The Accuracy of the Hubble Constant Measurement Verified through Cepheid Amplitudes
| Autor: | Daniel Scolnic, Adam G. Riess, Stefano Casertano, Wenlong Yuan, Lucas M. Macri |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
Cosmology and Nongalactic Astrophysics (astro-ph.CO)
010504 meteorology & atmospheric sciences Cepheid variable Milky Way FOS: Physical sciences Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics 01 natural sciences Photometry (optics) symbols.namesake 0103 physical sciences Astrophysics::Solar and Stellar Astrophysics 010303 astronomy & astrophysics Solar and Stellar Astrophysics (astro-ph.SR) Astrophysics::Galaxy Astrophysics 0105 earth and related environmental sciences Physics Astronomy and Astrophysics Light curve Crowding Astrophysics - Astrophysics of Galaxies Amplitude Astrophysics - Solar and Stellar Astrophysics Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) symbols Hubble's law Free parameter Astrophysics - Cosmology and Nongalactic Astrophysics |
| Popis: | The accuracy of the Hubble constant measured with extragalactic Cepheids depends on robust photometry and background estimation in the presence of stellar crowding. The conventional approach accounts for crowding by sampling backgrounds near Cepheids and assuming they match those at their positions. We show a direct consequence of crowding by unresolved sources at Cepheid sites is a reduction in the fractional amplitudes of their light curves. We use a simple analytical expression to infer crowding directly from the light curve amplitudes of >200 Cepheids in 3 SNe~Ia hosts and NGC 4258 as observed by HST -- the first near-infrared amplitudes measured beyond the Magellanic Clouds. Where local crowding is minimal, we find near-infrared amplitudes match Milky Way Cepheids at the same periods. At greater stellar densities we find that the empirically measured amplitudes match the values predicted (with no free parameters) from crowding assessed in the conventional way from local regions, confirming their accuracy for estimating the background at the Cepheid locations. Extragalactic Cepheid amplitudes would need to be ~20% smaller than measured to indicate additional, unrecognized crowding as a primary source of the present discrepancy in H_0. Rather we find the amplitude data constrains a systematic mis-estimate of Cepheid backgrounds to be 0.029 +/- 0.037 mag, more than 5x smaller than the size of the present ~0.2 mag tension in H_0. We conclude that systematic errors in Cepheid backgrounds do not provide a plausible resolution to the Hubble tension. submitted to ApJ, comments welcome, 25 pages, 7 figures |
| Databáze: | OpenAIRE |
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