Bright high z SnIa: A challenge for Lambda CDM
Φόρτωση...
Ημερομηνία
Συγγραφείς
Perivolaropoulos, L.
Shafieloo, A.
Τίτλος Εφημερίδας
Περιοδικό ISSN
Τίτλος τόμου
Εκδότης
Περίληψη
Τύπος
Είδος δημοσίευσης σε συνέδριο
Είδος περιοδικού
peer reviewed
Είδος εκπαιδευτικού υλικού
Όνομα συνεδρίου
Όνομα περιοδικού
Physical Review D
Όνομα βιβλίου
Σειρά βιβλίου
Έκδοση βιβλίου
Συμπληρωματικός/δευτερεύων τίτλος
Περιγραφή
It has recently been pointed out by Kowalski et. al. [Astrophys. J. 686, 749 (2008).] that there is "an unexpected brightness of the SnIa data at z > 1." We quantify this statement by constructing a new statistic which is applicable directly on the type Ia supernova (SnIa) distance moduli. This statistic is designed to pick up systematic brightness trends of SnIa data points with respect to a best fit cosmological model at high redshifts. It is based on binning the normalized differences between the SnIa distance moduli and the corresponding best fit values in the context of a specific cosmological model (e.g. Lambda CDM). These differences are normalized by the standard errors of the observed distance moduli. We then focus on the highest redshift bin and extend its size toward lower redshifts until the binned normalized difference (BND) changes sign (crosses 0) at a redshift z(c) (bin size N(c)). The bin size N(c) of this crossing (the statistical variable) is then compared with the corresponding crossing bin size N(mc) for Monte Carlo data realizations based on the best fit model. We find that the crossing bin size N(c) obtained from the Union08 and Gold06 data with respect to the best fit Lambda CDM model is anomalously large compared to N(mc) of the corresponding Monte Carlo data sets obtained from the best fit Lambda CDM in each case. In particular, only 2.2% of the Monte Carlo Lambda CDM data sets are consistent with the Gold06 value of N(c) while the corresponding probability for the Union08 value of N(c) is 5.3%. Thus, according to this statistic, the probability that the high redshift brightness bias of the Union08 and Gold06 data sets is realized in the context of a (w(0), w(1)) = (-1, 0) model (Lambda CDM cosmology) is less than 6%. The corresponding realization probability in the context of a (w(0), w(1)) = (-1.4, 2) model is more than 30% for both the Union08 and the Gold06 data sets indicating a much better consistency for this model with respect to the BND statistic.
Περιγραφή
Λέξεις-κλειδιά
gamma-ray bursts, anisotropy-probe observations, galaxy redshift survey, equation-of-state, dark energy, cosmological constant, supernova data, accelerating universe, observational status, expansion history
Θεματική κατηγορία
Παραπομπή
Σύνδεσμος
<Go to ISI>://000267701500021
http://prd.aps.org/abstract/PRD/v79/i12/e123502
http://prd.aps.org/abstract/PRD/v79/i12/e123502
Γλώσσα
en
Εκδίδον τμήμα/τομέας
Όνομα επιβλέποντος
Εξεταστική επιτροπή
Γενική Περιγραφή / Σχόλια
Ίδρυμα και Σχολή/Τμήμα του υποβάλλοντος
Πανεπιστήμιο Ιωαννίνων. Σχολή Επιστημών και Τεχνολογιών. Τμήμα Βιολογικών Εφαρμογών και Τεχνολογιών