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Daisuke YONETOKU (Kanazawa Univ.) T. Murakami (Kanazawa Univ.),

The Spectral Ep–Lp and Ep–Eiso Relations: The Origin of Dispersion and Its Improvement. Daisuke YONETOKU (Kanazawa Univ.) T. Murakami (Kanazawa Univ.), R. Tsutsui , T. Nakamura (Kyoto Univ.), K. Takahashi (Nagoya Univ.). GRB Cosmology Project. yonetoku@astro.s.kanazawa-u.ac.jp.

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Daisuke YONETOKU (Kanazawa Univ.) T. Murakami (Kanazawa Univ.),

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  1. The Spectral Ep–Lp and Ep–Eiso Relations: The Origin of Dispersion and Its Improvement Daisuke YONETOKU (Kanazawa Univ.) T. Murakami (Kanazawa Univ.), R. Tsutsui, T. Nakamura (Kyoto Univ.), K. Takahashi (Nagoya Univ.) GRB Cosmology Project yonetoku@astro.s.kanazawa-u.ac.jp

  2. Introduction 102 known redshift samples with ( Ep, 1 sec peak flux, fluence ). Lp is calculated by 1 sec peak flux in the obs. frame. C.C. = 0.890 d.o.f. = 100 Briggs et al. 2000 ∝ Eα ∝ Eβ νFν ■ Application for the GRB Cosmology ■ Investigate the characteristic of GRB itself ピークエネルギー (Ep)

  3. 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) z = 8.2 ! Gamma-Ray Bursts z = 1.755 Type Ia Supernovae Tully-Fisher Relation (Rotation–Luminosity) Cepheid Variable (Period–Luminosity) HRdiagram redshift z = 1.755 L ≡ 4πdL2 F parallax

  4. Calibrated Epeak-Luminosity relation 52 GRBs（z<1.755） Peak Luminosity [1051 erg/sec] Lp = 5.93 x 1047 [Epeak (1+z) ]1.85 5.93 x 1047 [ Epeak (1+z) ]1.85 dL2 = 4πF Epeak(1+z) [keV]

  5. (Ωm, ΩΛ) = (1, 0) Hubble Diagram ( 1.8 < z < 8.2) (0.3, 0.7) ■ GRB data (z < 1.755) ■ GRB data (1.755 < z < 8.2) ＋ Type IaSNe (0, 1) 1029 z = 8.2 1028 Luminosity Distance (cm) New! GRB Type IaSNe 1027 Calibrated GRB 1026 0.01 0.1 1 10 Redshift

  6. Tsutsui, DY + (2009) Cosmological Parameters (1.8 < z < 8.2 ) ΩΛ Dark Energy : ΩΛ Poster-094 Tsutsui et al. Matter : Ωm (Ωm, ΩΛ) = ( 0.24±0.10 , 0.76±0.10) ( flat universe ) First Measurement of DM & DEin the early universe of z > 2.

  7. Origin of Data Dispersions We classified 102 GRB events into 3 groups, according to the bolometric peak flux and the redshift. Redshift Peak Flux Ep-Lp Ep-Lp Bright Middle Dim High-z Middle-z Low-z We found aredshift evolution in the Ep-Lp relation in 2 s significance, but there is no peak flux dependence.

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

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

  10. 1secPeak Luminosity ( measured in Obs. frame ) Lp = 1048.70 [ Ep(1+z) ]1.46 Cor. Coef = 0.890 Peak Luminosity [erg/sec] Deviation : σsys = 0.213 Ep (1+z) [keV]

  11. 3secPeak Luminosity (measured in GRB frame ) Lp = 1048.18 [ Ep(1+z) ]1.53 Cor. Coef = 0.921 Peak Luminosity [erg/sec] Deviation : σsys = 0.180 Ep (1+z) [keV]

  12. Similar analysis for the Ep – Eiso relation. Fluence Redshift Ep-Eiso Ep-Eiso Bright Middle Dim High-z Middle-z Low-z We found afluence dependence in the Ep-Eiso relation in 2 s significance, but there is no redshift evolution.

  13. Summary ■ We succeeded in extending the cosmic distance ladder toward z=8.2 with the Ep – Lp relation. ■ We measured the cosmological parameters, 1.755 < z < 8.2 ■ Possible origins of data dispersion ( 0.24±0.10 (Ωm, ΩΛ) = , 0.76±0.10) ■ 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.

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