Reassessing the Constraints from SH0ES Extragalactic Cepheid Amplitudes on Systematic Blending Bias
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2023
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| _version_ | 1866929246829543424 |
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| author | Sharon, Amir Kushnir, Doron Yuan, Wenlong Macri, Lucas Riess, Adam |
| author_facet | Sharon, Amir Kushnir, Doron Yuan, Wenlong Macri, Lucas Riess, Adam |
| contents | The SH0ES collaboration Hubble constant determination is in a ${\sim}5σ$ 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. (R20) compared the light curves amplitudes of extragalactic and MW Cepheids to constrain an unaccounted systematic blending bias, $γ=-0.029\pm0.037\,\rm{mag}$, which cannot explain the required, $γ=0.24\pm0.05\,\rm{mag}$, to resolve the Hubble tension. Further checks by Riess et al. 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 ${\approx}0.04\,\rm{mag}$ uncertainty in determining $γ$, not included by R20. While our final estimate, $γ=0.013\pm0.057\,\rm{mag}$, is consistent with the value derived by R20 and is consistent with no bias, the error is somewhat larger, and the best fitting value is shifted by ${\approx}0.04\,\rm{mag}$ and closer to zero. Future observations, especially with JWST, would allow better calibration of $γ$. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2305_14435 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Reassessing the Constraints from SH0ES Extragalactic Cepheid Amplitudes on Systematic Blending Bias Sharon, Amir Kushnir, Doron Yuan, Wenlong Macri, Lucas Riess, Adam Cosmology and Nongalactic Astrophysics Astrophysics of Galaxies Solar and Stellar Astrophysics The SH0ES collaboration Hubble constant determination is in a ${\sim}5σ$ 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. (R20) compared the light curves amplitudes of extragalactic and MW Cepheids to constrain an unaccounted systematic blending bias, $γ=-0.029\pm0.037\,\rm{mag}$, which cannot explain the required, $γ=0.24\pm0.05\,\rm{mag}$, to resolve the Hubble tension. Further checks by Riess et al. 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 ${\approx}0.04\,\rm{mag}$ uncertainty in determining $γ$, not included by R20. While our final estimate, $γ=0.013\pm0.057\,\rm{mag}$, is consistent with the value derived by R20 and is consistent with no bias, the error is somewhat larger, and the best fitting value is shifted by ${\approx}0.04\,\rm{mag}$ and closer to zero. Future observations, especially with JWST, would allow better calibration of $γ$. |
| title | Reassessing the Constraints from SH0ES Extragalactic Cepheid Amplitudes on Systematic Blending Bias |
| topic | Cosmology and Nongalactic Astrophysics Astrophysics of Galaxies Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2305.14435 |