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| Main Authors: | , , , , , , , , , , , , |
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| Format: | Preprint |
| Published: |
2026
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2604.07441 |
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| _version_ | 1866915924235255808 |
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| author | Chung, Chul Lee, Young-Wook Yoon, Suk-Jin Kim, Yong -Cheol Han, Sang-Il Cho, Hyejeon Lim, Dongwook Kim, Young-Lo Jang, Sohee Hong, Seungsoo Park, Seunghyun Son, Junhyuk Lee, Myung Gyoon |
| author_facet | Chung, Chul Lee, Young-Wook Yoon, Suk-Jin Kim, Yong -Cheol Han, Sang-Il Cho, Hyejeon Lim, Dongwook Kim, Young-Lo Jang, Sohee Hong, Seungsoo Park, Seunghyun Son, Junhyuk Lee, Myung Gyoon |
| contents | The tip of the red giant branch (TRGB) provides a key standard candle for extragalactic distance measurements and for refining the Hubble constant. We test its robustness by quantifying how metallicity, $α$-element enhancement, age, and initial helium abundance modulate the TRGB luminosity, using synthetic composite color--magnitude diagrams in the $I$ and $F814W$ bands. We find that metallicity and $α$-element enhancement are the primary drivers of TRGB variation, while age introduces only a modest effect and helium abundance is negligible. At fixed age and helium content, increasing the mean metallicity by 0.5 dex or the $α$-element enhancement by 0.3 dex produces the well-known systematic dimming of 0.046 and 0.050 mag, respectively, in $M_I^{\rm TRGB}$, and of 0.093 and 0.044 mag, respectively, in $M_{F814W}^{\rm TRGB}$. By comparison, changes in age of 3~Gyr and in initial helium abundance of 0.10 yield minor luminosity shifts, with average changes of 0.031 and 0.009~mag, respectively, in $M_I^{\rm TRGB}$, and of 0.035 and 0.027 mag, respectively, in $M_{F814W}^{\rm TRGB}$, substantially smaller than those caused by variations in metallicity or $α$-element enhancement. For mixed stellar populations under typical stellar-halo metallicity conditions, the net variation in $M_I^{\rm TRGB}$ arising from each combination of the $α$-element enhancement, age, and initial helium abundance remains below 0.028~mag, well within reported systematic uncertainties. Together, these results reaffirm the TRGB as a highly robust distance indicator and support its continued use as an independent anchor for precision cosmology in the era of the Hubble-tension debate. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2604_07441 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | How Robust is the Cosmic Distance with Tip of Red Giant Branch against Stellar Population Variations? Chung, Chul Lee, Young-Wook Yoon, Suk-Jin Kim, Yong -Cheol Han, Sang-Il Cho, Hyejeon Lim, Dongwook Kim, Young-Lo Jang, Sohee Hong, Seungsoo Park, Seunghyun Son, Junhyuk Lee, Myung Gyoon Astrophysics of Galaxies The tip of the red giant branch (TRGB) provides a key standard candle for extragalactic distance measurements and for refining the Hubble constant. We test its robustness by quantifying how metallicity, $α$-element enhancement, age, and initial helium abundance modulate the TRGB luminosity, using synthetic composite color--magnitude diagrams in the $I$ and $F814W$ bands. We find that metallicity and $α$-element enhancement are the primary drivers of TRGB variation, while age introduces only a modest effect and helium abundance is negligible. At fixed age and helium content, increasing the mean metallicity by 0.5 dex or the $α$-element enhancement by 0.3 dex produces the well-known systematic dimming of 0.046 and 0.050 mag, respectively, in $M_I^{\rm TRGB}$, and of 0.093 and 0.044 mag, respectively, in $M_{F814W}^{\rm TRGB}$. By comparison, changes in age of 3~Gyr and in initial helium abundance of 0.10 yield minor luminosity shifts, with average changes of 0.031 and 0.009~mag, respectively, in $M_I^{\rm TRGB}$, and of 0.035 and 0.027 mag, respectively, in $M_{F814W}^{\rm TRGB}$, substantially smaller than those caused by variations in metallicity or $α$-element enhancement. For mixed stellar populations under typical stellar-halo metallicity conditions, the net variation in $M_I^{\rm TRGB}$ arising from each combination of the $α$-element enhancement, age, and initial helium abundance remains below 0.028~mag, well within reported systematic uncertainties. Together, these results reaffirm the TRGB as a highly robust distance indicator and support its continued use as an independent anchor for precision cosmology in the era of the Hubble-tension debate. |
| title | How Robust is the Cosmic Distance with Tip of Red Giant Branch against Stellar Population Variations? |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2604.07441 |