States)
9. Centre for Astrophysics Research, University of Hertfordshire, Hatfield, Herts, AL10 9AB (United Kingdom)
10. Max Planck Institute for extraterrestrial Physics, 85748 Garching (Germany)
11. NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

We present our temporal and spectral analyses of 29 bursts from SGR J0501+4516, detected with the gamma-ray burst monitor on board the Fermi Gamma-ray Space Telescope during 13 days of the source's activation in 2008 (August 22- September 3). We find that the T{sub 90} durations of the bursts can be fit with a log-normal distribution with a mean value of {approx}123 ms. We also estimate for the first time event durations of soft gamma repeater (SGR) bursts in photon space (i.e., using their deconvolved spectra) and find that these are very similar to the T{sub 90} values estimated in count space (following a log-normal distribution with a mean value of {approx}124 ms). We fit the time-integrated spectra for each burst and the time-resolved spectra of the five brightest bursts with several models. We find that a single power law with an exponential cutoff model fits all 29 bursts well, while 18 of the events can also be fit with two blackbody functions. We expand on the physical interpretation of these two models and we compare their parameters and discuss their evolution. We show that the time-integrated and time-resolved spectra reveal that E{sub peak} decreases with energy flux (and fluence) to a minimum of {approx}30 keV at F = 8.7 x 10{sup -6} erg cm{sup -2} s{sup -1}, increasing steadily afterward. Two more sources exhibit a similar trend: SGRs J1550-5418 and 1806-20. The isotropic luminosity, L{sub iso}, corresponding to these flux values is roughly similar for all sources (0.4-1.5 x 10{sup 40} erg s{sup -1}).

• OSTI ID: 21587471
• Journal Information: Astrophysical Journal, Vol. 739, Issue 2; Other Information: DOI: 10.1088/0004-637X/739/2/87; Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
COSMIC GAMMA BURSTS
MONITORS
PULSARS
COSMIC RADIATION
COSMIC RADIO SOURCES
IONIZING RADIATIONS
MEASURING INSTRUMENTS
PRIMARY COSMIC RADIATION
RADIATIONS