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Statistical Analysis of GRBs with Known Redshifts

G. Beskin, G. Greco, D. Badjin, S. Karpov, C. Bartolini, A. Guarnieri. Statistical Analysis of GRBs with Known Redshifts. Many faces of GRB phenomena -optics vs high energy SAO Workshop, October 12-16, 2009. From 970228 to 090929B:.

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Statistical Analysis of GRBs with Known Redshifts

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  1. G. Beskin, G. Greco, D. Badjin, S. Karpov, C. Bartolini, A. Guarnieri Statistical Analysis of GRBs with Known Redshifts Many faces of GRB phenomena -optics vs high energy SAO Workshop, October 12-16, 2009

  2. From 970228 to 090929B: • 787 GRBs localized within a few hours to days to less than 1 degree . Many faces of GRB phenomena -optics vs high energy SAO Workshop, October 12-16, 2009

  3. GRBswithSpectroscopyredshifts • Redshift distribution N total Mean Minimum Maximum 193 1,96 0,0085 8,26 Many faces of GRB phenomena -optics vs high energy SAO Workshop, October 12-16, 2009

  4. Our Sample: 87 long GRBs • with confirmed redshift • well-sampled light curves observed in R-band OpticalParameters • OpticalPeakFlux • First Observationafterγ-rayemission • IsotropicLuminosity kopt(z) is the cosmological correction that takes into account the transformation of the R passband in the proper GRB frame. Many faces of GRB phenomena -optics vs high energy SAO Workshop, October 12-16, 2009

  5. Our Sample: 87 long GRBs • with confirmed redshift • well-sampled light curves observed in R-band OpticalParameters by numerically integrating the afterglow in the interval from the earliest observation to the latest one • OpticalFluence • Optical Energy • R Band Many faces of GRB phenomena -optics vs high energy SAO Workshop, October 12-16, 2009

  6. Our Sample: 87 long GRBs • with confirmed redshift • well-sampled light curves observed in R-band OpticalParameters determined as the time since the afterglow detection during which 90 % of the optical fluence was received • OpticalDuration The delay of the optical peak relative to the time of burst detection in γ-ray • OpticalPeak Proper frame quantities are alsocalculated: = Many faces of GRB phenomena -optics vs high energy SAO Workshop, October 12-16, 2009

  7. Our Sample: 87 long GRBs • with confirmed redshift • well-sampled light curves observed in R-band OpticalParameters the flux decay with time in the dependence F t􀀀 at the initial observed afterglow phase. • Power-LawIndex In our sample there are 11 well-detected optical peaks that are not coincident with the work of the γ-ray activity phase. • Luminosity • OpticalPeak Many faces of GRB phenomena -optics vs high energy SAO Workshop, October 12-16, 2009

  8. Our Sample: 87 long GRBs • with confirmed redshift • well-sampled light curves observed in R-band OpticalParameters We consider the extrapolated optical luminosity Le immediately after the corresponding duration of the prompt - ray emission in the rest frame of the source. The extrapolation is performed using the slope calculated at early stage. We extrapolate the total energy Eto and total time duration Ttot of the optical afterglow. • Extrapolated • Luminosity • Total Optical Energy • Total OpticalDuration Many faces of GRB phenomena -optics vs high energy SAO Workshop, October 12-16, 2009

  9. Our Sample: 87 long GRBs • with confirmed redshift • well-sampled light curves observed in R-band γ-rayParameters • Peakγ-rayFlux ObservedPeakFlux • Peakγ-rayLuminosity kγ(z) is the k correction. FEis the spectral flux density, e1 and e2are the lower and upper boundaries of the energy range in which Fγ was obtained, E1 and E2 are the boundaries the energy range of interest in the proper burst frame.. Many faces of GRB phenomena -optics vs high energy SAO Workshop, October 12-16, 2009

  10. Our Sample: 87 long GRBs • with confirmed redshift • well-sampled light curves observed in R-band γ-rayParameters determined from published observations by reducing them to the energy range 15-150 keV. • γ-rayFluence • Isotropicγ-ray Energy Many faces of GRB phenomena -optics vs high energy SAO Workshop, October 12-16, 2009

  11. Our Sample: 87 long GRBs • with confirmed redshift • well-sampled light curves observed in R-band γ-rayParameters • Promptγ-rayemissionduration • observed we used the universally accepted parameter that is published in the results of γ-ray observations. • Promptγ-rayemissionduration • intrinsic Many faces of GRB phenomena -optics vs high energy SAO Workshop, October 12-16, 2009

