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Speaker: Lluís Galbany, Institute of Space Sciences (IEEC-CSIC)
Title: TBC
Abstract:
The expansion rate of the Universe parameterized by the Hubble-Lemaître parameter H(z), has been a major endeavor in cosmology since the discovery of the expanding Universe. In the last years, significant effort has been put forth to measure with high precision its local value, the Hubble constant (H0), and today H0 is estimated from the distance ladder with an uncertainty of <3%. However, the estimation of H0 from the local distance ladder is in strong disagreement with the value inferred at high-redshift from the angular scale of fluctuations in the cosmic microwave background (CMB), possibly hinting towards new physics beyond the standard model (the Hubble tension). This discrepancy represents the most urgent puzzle of modern cosmology, and it is nowadays one of its hottest topics. In this seminar, I will prepare the base for introducing Hostflows, a Spanish nationally funded project that aims to advance towards solving of this tension from two different perspectives: (i) to perform an unprecedented study of the local environments of nearby standard candles, mapping their local properties (such as metallicity, stellar age and mass, and dust extinction) and constrain the effects in distance estimation and in the determination of the current expansion of the universe H0.; and (ii) to reconstruct the panorama of our supercluster Laniakea by studying cosmic flows using type Ia supernovae (SNe Ia) in the near- infrared (NIR), providing a sorely needed roadmap and means to expand the cosmography of the local universe and ultimately make accurate local measurements of H0 and the growth rate of cosmic structure parameterized by fσ8.