1 / 22

Evolution of the E peak vs. Luminosity Relation for Long GRBs

Evolution of the E peak vs. Luminosity Relation for Long GRBs. W.J. Azzam & M.J. Alothman Department of Physics University of Bahrain Kingdom of Bahrain wjazzam@sci.uob.bh. Outline 1- Luminosity Indicators 2- Data Sample 3- Earlier Work 4- Current Results 5- Conclusion.

shanna
Download Presentation

Evolution of the E peak vs. Luminosity Relation for Long GRBs

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Evolution of the Epeak vs. Luminosity Relation for Long GRBs W.J. Azzam& M.J. Alothman Department of Physics University of Bahrain Kingdom of Bahrain wjazzam@sci.uob.bh

  2. Outline1- Luminosity Indicators2- Data Sample3- Earlier Work4- Current Results5- Conclusion

  3. Energy Relations / Luminosity Indicators 1-Lag relation (L – lag) 2-Variability relation (L – V) 3-Amati relation (Ep – Eiso ) 4- Yonetoku relation (Ep – Liso) 5- Ghirlanda relation (Ep – E) 6- Liang-Zhang relation (Ep – Eiso – tb) 7- “Firmani” relation (Ep – Liso – T0.45) more to come …

  4. The importance of these relations lies in: 1- Their potential use as cosmological probes. For instance, to constrain M and (Ghirlanda et al. 2006; Capozziello & Izzo 2008; Amati et al. 2008). 2- Insight into the physics of GRBs.

  5. Some generalized tests have been carried out to check the robustness of these relations (Schaefer & Collazi 2007) and in fact to produce a GRB Hubble diagram (Schaefer 2007).

  6. On the other hand, some studies have tried to deal with the problems of circularity and selection effects: Li et al. (2008) Butler et al. (2008) Ghirlanda et al. (2008) Nava et al. (2009)

  7. General purpose of our study: do some (or all) of these relations evolve with z? • In an earlier study(Azzam, Alothman, & Guessoum 2008) we looked at the possible evolution of: 1- the time-lag, lag, relation 2- the variability, V, relation • In this study we consider: possible evolution of the Epeak vs. L relation. • Data sample: 69 GRBs taken from Schaefer (2007).

  8. Earlier Results The entire data sample consists of 69 GRBs, of which 38 have lag values and 51 have V values.The method consists of binning the data by redshift, z, then writing the time-lag relation in the form: log(L) = A + B log[lag / (1+z)] and extracting the fit parameters A and B for each redshift bin.

  9. Likewise, for the variability relation, which we write in the form: log(L) = A + B log[V (1+z)]. The objective is then to see whether the fitting parameters A and B evolve in any systematic way with the redshift.

  10. Note that the binning was done in two ways for each of the two relations: Binning by number in which the number of bursts per bin was fixed. Binning by width in which the z was fixed.

  11. Figure 1. The best fit lines for the three redshift bins (binning by number) that are presented in Table 1 for the lag-relation, showing a systematic variation of the A and B parameters with redshift.

  12. Figure 2. The best fit lines for the three redshift bins (binning by number) that are presented in Table 2 for the variability relation, showing no systematic variation of the A and B parameters with redshift.

  13. Current Study We write the Epeak vs. L relation in the form: log(L) = A + B log[Epeak (1+z)] Again, we bin the data, extract the fitting parameters A and B, and see whether they evolve in any systematic way with redshift.

  14. Conclusion In this study, a sample consisting of 69 GRBs was used to investigate the possible evolution of the Epeak vs. L relation. The data was binned in redshift, and the fit parameters A and B were extracted. The parameters A and B showed no systematic dependence on z, and hence the Epeak–L relation does not seem to evolve in any systematic way with redshift.

  15. References • Amati, L. et al. 2002, A&A, 390, 81 • Amati, L. 2006, MNRAS, 372, 233 • Amati, L. et al. 2008, (arXiv:0805.0377) • Butler, N.R. et al. 2008, (arXiv:0802.3396) • Capozziello, S. & Izzo, L. 2008, (arXiv:0806.1120) • Fenimore, E.E., & Ramirez-Ruiz E. 2000, (astro-ph/0004176) • Ghirlanda, G. et al. 2004, ApJ, 616, 331 • Ghirlanda, G. et al. 2006, A&A, 452, 839 • Ghirlanda, G. et al. 2008, (arXiv:0804.1675) • Li, H. et al. 2008, ApJ, 680, 92 • Liang, E. & Zhang, B. 2005, ApJ, 633, L611 • Norris, J.P. et al. 2000, ApJ, 534, 248 • Schaefer, B.E. 2007, ApJ, 660, 16 • Schaefer, B.E. & Collazi, A.C. 2007, ApJ, 656, L53 • Yonetoku, D. et al. 2004, ApJ, 609, 935

More Related