%0 Generic %1 sharon2023reassessing %A Sharon, Amir %A Kushnir, Doron %A Yuan, Wenlong %A Macri, Lucas %A Riess, Adam %D 2023 %K tifr %T Reassessing the Constraints from SH0ES Extragalactic Cepheid Amplitudes on Systematic Blending Bias %U http://arxiv.org/abs/2305.14435 %X The SH0ES collaboration Hubble constant determination is in a $\sim5\sigma$ difference with the Planck value, known as the Hubble tension. The accuracy of the Hubble constant measured with extragalactic Cepheids depends on robust stellar-crowding background estimation. Riess et al. 2020 (R20) compared the light curves amplitudes of extragalactic and MW Cepheids to constrain an unaccounted systematic blending bias, $\gamma=-0.029\pm0.037\,mag$, which cannot explain the required, $\gamma=0.24\pm0.05\,mag$, to resolve the Hubble tension. Further checks by Riess et al. 2022 demonstrate that a possible blending is not likely related to the size of the crowding correction. We repeat the R20 analysis, with the following main differences: 1. We limit the extragalactic and MW Cepheids comparison to periods $Płesssim50\,d$, since the number of MW Cepheids with longer periods is minimal; 2. We use publicly available data to recalibrate amplitude ratios of MW Cepheids in standard passbands; 3. We remeasure the amplitudes of Cepheids in NGC 5584 and NGC 4258 in two HST filters (F555W and F350LP) to improve the empirical constraint on their amplitude ratio $A^555/A^350$. We show that the filter transformations introduce an $\approx0.04\,mag$ uncertainty in determining $\gamma$, not included by R20. While our final estimate, $\gamma=0.013\pm0.057\,mag$, is consistent with the value derived by R20, the error is somewhat larger, and the best-fit value is shifted by $\approx0.04\,mag$. Although the obtained $\gamma$ for this crowding test is consistent with zero, folding (in quadratures) it is $\approx3.0\sigma$ away from aligning with Planck. Future observations, especially with JWST, would allow better calibration of $\gamma$.

@misc{sharon2023reassessing, abstract = {The SH0ES collaboration Hubble constant determination is in a $\mathord{\sim}5\sigma$ difference with the \textit{Planck} value, known as the Hubble tension. The accuracy of the Hubble constant measured with extragalactic Cepheids depends on robust stellar-crowding background estimation. Riess et al. 2020 (R20) compared the light curves amplitudes of extragalactic and MW Cepheids to constrain an unaccounted systematic blending bias, $\gamma=-0.029\pm0.037\,\rm{mag}$, which cannot explain the required, $\gamma=0.24\pm0.05\,\rm{mag}$, to resolve the Hubble tension. Further checks by Riess et al. 2022 demonstrate that a possible blending is not likely related to the size of the crowding correction. We repeat the R20 analysis, with the following main differences: 1. We limit the extragalactic and MW Cepheids comparison to periods $P\lesssim50\,\rm{d}$, since the number of MW Cepheids with longer periods is minimal; 2. We use publicly available data to recalibrate amplitude ratios of MW Cepheids in standard passbands; 3. We remeasure the amplitudes of Cepheids in NGC 5584 and NGC 4258 in two HST filters (F555W and F350LP) to improve the empirical constraint on their amplitude ratio $A^{555}/A^{350}$. We show that the filter transformations introduce an $\mathord{\approx}0.04\,\rm{mag}$ uncertainty in determining $\gamma$, not included by R20. While our final estimate, $\gamma=0.013\pm0.057\,\rm{mag}$, is consistent with the value derived by R20, the error is somewhat larger, and the best-fit value is shifted by $\mathord{\approx}0.04\,\rm{mag}$. Although the obtained $\gamma$ for this crowding test is consistent with zero, folding (in quadratures) it is $\mathord{\approx}3.0\sigma$ away from aligning with \textit{Planck}. Future observations, especially with JWST, would allow better calibration of $\gamma$.}, added-at = {2023-05-25T07:26:09.000+0200}, author = {Sharon, Amir and Kushnir, Doron and Yuan, Wenlong and Macri, Lucas and Riess, Adam}, biburl = {https://www.bibsonomy.org/bibtex/2c1c41bd1516540496c705fd9cc5bae66/citekhatri}, description = {Reassessing the Constraints from SH0ES Extragalactic Cepheid Amplitudes on Systematic Blending Bias}, interhash = {6939f28be8632842773e72aecef2fce3}, intrahash = {c1c41bd1516540496c705fd9cc5bae66}, keywords = {tifr}, note = {cite arxiv:2305.14435Comment: 20 pages, 12 figures. Submitted to MNRAS}, timestamp = {2023-05-25T07:26:09.000+0200}, title = {Reassessing the Constraints from SH0ES Extragalactic Cepheid Amplitudes on Systematic Blending Bias}, url = {http://arxiv.org/abs/2305.14435}, year = 2023 }