Transition redshift: new kinematic constraints from supernovae

Autor(es)

Cunha, J. V. ^[1] ; Lima, J. A. S. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Dept Astron, BR-05508900 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Monthly Notices of the Royal Astronomical Society; v. 390, n. 1, p. 210-217, OCT 11 2008.
• Citações Web of Science: 67

Resumo

The transition redshift (deceleration/acceleration) is discussed by expanding the deceleration parameter to first order around its present value. A detailed study is carried out by considering two different parametrizations, q = q(0) + q(1)z and q = q(0) + q(1)z(1 + z)(-1), and the associated free parameters (q(0), q(1)) are constrained by three different supernovae (SNe) samples. A previous analysis by Riess et al. using the first expansion is slightly improved and confirmed in light of their recent data (Gold07 sample). However, by fitting the model with the Supernova Legacy Survey (SNLS) type Ia sample, we find that the best fit to the redshift transition is z(t) = 0.61, instead of z(t) = 0.46 as derived by the High-z Supernovae Search (HZSNS) team. This result based in the SNLS sample is also in good agreement with the sample of Davis et al., z(t) = 0.60(-0.11)(+0.28) (1 sigma). Such results are in line with some independent analyses and accommodate more easily the concordance flat model (Lambda CDM). For both parametrizations, the three SNe Ia samples considered favour recent acceleration and past deceleration with a high degree of statistical confidence level. All the kinematic results presented here depend neither on the validity of general relativity nor on the matter-energy contents of the Universe. (AU)

• Processo FAPESP: 05/02809-5 - Investigando as componentes escuras do universo com raios-X, SNE IA, RCF, efeito Sunyaev-Zel'dovich e idades de objetos velhos
• Beneficiário: João Vital da Cunha Júnior
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado