CWRU PAT Coffee Agenda

Tuesdays 10:30 - 11:30 | Fridays 11:30 - 12:30

+1 de Sitter Decays to Infinity.

oxg34 +1

+1 Implications for the Hubble tension from the ages of the oldest astrophysical objects.

cjc5 +1

0 Relic Cosmological Vector Fields and Inflationary Gravitational Waves.

bump   gds6 +1

Showing votes from 2021-05-21 12:30 to 2021-05-25 11:30 | Next meeting is Tuesday Aug 26th, 10:30 am.

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astro-ph.CO

  • Implications for the Hubble tension from the ages of the oldest astrophysical objects.- [PDF] - [Article]

    Sunny Vagnozzi, Fabio Pacucci, Abraham Loeb
     

    We use the ages of old astrophysical objects (OAO) in the redshift range $0 \lesssim z \lesssim 8$ as stringent tests of the late-time cosmic expansion history. Since the age of the Universe at any redshift is inversely proportional to $H_0$, requiring that the Universe be older than the oldest objects it contains at any redshift, provides an upper limit on $H_0$. Using a combination of galaxies imaged from the CANDELS program and various high-$z$ quasars, we construct an age-redshift diagram of $\gtrsim 100$ OAO up to $z \sim 8$. Assuming the $\Lambda$CDM model at late times, we find the 95\%~confidence level upper limit $H_0<73.2\,{\rm km}/{\rm s}/{\rm Mpc}$, in slight disagreement with a host of local $H_0$ measurements. Taken at face value, and assuming that the OAO ages are reliable, this suggests that ultimately a combination of pre- and post-recombination ($z \lesssim 10$) new physics might be required to reconcile cosmic ages with early-time and local $H_0$ measurements. In the context of the Hubble tension, our results motivate the study of either combined global pre- and post-recombination modifications to $\Lambda$CDM, or local new physics which only affects the local $H_0$ measurements.

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