Daisuke YONETOKU (Kanazawa Univ.) T. Murakami (Kanazawa Univ.), R. Tsutsui, T. Nakamura (Kyoto...
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Transcript of Daisuke YONETOKU (Kanazawa Univ.) T. Murakami (Kanazawa Univ.), R. Tsutsui, T. Nakamura (Kyoto...
Daisuke YONETOKU (Kanazawa Univ.) T. Murakami (Kanazawa Univ.),R. Tsutsui, T. Nakamura (Kyoto Univ.),K. Takahashi (Nagoya Univ.)
The Spectral Ep–Lp and Ep–Eiso Relations:
The Origin of Dispersion and Its Improvement
GRB Cosmology Project
102 known redshift samples with ( Ep, 1 sec peak flux, fluence ).Lp is calculated by 1 sec peak flux in the obs. frame.
νFν
∝ Eα
∝ Eβ
ピークエネルギー (Ep)
Briggs et al. 2000
■ Application for the GRB Cosmology■ Investigate the characteristic of GRB itself
Introduction
C.C. = 0.890d.o.f. = 100
Tully-Fisher Relation (Rotation–Luminosity)
Type Ia Supernovae
HR diagram
Cepheid Variable(Period–Luminosity)
parallaxredshift
z = 1.755
Cosmic Distance Ladder (Distance Indicators) When we measure the energy density of D-E and D-M,
we need “distance” and “redshift” relation.
Just after the Big B
ang (CM
B)
L ≡ 4πdL2 F
Gamma-Ray Bursts z = 8.2 !
z = 1.755
Calibrated Epeak-Luminosity relation52 GRBs ( z<1.755 )
Epeak(1+z) [keV]
Pea
k Lu
min
osity
[1051
erg
/sec
]
Lp = 5.93 x 1047 [ Epeak (1+z) ]1.85
5.93 x 1047 [ Epeak (1+z) ]1.85
4πFdL 2 =
Redshift
Lum
inos
ity D
ista
nce
(cm
)10
2610
2710
2810
29
0.01 0.1 1 10
Type Ia SNe New!GRB
CalibratedGRB
Hubble Diagram ( 1.8 < z < 8.2)■ GRB data (z < 1.755)■ GRB data (1.755 < z < 8.2)+ Type Ia SNe
(Ωm, ΩΛ) = (1, 0)
(0.3, 0.7)
(0, 1)
z = 8.2
ΩΛ
Cosmological Parameters (1.8 < z < 8.2 )D
ark
Ene
rgy
: ΩΛ
Matter : Ωm
( 0.24±0.10 , 0.76±0.10)(Ωm, ΩΛ) =
First Measurement of DM & DEin the early universe of z > 2.
Tsutsui, DY + (2009)
( flat universe )
Poster-094Tsutsui et al.
Origin of Data Dispersions
Peak Flux Redshift
We classified 102 GRB events into 3 groups,according to the bolometric peak flux and the redshift.
We found a redshift evolution in the Ep-Lp relation in 2 s significance, but there is no peak flux dependence.
Ep-Lp Ep-LpBrightMiddleDim
High-zMiddle-zLow-z
We systematically overestimate the peak luminosityfor higher redshift GRBs.
Rel
ativ
e P
eak
Flux
in O
bs. F
ram
e
Time Scale of Peak Flux (sec)
64msec512msec
1024msec
Redshift Evolution ?
1sec@ z=0
1sec@ z=1
1sec@ z=2
Original Ep – Lp
58 GRBs Konus & Swift
~ 3 sec
31 Konus data
2088 msec ~ 3 sec
Redefinition of the peak luminosity ( Lp,GRB )
We searched the best time scalefor the peak luminosity in the GRB frame.
Time Scale of Peak Luminosity in GRB Frame (sec)
Cor
rela
tion
Coe
ffici
ent
Lp = 1048.70 [ Ep(1+z) ]1.46
Deviation : σsys = 0.213
1sec Peak Luminosity ( measured in Obs. frame )
Cor. Coef = 0.890
Ep (1+z) [keV]
Pea
k Lu
min
osity
[erg
/sec
]
Lp = 1048.18 [ Ep(1+z) ]1.53
Deviation : σsys = 0.180
3sec Peak Luminosity (measured in GRB frame )
Cor. Coef = 0.921
Ep (1+z) [keV]
Pea
k Lu
min
osity
[erg
/sec
]
Fluence Redshift
Ep-Eiso Ep-Eiso
We found a fluence dependence in the Ep-Eiso relation in 2 s significance, but there is no redshift evolution.
Similar analysis for the Ep – Eiso relation.
BrightMiddleDim
High-zMiddle-zLow-z
■ We measured the cosmological parameters,
1.755 < z < 8.2( 0.24±0.10 , 0.76±0.10 )(Ωm, ΩΛ) =
■ We succeeded in extending the cosmic distance ladder toward z=8.2 with the Ep – Lp relation.
Redshift evolution
Peak Flux/Fluence Dependence
Ep – Lp Yes (2s C.L.) NoEp – Eiso No Yes (2s C.L.)
■ Possible origins of data dispersion
■ Using the NEW definition of “Lp,GRB (~ 3sec in GRB frame)”, we succeeded in canceling the redshift evolution, and in improving the Ep – Lp relation.
Summary