%0 Generic %1 sedgwick2019effects %A Sedgwick, Thomas M. %A Collins, Chris A. %A Baldry, Ivan K. %A James, Philip A. %D 2019 %K tifr %T The effects of peculiar velocities in SN Ia environments on the local $H_0$ measurement %U http://arxiv.org/abs/1911.03155 %X The discrepancy between estimates of the Hubble Constant ($H_0$) measured from local ($z 0.1$) scales and from scales of the sound horizon is a crucial problem in modern cosmology. Peculiar velocities of standard candle distance indicators can systematically affect local $H_0$ measurements. We here use 2MRS galaxies to measure the local galaxy density field, finding a notable $z < 0.05$ under-density in the SGC-6dFGS region of $27 2$ %. However, no strong evidence for a 'Local Void' pertaining to the full 2MRS sky coverage is found. Galaxy densities are used to measure a density parameter, $\Delta \phi_+-$, which acts as a proxy for peculiar velocity ($v_pec$) by quantifying density gradients along a line-of-sight. $\Delta \phi_+-$ is found to correlate strongly with local $H_0$ estimates from Union 2.1 Type Ia SNe ($0.02 < z < 0.04$). Density structures on scales of $50$ Mpc are found to correlate most strongly with $H_0$ estimates in both the observational data and in mock data from the MDPL2-Galacticus simulation. Interpolating SN Ia $H_0$ estimates to their $\Delta \phi_+- = 0$ values, we can correct for the effects of density structure on the local $H_0$ estimates, even in the presence of biased peculiar velocities. For these particular observational data, we reveal a $< 0.1 \,km\,s^-1 Mpc^-1$ difference in the sample mean estimate compared to the value uncorrected for peculiar velocities. Our best estimate is then $74.9 \,km\,s^-1 Mpc^-1$. Using the mock data, the systematic uncertainty from these peculiar velocity corrections is estimated to be $0.3 \,km\,s^-1 Mpc^-1$. The dominant source of uncertainty in our estimate instead relates to Cepheid-based calibrations of distance moduli ($1.7 \,km\,s^-1 Mpc^-1$) and SN photometry ($0.7 \,km\,s^-1 Mpc^-1$).

@misc{sedgwick2019effects, abstract = {The discrepancy between estimates of the Hubble Constant ($H_{0}$) measured from local ($z \lesssim 0.1$) scales and from scales of the sound horizon is a crucial problem in modern cosmology. Peculiar velocities of standard candle distance indicators can systematically affect local $H_{0}$ measurements. We here use 2MRS galaxies to measure the local galaxy density field, finding a notable $z < 0.05$ under-density in the SGC-6dFGS region of $27 \pm 2$ %. However, no strong evidence for a 'Local Void' pertaining to the full 2MRS sky coverage is found. Galaxy densities are used to measure a density parameter, $\Delta \phi_{+-}$, which acts as a proxy for peculiar velocity ($v_{pec}$) by quantifying density gradients along a line-of-sight. $\Delta \phi_{+-}$ is found to correlate strongly with local $H_{0}$ estimates from Union 2.1 Type Ia SNe ($0.02 < z < 0.04$). Density structures on scales of $\sim 50$ Mpc are found to correlate most strongly with $H_{0}$ estimates in both the observational data and in mock data from the MDPL2-Galacticus simulation. Interpolating SN Ia $H_{0}$ estimates to their $\Delta \phi_{+-} = 0$ values, we can correct for the effects of density structure on the local $H_{0}$ estimates, even in the presence of biased peculiar velocities. For these particular observational data, we reveal a $< 0.1 \,\rm km\,s^{-1} Mpc^{-1}$ difference in the sample mean estimate compared to the value uncorrected for peculiar velocities. Our best estimate is then $74.9 \,\rm km\,s^{-1} Mpc^{-1}$. Using the mock data, the systematic uncertainty from these peculiar velocity corrections is estimated to be $0.3 \,\rm km\,s^{-1} Mpc^{-1}$. The dominant source of uncertainty in our estimate instead relates to Cepheid-based calibrations of distance moduli ($1.7 \,\rm km\,s^{-1} Mpc^{-1}$) and SN photometry ($0.7 \,\rm km\,s^{-1} Mpc^{-1}$).}, added-at = {2019-11-11T06:42:31.000+0100}, author = {Sedgwick, Thomas M. and Collins, Chris A. and Baldry, Ivan K. and James, Philip A.}, biburl = {https://www.bibsonomy.org/bibtex/2adf9fbeea20c2280d162357c1c154b01/citekhatri}, description = {The effects of peculiar velocities in SN Ia environments on the local $H_{0}$ measurement}, interhash = {1768baff6f7d144c4c790832627d7f4a}, intrahash = {adf9fbeea20c2280d162357c1c154b01}, keywords = {tifr}, note = {cite arxiv:1911.03155Comment: 15 pages, 13 figures. Submitted for publication in MNRAS}, timestamp = {2019-11-11T06:42:31.000+0100}, title = {The effects of peculiar velocities in SN Ia environments on the local $H_{0}$ measurement}, url = {http://arxiv.org/abs/1911.03155}, year = 2019 }