  12. PairCorrelation: Intrinsic Frame Pearson correlation coefficients for the observed GRB parameters. Many faces of GRB phenomena -optics vs high energy SAO Workshop, October 12-16, 2009

  13. PairCorrelation: Observed Frame Pearson correlation coefficients for the observed GRB parameters. The observedquantitiesshow a weaker correlation, which is indicative of the actual physical relationships between the characteristics of afterglows in their proper reference frame. Many faces of GRB phenomena -optics vs high energy SAO Workshop, October 12-16, 2009

  14. Universal Optical Light CurveEoptversusLoptLoptversusTpeaK r= 0.76 r= 0.79 The observedcorrelationssuggest a universal underlying structure for optical afterglow emissions Many faces of GRB phenomena -optics vs high energy SAO Workshop, October 12-16, 2009

  15. Universal γ-rayLight CurveEisoversus Liso Tastedfor a large sample of 136 long GRBs. Tastedfor 6 Short GRBsdetecteduntilnow Eiso Eiso r= 0.98 r= 0.85 Liso Liso The observedcorrelationssuggest a universal underlying structure for the γ-rayemissions Many faces of GRB phenomena -optics vs high energy SAO Workshop, October 12-16, 2009

  16. LuminosityOpticalPeak Late time peaks are excluded (i.e GRB 970508). r = 0.9 (SL = 6.5 x 10 -8) The detectedcorrelationisconfirmed in new 5 opticalpeak light curves. Many faces of GRB phenomena -optics vs high energy SAO Workshop, October 12-16, 2009 Many faces of GRB phenomena -optics vs high energy SAO Workshop, October 12-16, 2009

  17. Discussion&Conclusion Our statistical analysis has tried to answer the following questions: • Is there evidence of cosmological evolution on γ-ray burst features? • Is there evidence of cosmological evolution on optical afterglow? • Despite the morphological differences between the high-energy emission and their afterglows, can we assume a universal underlying structure for both emissions ? • The intrinsic properties of prompt γ-ray emission show some degree of correlation with their afterglows or the afterglow 'forget' the initial physical conditions ? Many faces of GRB phenomena -optics vs high energy SAO Workshop, October 12-16, 2009

  18. Discussion&Conclusion • We have demonstrated, for a sample of 87 GRB with confirmed spectroscopic redshift, that the properties of the γ-ray emission are not affected by any cosmological evolution. • On the other hand the first stage of the afterglow evolution has a dependence on redshift and is even clearer if we consider the peaks that arise when the prompt γ-ray emission has been completely extinguished. • There are correlations between the luminosity, the total energy and the duration of the γ-ray and optical emission separately, which can arise from universal features of the observed light curves. • The intrinsic properties of prompt γ-ray emission show no degree of correlation with their afterglows. Many faces of GRB phenomena -optics vs high energy SAO Workshop, October 12-16, 2009

  19. OurReferences • Connections between parameters of GRB afterglows, Beskin, G. M.; Bartolini, C.; Cosentino, G.; Guarnieri, A.; Lodi, S.; Piccioni, A. GAMMA-RAY BURSTS: 5th Huntsville Symposium. AIP Conference Proceedings, Volume 526, pp. 355-359 (2000) • GRB Optical Afterglows: Correlation between Pair of Parameters, C. Bartolini,  G. Beskin,  G. Cosentino,  A. Guarnieri, A. Piccioni, A. Pozanenko,  Gamma-Ray Bursts in the Afterglow Era: Proceedings of the International Workshop Held in Rome, Italy, 17-20 October 2000, ESO ASTROPHYSICS SYMPOSIA. ISBN 3-540-42771-6. Edited by E. Costa, F. Frontera, and J. Hjorth. Springer-Verlag, 2001, p. 151 • GRBs with optical afterglow and known redshift: A statistical study, Il Nuovo Cimento B, vol. 121, Issue 12, p.1487-1488 G. Greco, D. Bad'in, G. Beskin, C. Bartolini, S. Karpov, A. Guarnieri, A. Piccioni, A. Biryukov, 2006. • Statistical Analysis of GRBs with Known Redshifts AIP Conference Proceedings, Volume 1065, pp. 75-78 G. Greco, G. Beskin, D. Bad'in, S. Karpov, C. Bartolini, A. Guarnieri, 2008. • Investigation of gamma-ray bursts with known redshifts: Statistical analysis of parameter , Astronomy Letters 35:1, 7-24 D. Bad'in, G. Beskin & G. Greco, 2009 Many faces of GRB phenomena -optics vs high energy SAO Workshop, October 12-16, 2009

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