Tight correlations in ‘canonical’ lightcurves of G amma R ay B ursts

1. Tight correlations in ‘canonical’ lightcurves of Gamma Ray Bursts • M.G. Dainotti1, R. Willingale2, V .F. Cardone3, S. Capozziello4 , M. Ostrowski1 Dainotti et al. ApJL, 722, L 215 2010 + MNRAS, submitted 1)Jagellonian University, Krakow, Poland , 2) University of Leicester, United Kingdom3) Observatory of Roma, Frascati, Italy 4) University of Naples, Italy Gamma ray bursts (GRBs) observed up to redshifts z > 8 are fascinating Willingale et al (2007) model objects to study due to their still unexplained relativistic outburst mechanisms. Analysis of 77 GRB afterglows with known redshifts revealed a physical subsample of long GRBs with canonical plateau breaking to power-law light curves with a significant luminosity L*X(T*a) ≡ L*a - break time T*a correlation, in the GRB rest frame. Recently we extended the study to correlations between the afterglow characteristic luminosity L*aand the prompt emission quantities: 1.) the mean luminosity derived as <L*p>45=Eiso/T*45 2.)<L*p>90=Eiso/T*90 vs L*a • 3.)<L*p>Tp=Eiso/T*p vs L*a • 4.) the isotropic energyEiso L*a Conclusion: The afterglows with regular (“canonical”) light curves obey a tight LT physical scaling . The presence of (L*a,<L*p>45,) tight correlation, (also for <L*p>90,Eiso ) proves that afterglow plateau phase isrelated to the prompt emission. The highest LT correlated afterglow subsample for the GRBs with canonical X-ray light curves, leads also to highest prompt-plateau(L*a, <L*p>45 ) correlations, with ρ=0.98. log Lx(Ta)=log a +b log Ta Comparison of the characteristic time scales for the GRB prompt emission for all GRBs analyzed in this paper. The green points are the IC GRBs, the red ones are the long GRBs with u < 0.095 and the black ones are the other long GRBs with u < 4. Upper panel: log T*p vs log T*45distribution. Lower panel: log T*T90 vs T*45 distribution. The reference lines are T*90*2T*45 and T*45= T*p for the left and right panel respectively ρ=-0.76 b=-1.06±0.27 For u<4 Bologna, Italy L*x(Ta) vs T*a distribution for the sample of 62 long afterglows with u < 4, with the fitted correlation line in black. The upper red line is fitted to the 8 lowest error (red) points (presented separately in an inset panel). To analyze how accuracy of fitting the Willingale et al (2007) model - influence the studied correlations we define a fit error parameter • to distinguish the canonical shaped light curves from the more irregular ones Result : GRBswith regular afterglow light curves show higher correlations between their both afterglow and prompt emission physical properties Correlation coefficients ρ for the distributions (L*a,<L*p>45- red squares (L*a,<L*p>90) - black circles (L*a,<L*p>Tp ) - green asterixes (L*a,Eiso ) - blue square for the long GRB subsamples with the varying error parameter u. • regular afterglows obey a tight physical LT scaling: • very irregular afterglow light curves are dimmer • (L*a,<L*p>45,) (also <L*p>90,Eiso ) correlation proves the existence • of atight physical scaling between the prompt emission energetics and • the afterglow plateau phase, • Correlations between the physical properties of the prompt emission and the luminosity of the afterglow plateau reveals that only mean (averaged in time) energetic properties of the prompt emission clearly influence the afterglow plateau phase • to study GRB correlation look for regular light curve cases (L*a vs.<L*p>45for the u ≤ 4sample, with the fitted correlation dashed line in black. The red line is fitted to the 8 lowest error (red) points.