%0 Generic %1 vagnozzi2021implications %A Vagnozzi, Sunny %A Pacucci, Fabio %A Loeb, Abraham %D 2021 %K tifr %T Implications for the Hubble tension from the ages of the oldest astrophysical objects %U http://arxiv.org/abs/2105.10421 %X We use the ages of old astrophysical objects (OAO) in the redshift range $0 z 8$ 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 $100$ OAO up to $z 8$. Assuming the $Łambda$CDM model at late times, we find the 95\%~confidence level upper limit $H_0<73.2\,km/s/Mpc$, 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 ($z 10$) 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 $Łambda$CDM, or local new physics which only affects the local $H_0$ measurements.

@misc{vagnozzi2021implications, abstract = {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.}, added-at = {2021-05-24T08:24:35.000+0200}, author = {Vagnozzi, Sunny and Pacucci, Fabio and Loeb, Abraham}, biburl = {https://www.bibsonomy.org/bibtex/27977bb83650ef25cf9d582704ed2a3d3/citekhatri}, description = {Implications for the Hubble tension from the ages of the oldest astrophysical objects}, interhash = {791f27203669cf7248fb6404a4c94236}, intrahash = {7977bb83650ef25cf9d582704ed2a3d3}, keywords = {tifr}, note = {cite arxiv:2105.10421Comment: 7 pages, 2 figures}, timestamp = {2021-05-24T08:24:35.000+0200}, title = {Implications for the Hubble tension from the ages of the oldest astrophysical objects}, url = {http://arxiv.org/abs/2105.10421}, year = 2021 }