New Cosmological Standard Candles from Gamma Ray B.. (Cosmological Candles)
New Cosmological Standard Candles from Gamma Ray Burst Correlations
Date du début: 1 févr. 2015,
Date de fin: 31 janv. 2018
Gamma Ray Bursts (GRBs), the most powerful and distant objects ever observed so far, are fascinating objects due to their still unexplained relativistic outburst mechanism. GRBs are observed much further than SNe Ia, which are the most robust probes of the accelerating Universe and whose discovery was awarded the Nobel Prize in 2011. For this reason, GRBscan be used to test cosmological models. Discovering universal relations linking observableGRB properties is a basic step toward using them as precise distance indicators for cosmologicalapplications. To this end, it is crucial to understand if they can be considered standard candles (astronomical objects whose luminosity is known or can be derived from other distance-independent observable) as SNe Ia and thus can be used as precise distance indicators for testing cosmological models.However, GRBs seem to be far from standard candles, with their energies spanning over eight orders of magnitude.Therefore, investigating relations between important GRB characteristics will shed light not only on their use as possible standard candles, but can also provide new constraints for the physical model of the GRB explosion mechanism. The project aim is to update in a multiwavelength range, from 0.3 keV to GeV, the luminosity-time correlation (LxTx)for GRBs (known in the literature as Dainotti relation) and identify a subclass of GRBs with well -defined properties and bias-free, namely corrected by redshift evolution and selection effects due to instrumental threshold through the Efron and Petrosian (1992) method. This subclass will be the candidate for GRBs standard candles.The bias-free LxTx correlation might be the basis for a new independent and powerful cosmological tool.Finally, the challenge is to use the LxTx correlation together with other correlations, both corrected for selection bias in order to discriminate among theoretical models, to use them as cosmological tools and valuable redshift estimators.
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