Alternative type Ia supernova standardization methods and the Hubble tension

• Grant number: 24/08047-0
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: October 01, 2024
• End date: February 29, 2028
• Field of knowledge: Physical Sciences and Mathematics - Astronomy - Extragalactic Astrophysics
• Principal Investigator: Edivaldo Moura Santos
• Grantee: Alexandra Turmina Petreca
• Host Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The goal of the current PhD proposal in observational cosmology is to study the tension in the Hubble constant (H0). The tension refers to the difference between the values of H0 obtained from statistical properties of the cosmic microwave background fluctuations and from the cosmic distance ladder, the latter dependent on two classes of reference objects, cepheid variables and type Ia supernovae (SNIa). There is a consensus nowadays that the determination of H0 based on the distance ladder is limited by the systematic uncertainty associated to the standardization of magnitudes of the reference objects, especially the SNIa. In particular, the dependence of the SNIa magnitudes with properties of the host galaxy is crucial to the understanding of the residuals observed in the Hubble flow diagram of these objects. Among these properties, we can identify extinction caused by dust in the host galaxy. We propose here a study of the evolution of dust extinction coefficients and the impact of different models for such coefficients in the Hubble flow of SNIa from the Pantheon+ sample used in the construction of the cosmic distance ladder together with cepheids from the SHOES sample.