grb050502b optical and x-ray light curves
Post on 31-Jan-2016
30 Views
Preview:
DESCRIPTION
TRANSCRIPT
GRB050502B optical and X-ray light curves
Paulo Afonso
Working with:
Jochen Greiner, Elena Pian, Aybüke Yoldaş
- with the collaboration of Daniele Malesani, Stefano Covino, Thomas Krühler
Schloss Ringberg meeting
21-2-2008
Paulo Afonso - Schloss Ringberg, 21-2-2008
2
Bright x-ray flares are superposed on underlying power-law decay (solid line). Possible jet break at ~ 1 day (100 000 sec) postburst. From Burrows et alia, 2005
Paulo Afonso - Schloss Ringberg, 21-2-2008
3
Conspicuous characteristics
• X-Ray flare has ~ same energy (~9x10-7 erg/cm2, 0.3-10 keV) as the prompt emission observed by BAT (~8x10-7 erg/cm2, 15-350 keV). This was never observed before!
• Early fainter afterglow than other XRT-detected, but rapid brightening several minutes later
• Bumpiness continues at late-time, before decaying back to preflare fluxes (Burrows et al, 2005)
Paulo Afonso - Schloss Ringberg, 21-2-2008
4
Explanations/models
• Continued activity in the internal engine is required – not associated with the afterglow external shock, because:
• Rise and decay times of flare are very fast
• The afterglow started already before the flare (same time decay index before and after flare)
• Later bumpiness not so easy to explain: maybe internal engine & afterglow shock together (Falcone et al., 2006)
Paulo Afonso - Schloss Ringberg, 21-2-2008
5
But things are more complex: flares, plateaus, chromatic breaks. (Figure from Panaitescu, 2007)
Paulo Afonso - Schloss Ringberg, 21-2-2008
6
Work in progress: reduce data again, for better optical photometry
Preliminary light curve:
Data points from TNG and ANU.
Note steep decay at t~ 1 day in the I-Band.
Time correlation with end of 2nd X-ray flare?
Paulo Afonso - Schloss Ringberg, 21-2-2008
7
Final science image
(combining 2 images)
TNG 1for I band.
Problems:bad pixels,
fringing effects
Paulo Afonso - Schloss Ringberg, 21-2-2008
8
TNG 3 final science
image for I band.
Glare: due to problem in
automatic flat
procedure.
Paulo Afonso - Schloss Ringberg, 21-2-2008
9
TNG 1 Vs. TNG 3 – fringes “disappear” because of higher number of combined science images. Normally a higher number is
required for successful removal of fringes. We are looking for more data in archives of TNG right now.
Paulo Afonso - Schloss Ringberg, 21-2-2008
10
TNG2 I band – fringes removed with just 2 individual images
Paulo Afonso - Schloss Ringberg, 21-2-2008
11
TNG3 I band – even with many individual images, removal of fringing seems now more effective
Paulo Afonso - Schloss Ringberg, 21-2-2008
12
TNG2 I band without fringes: very first crude
photometry – not so bad!
In this image:
22.33 +/- 0.27
former image:
22.10 +/- 0.16
Paulo Afonso - Schloss Ringberg, 21-2-2008
13
Next steps – ongoing work:
• Fringe effects removal/reduction on TNG1
• Photometry of TNG3 – very faint object!!?
• Photometry of TNG2 R band
• Use of further TNG archive images to make better fringe patterns
top related