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. 102 known redshift samples with ( Ep, 1 sec peak flux, fluence ). Lp is calculated by 1 sec peak flux in the obs. frame. νF ν ∝ E α ∝ E β ピークエネルギー (Ep) Briggs et al ■ Application for the GRB Cosmology ■ Investigate the characteristic of GRB itself ■ Application for the GRB Cosmology ■ Investigate the characteristic of GRB itself Introduction C.C. = d.o.f. = 100

Tully-Fisher Relation (Rotation–Luminosity) Type Ia Supernovae HR diagram Cepheid Variable (Period–Luminosity) parallax redshift z = 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 Bang (CMB) L ≡ 4 π d L 2 F Gamma-Ray Bursts z = 8.2 ! z = 1.755

Calibrated Epeak-Luminosity relation 52 GRBs （ z<1.755 ） Epeak(1+z) [keV] Peak Luminosity [10 51 erg/sec] Lp = 5.93 x [ E peak (1+z) ] x [ E peak (1+z) ] πF4πF d L 2 =

Redshift Luminosity Distance (cm) Type Ia SNe New! GRB Calibrated GRB Hubble Diagram ( 1.8 < z < 8.2) ■ GRB data (z < 1.755) ■ GRB data (1.755 < z < 8.2) ＋ Type Ia SNe ( Ω m, Ω Λ ) = (1, 0) (0.3, 0.7) (0, 1) z = 8.2

ΩΛΩΛ Cosmological Parameters (1.8 < z < 8.2 ) Dark Energy : Ω Λ Matter : Ω m ( 0.24 ±0.10, 0.76 ±0.10 ) (Ω m, Ω Λ ) = First Measurement of DM & DE in the early universe of z > 2. Tsutsui, DY + (2009) ( flat universe ) Poster-094 Tsutsui et al. Poster-094 Tsutsui 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. We found a redshift evolution in the Ep-Lp relation in 2 s significance, but there is no peak flux dependence. Ep-Lp Bright Middle Dim High-z Middle-z Low-z

We systematically overestimate the peak luminosity for higher redshift GRBs. Relative Peak Flux in Obs. Frame Time Scale of Peak Flux (sec) 64msec 512msec 1024msec Redshift Evolution ? z=0 z=0 z=1 z=1 z=2 z=2

Original Ep – Lp 58 GRBs Konus & Swift ~ 3 sec 31 Konus data 2088 msec ~ 3 sec 2088 msec ~ 3 sec Redefinition of the peak luminosity ( Lp, GRB ) We searched the best time scale for the peak luminosity in the GRB frame. Time Scale of Peak Luminosity in GRB Frame (sec) Correlation Coefficient

Lp = [ Ep(1+z) ] 1.46 Deviation : σ sys = sec Peak Luminosity ( measured in Obs. frame ) Cor. Coef = Ep (1+z) [keV] Peak Luminosity [erg/sec]

Lp = [ Ep(1+z) ] 1.53 Deviation : σ sys = sec Peak Luminosity (measured in GRB frame ) Cor. Coef = Ep (1+z) [keV] Peak Luminosity [erg/sec]

FluenceRedshift Ep-Eiso We found a fluence dependence in the Ep-Eiso relation in 2 s significance, but there is no redshift evolution. 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. Bright Middle Dim High-z Middle-z Low-z

■ We measured the cosmological parameters, < z < 8.2 ( 0.24 ±0.10, 0.76 ±0.10 ) ( Ω m, Ω Λ ) = ■ 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 (2 s C.L.) No Ep – EisoNo Yes (2 s 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