Dear colleagues and students,


We are glad to invite you to the next Rome Joint Astrophysics

Colloquium (JAC) on Wednesday the 20th of October at 16:30 CEST.

Please, note the time change for this colloquium.


Join the online JAC at:

To avoid issues with the connection, we encourage you to use the free

MS Teams App.


We would like to take this opportunity to meet in person, thus we will

be live streaming the seminar here at Physics Dept. of the Tor Vergata

University. Please, if you would like to join, fill out the following

form by Sunday October 17th. Form:


The Rome JAC is a joint initiative of the Physics Dept. of the Tor

Vergata University of Rome, INAF - Astronomical Observatory of Rome,

and INAF - Institute for Space Astrophysics and Planetology.


TITLE: New Determination of the Hubble Constant with Gaia EDR3,

Further Evidence of Excess Expansion


SPEAKER: Nobel Laureate Prof. A. Riess (Johns Hopkins University)


ABSTRACT: The Hubble constant remains one of the most important

parameters in the cosmological model, setting the size and age scales

of the Universe. Present uncertainties in the cosmological model

including the nature of dark energy, the properties of neutrinos and

the scale of departures from flat geometry can be constrained by

measurements of the Hubble constant made to higher precision than was

possible with the first generations of Hubble Telescope instruments. A

streamlined distance ladder constructed from infrared observations of

Cepheids and type Ia supernovae with ruthless attention paid to

systematics now provide <2% precision and offer the means to do much

better. By steadily improving the precision and accuracy of the Hubble

constant, we now see evidence for significant deviations from the

standard model, referred to as LambdaCDM, and thus the exciting

chance, if true, of discovering new fundamental physics such as exotic

dark energy, a new relativistic particle, or a small curvature to name

a few possibilities. I will review recent and expected progress, most

recently based on measurements from Gaia EDR3 .


Poster of the event is available at:


Best regards,


Marina Migliaccio

Francesco Tombesi


On behalf of the Rome JAC organizing committee