CCAPP Seminar: "Early dark energy as a solution to the Hubble tension" Tanvi Karwal (Johns Hopkins)

July 27, 2018
Tuesday, October 16, 2018 - 11:30am to 12:30pm
PRB 4138
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Although the standard Lambda-CDM model of cosmology is in excellent agreement with the observed cosmic microwave background (CMB) power spectrum, its prediction for the current rate of expansion of the universe is in tension with observations of the local universe at > 3 sigma, with local measurements preferring a higher value. 
Tanvi's talk will present a solution to the Hubble tension that modifies the early expansion history of the Universe through the addition of an early dark energy component. This behaves like a cosmological constant at early times and then decays away quickly with redshift as (1+z)^6 at some critical time. It therefore only influences the Universe over a small range in redshift. 
If such a field becomes dynamical before recombination, it increases the pre-recombination expansion rate and shifts the peaks in the CMB power spectrum to smaller angular scales. These can be brought back in agreement with observations by an increase in the predicted value of H0, reducing the Hubble tension. 
Tanvi will present constraints to this model and discuss its effectiveness in diminishing the tension. 
 

 

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