分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： We use a combination of observational data in order to reconstruct the free function of f(T) gravity in a model-independent manner. Starting from the data-driven determined dark-energy equation-of-state parameter we are able to reconstruct the f(T) form. The obtained function is consistent with the standard {\Lambda}CDM cosmology within 1{\sigma} confidence level, however the best-fit value experiences oscillatory features. We parametrise it with a sinusoidal function with only one extra parameter comparing to {\Lambda}CDM paradigm, which is a small oscillatory deviation from it, close to the best-fit curve, and inside the 1{\sigma} reconstructed region. Similar oscillatory dark-energy scenarios are known to be in good agreement with observational data, nevertheless this is the first time that such a behavior is proposed for f(T) gravity. Finally, since the reconstruction procedure is completely model-independent, the obtained data-driven reconstructed f(T) form could release the tensions between {\Lambda}CDM estimations and local measurements, such as the H0 and {\sigma}8 ones.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Tidal disruption events (TDEs), apart from producing luminous electromagnetic (EM) flares, can generate potentially detectable gravitational wave (GW) burst signals by future space-borne GW detectors. In this Letter, we propose a methodology to constrain the Hubble constant $H_0$ by incorporating the TDE parameters measured by EM observations (e.g., stellar mass, black hole (BH) mass and spin, and other orbital parameters) into the observed TDE GW waveforms. We argue that an accurate knowledge of the BH spin could help constrain the orbital inclination angle, hence alleviating the well-known distance-inclination degeneracy in GW waveform fitting. For individual TDEs, the precise redshift measurement of the host galaxies along with the luminosity distance $D_{\rm L}$ constrained by EM and GW signals would give a self-contained measurement of $H_0$ via Hubble's law, completely independent of any specific cosmological models.
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