|
| | | | |
| | | |
| Stat |
Members: 3665
Articles: 2'599'751
Articles rated: 2609
20 January 2025 |
|
| | | | |
|
Article overview
| |
|
|
A Comprehensive Study of Short Bursts from SGR 1806-20 and SGR 1900+14 Detected by HETE-2 | | Yujin E. Nakagawa
; Atsumasa Yoshida
; Kevin Hurley
; Jean-Luc Atteia
; Miki Maetou
; Toru Tamagawa
; Motoko Suzuki
; Tohru Yamazaki
; Kaoru Tanaka
; Nobuyuki Kawai
; Yuji Shirasaki
; Alexandre Pelangeon
; Masaru Matsuoka
; Roland Vanderspek
; Geoff B. Crew
; Joel S. Villasenor
; Rie Sato
; Satoshi Sugita
; Jun’ichi Kotoku
; Makoto Arimoto
; Graziella Pizzichini
; John P. Doty
; George R. Ricker
; | | Date: |
24 Jan 2007 | | Abstract: | We present the results of temporal and spectral studies of the short burst (less than a few hundred milliseconds) from the soft gamma repeaters (SGRs) 1806-20 and 1900+14 using the HETE-2 samples. In five years from 2001 to 2005, HETE-2 detected 50 bursts which were localized to SGR 1806-20 and 5 bursts which were localized to SGR 1900+14. Especially SGR 1806-20 was active in 2004, and HETE-2 localized 33 bursts in that year. The cumulative number-intensity distribution of SGR 1806-20 in 2004 is well described by a power law model with an index of -1.1+/-0.6. It is consistent with previous studies but burst data taken in other years clearly give a steeper distribution. This may suggest that more energetic bursts could occur more frequently in periods of greater activity. A power law cumulative number-intensity distribution is also known for earthquakes and solar flares. It may imply analogous triggering mechanisms. Although spectral evolution during bursts with a time scale of > 20 ms is not common in the HETE-2 sample, spectral softening due to the very rapid (< a few milliseconds) energy reinjection and cooling may not be excluded. The spectra of all short bursts are well reproduced by a two blackbody function (2BB) with temperatures ~ 4 and ~ 11 keV. From the timing analysis of the SGR 1806-20 data, a time lag of 2.1+/-0.4 ms is found between the 30-100 keV and 2-10 keV radiation bands. This may imply (1) a very rapid spectral softening and energy reinjection, (2) diffused (elongated) emission plasma along the magnetic field lines in pseudo equilibrium with multi-temperatures, or (3) a separate (located at < 700 km) emission region of softer component (say, ~ 4 keV) which could be reprocessed X-rays by higher energy (> 11 keV) photons from an emission region near the stellar surface. | | Source: | arXiv, astro-ph/0701701 | | Services: | Forum | Review | PDF | Favorites | |
|
|
No review found.
Did you like this article?
Note: answers to reviews or questions about the article must be posted in the forum section.
Authors are not allowed to review their own article. They can use the forum section.
|
| |
|
|
|
REGISTER