Deciphering the Ancient Universe with Gamma-Ray Bursts
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Transcript of Deciphering the Ancient Universe with Gamma-Ray Bursts
Deciphering the Ancient Universe with Gamma-Ray
BurstsNobuyuki Kawai (Tokyo Tech)
http://www-tap.scphys.kyoto-u.ac.jp/GRB2010/
Cosmic Time
Neutral opaque Universe Ionized
transparent Universe
GRB as a probe for high-z UniverseGRB as a luminous light source
GRB as a mark for a death of a massive star
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Imprints in GRB spectra
Molecular Cloud
H II Region
WR Wind Shell
SN ejecta
galaxy ISM
IGM
Ejecta CSM SFR ISM IGM
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Lya break
SII
SiII*OI CII
SiII
GRB 050904 at t=3.4 d
Subaru FOCAS 4.0 hrs, l/Dl»1000Kawai et al. (2006)Totani et al. (2006)
[S/H]=-1.3
Log NHI=21.6
zIGM,u = zDLA = 6.295 best fit xHI = 0.00 xHI < 0.17 (68 %
C.L.) 0.60 (95%
C.L.)
History of the Universe
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• Reinization• Chemical
evolution• Star formation
rate
IGM
Neu
tral F
ract
ion
Met
allic
ity
Cos
mic
star
form
atio
n ra
te
“Tanvir Plot”
Tanvir 2009
GRBs
Galaxies
Quasars
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960 970 980 wavelength [nm]
2 1 0 Flux density
Lya
700 800 900 1000 wavelength [nm]
1
0
Lya
S+
Si+Si+
O C+
800 900 1000 wavelength [nm]
30
20
10
0
Lya
optical/NIR spectra of highest-z objectsGalaxyz = 6.96
Quasarz = 6.4
GRBz = 6.3
•Lyman alpha emitter•can be found with
systematic wide-field narrow band survey + spectroscopy•little information in
spectra (e.g. metal?)•luminosity selected
•very rare: only 10 at z>6 in SDSS•steadily bright•complicated
spectra: difficult to interpret•proximity effect•luminosity-
selected
•rare: ~<5% at z>6 ?•bright at early phase•simple intrinsic
spectra: abundant information
•no proximity effect•sampling normal
star-forming glaxy
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Agenda What do we know about GRBs? What do we know about the
ancient Universe? How can we use GRBs to
understand the history of the Universe?
What are the future prospects?
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Poster Competition Eligible if you are not giving a
talk Indicate your entry by the color
sticker Entry closed at Monday afternoon
Anonymous Judges choose three winners
Winners give 10 min talk on Friday
Young participants (students, postdocs) are particularly encouraged
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Cosmic Chemical Evolution
Fynbo et al. 2006Prochaska et al. 2003Sollerman et al. 2005Savaglio, et al. 2009
GRB 050904Kawai et al. 2006
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Reionization
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Star Formation Rate