HETE- 2 OBSERVATIONS OF THE EXTREMELY SOFT X-RAY FLASH XRF 020903

1
HETE- 2 OBSERVATIONS OF THE EXTREMELYSOFT X-RAY
FLASH XRF 020903

• Liang Jau-shian
• Institute of Physics, NTHU

2
Introduction The Vela satellites

• The discovery of GRB was published in the year
  1973.

3
IPN (Interplanetary Network)

• 1980s
• Helios 2, Pioneer Venus Orbiter, International
  Sun-Earth Explorer, Venera 11, Venera 12, the
  Earth orbiter Prognoz 7

4
The Compton Gamma-Ray Observatory

• April 1991
• The Burst and Transient Source Experiment (BATSE)
  (10keV MeV)

5
(No Transcript)
6
Observational properties

• GRB light curves

7
Durations
8
Classes of Bursts

• duration/fluence/spectrum
• Long/bright/soft bursts (59)
• Short/faint/hard bursts (23)
• Intermediate (2-5 s)/intermediate/soft busts (18)

9
GRB energy spectra

• Range 1keV-18GeV

10
The Band function
Epeak is the energy of the peak of Spectrum.
11
(No Transcript)
12
XRF

• no gamma ray counterpart
• The XRF spectra are also well described by the
  Band function.

13

• X-ray rich GRB Epeak lt 50keV
• XRF Epeak at a few keV

14
XRF 020903

• Observations
• HETE-2
• the French Gamma Telescope (FREGATE)
• the wide-field X-ray monitor (WXM)
• the soft X-ray cameras (SXC)

15
French Gamma Telescope
16
Wide Field X-ray Monitor
17
Soft X-ray Camera
18
(No Transcript)
19
Temporal properties

• Two peaks 2-5 and 5-10 keV
• No significant flux above 10 keV
• The duration of the burst is longer in the lower
  energy band.
• ? this trend is similar to long bright GRBs.

20
(No Transcript)
21
(No Transcript)
22
Spectrum
23
(No Transcript)
24
(No Transcript)
25
(No Transcript)
26
The constrained Band function method

• Result
• Best-fit value Epeak 2.7 keV
• 1.1 keV lt Epeak lt 3.6keV with 68 probability
• Epeak lt 5.0 keV with 99.7 probability

27
(No Transcript)
28
(No Transcript)
29
Discussion

• XRF 020903 is an XRF and not a type I X-ray burst
• The observes spectrum of XRF 020903 were not the
  redshifted spectrum of a typical GRB.
• The properties of XRF 020903 are consistent with
  the relation between S7-30 and S30-400 found by
  Barraud et al.(2003)
• Figures 6-8 provide evidence that XRFs, X-ray
  rich GRBs, and GRBs from a continuum and are
  therefore the same phenomenon.

30
(No Transcript)
31
(No Transcript)
32
(No Transcript)
33
Thank you