Conveners
The Hubble constant day @UniFE
- Piero Rosati (Dipartimento di Fisica e Scienze della Terra, UniFe)
- Paolo Natoli (Dipartimento di Fisica e Scienze della Terra, UniFe)
- Cristiano Guidorzi (Dipartimento di Fisica e Scienze della Terra, UniFe)
Description
The Hubble constant is a fundamental cosmological parameter, which defines critical scales of the Universe such as its size, age and expansion rate. Its current value (H0) is determined by the total matter-density content of the Universe and its evolution across cosmic history. The measurement of H0 has dominated astronomy and observational cosmology for decades, since its first estimate in 1926 when the Hubble-Lemaître law was first discovered. Its uncertainty, which was up to a factor of two until 20 years ago, has very recently collapsed to only a few % from three independent measurements. Very interestingly, the latest measurements in the early Universe using Planck Cosmic Microwave Background data and at late epochs with astronomical distance indicators point to a significant (>4 sigma) tension on the H0 value. Other independent methods, particularly those based on gravitational lensing time delay support the H0 local value. Since the standard Lambda Cold Dark Matter (LCDM) cosmological model is used to compare the H0 measurement in the early and late Universe, there is increasing evidence that such a discrepancy might be due to some feature altering the standard assumptions on the matter-energy content of the Universe or other fundamental assumptions within LCDM, i.e. new physics. Three of these methods to measure H0 are part of active lines of research in our Department, including a new technique based on the identification of gravitational wave events which are set to increase dramatically in coming years. In this one-day workshop, leading experts in each field will review the status of the Hubble constant measurements to date, as well as our current theoretical models and the new challenges, in a field which is at the crossroad of astrophysics, cosmology and fundamental physics.
