%0 Generic %1 colgain2019recasting %A Colgáin, Eoin Ó %D 2019 %K %T Recasting $H_0$ tension as $Ømega_m$ tension at low $z$ %U http://arxiv.org/abs/1903.11743 %X Inspired by the recent observation that local measurements of the Hubble constant $H_0$ and the Planck CMB value based on $Łambda$CDM show a discrepancy at $4.4 \, \sigma$ Riess:2019cxk, we study $Łambda$CDM at low redshift. Concretely, we expand $Łambda$CDM perturbatively at small $z$ and perform a two-parameter fit of the distance modulus to Pantheon data for a running cut-off $z_max 0.3$. Moving beyond the Hubble constant $H_0$, we shift focus to matter density $Ømega_m$, noting foremost that its best-fit value is sensitive to the cut-off. For $z_max > 0.1$, the uncertainties in $Ømega_m$ decrease and the difference with the Planck value $Ømega_m = 0.315 0.007$ becomes noticeable. In particular, in the range $0.1 z_max < 0.16$, the best-fit value is negative and the discrepancy with the Planck value approaches $4 \, \sigma$. Restricting to $z_max$ where the best-fit value is positive and physical, the discrepancy is reduced to $3.1 \, \sigma$. For high-energy theorists, the analysis appears to support the de Sitter Swampland conjecture.

@misc{colgain2019recasting, abstract = {Inspired by the recent observation that local measurements of the Hubble constant $H_0$ and the Planck CMB value based on $\Lambda$CDM show a discrepancy at $4.4 \, \sigma$ \cite{Riess:2019cxk}, we study $\Lambda$CDM at low redshift. Concretely, we expand $\Lambda$CDM perturbatively at small $z$ and perform a two-parameter fit of the distance modulus to Pantheon data for a running cut-off $z_{\textrm{max}} \leq 0.3$. Moving beyond the Hubble constant $H_0$, we shift focus to matter density $\Omega_m$, noting foremost that its best-fit value is sensitive to the cut-off. For $z_{\textrm{max}} > 0.1$, the uncertainties in $\Omega_m$ decrease and the difference with the Planck value $\Omega_m = 0.315 \pm 0.007$ becomes noticeable. In particular, in the range $0.1 \leq z_{\textrm{max}} < 0.16$, the best-fit value is negative and the discrepancy with the Planck value approaches $4 \, \sigma$. Restricting to $z_{\textrm{max}}$ where the best-fit value is positive and physical, the discrepancy is reduced to $3.1 \, \sigma$. For high-energy theorists, the analysis appears to support the de Sitter Swampland conjecture.}, added-at = {2019-03-29T06:34:39.000+0100}, author = {Colgáin, Eoin Ó}, biburl = {https://www.bibsonomy.org/bibtex/2ab72ffe5eb40d006ce5f7cd993749111/gpkulkarni}, interhash = {743a913df860a4ee374cd24ed1ef0efd}, intrahash = {ab72ffe5eb40d006ce5f7cd993749111}, keywords = {}, note = {cite arxiv:1903.11743Comment: 9 pages, my first foray into astro-ph, feedback welcome}, timestamp = {2019-03-29T06:34:39.000+0100}, title = {Recasting $H_0$ tension as $\Omega_m$ tension at low $z$}, url = {http://arxiv.org/abs/1903.11743}, year = 2019 }