GB3 - Cosmology from GRBs |
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Speaker |
Dainotti, Maria Giovanna |
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Coauthors |
Vahe' Petrosian, Richard Willingale, Paul Obrien, Michal Ostrowski, Shigehiro Nagataki, Sergey Postnikov |
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Gamma Ray Bursts, selection effects in their correlations and their use as cosmological tools |
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Abstract |
We present here an update of the luminosity-time correlation (Lx-Ta) (Dainotti et al. 2008,2010,2011,2013) with a larger data sample of 127 GRBs with well sampled lightcurves. Since some of this correlation could result from the redshift dependences of these intrinsic parameters, namely their cosmological evolution we use the Efron-Petrosian (EP) method to reveal the intrinsic nature of this correlation. We find that a substantial part of the correlation is intrinsic and describe how we recover it and how this can be used to constrain physical models of the plateau emission, whose origin is still unknown. The same methodology has been applied for the Luminosity in the prompt-Time prompt correlation (Dainotti et al. 2015). We show how changes of the observed slope, of the Lx-Ta correlation in GRB afterglows affect the determination of the cosmological parameters. With 101 GRBs simulated with a central value of bobs that differs on the intrinsic one by a 5σ factor, we find an overestimated value of the matter density parameter, ΩM compared to the value obtained with SNe Ia, while the Hubble constant, H0, best fit value is still compatible in 1 σ. Instead, for a subsample of high luminous GRBs (HighL), H0 and ΩM are not more compatible in 1 σ and ΩM is underestimated by the 13%. We conclude that any approach that involves cosmology should take into consideration only intrinsic correlations not the observed ones. We finally show how the intrinsic correlation used for cosmology can be complimentary to the SNe Ia as a cosmological probe. |
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