Bias of the Hubble constant value caused by errors in galactic distance indicators. (arXiv:2109.09645v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Parnovsky_S/0/1/0/all/0/1">S.L.Parnovsky</a>
The bias in the determination of the Hubble parameter and the Hubble constant
in the modern Universe is discussed. It could appear due to statistical
processing of data on galaxies redshifts and estimated distances based on some
statistical relations with limited accuracy. This causes a number of effects
leading to either underestimation or overestimation of the Hubble parameter
when using any methods of statistical processing, primarily the least squares
method (LSM). The value of the Hubble constant is underestimated when
processing a whole sample; when the sample is constrained by distance,
especially when constrained from above, it is significantly overestimated due
to data selection. The bias significantly exceeds the values of the error the
Hubble constant calculated by the LSM formulae.
These effects are demonstrated both analytically and using Monte Carlo
simulations, which introduce deviations in both velocities and estimated
distances to the original dataset described by the Hubble law. The
characteristics of the deviations are similar to real observations. Errors in
estimated distances are up to 20%. They lead to the fact that when processing
the same mock sample using LSM, it is possible to obtain an estimate of the
Hubble constant from 96% of the true value when processing the entire sample to
110% when processing the subsample with distances limited from above.
The impact of these effects can lead to a bias in the Hubble constant
obtained from real data and an overestimation of the accuracy of determining
this value. This may call into question the accuracy of determining the Hubble
constant and significantly reduce the tension between the values obtained from
the observations in the early and modern Universe, which were actively
discussed during the last year.
The bias in the determination of the Hubble parameter and the Hubble constant
in the modern Universe is discussed. It could appear due to statistical
processing of data on galaxies redshifts and estimated distances based on some
statistical relations with limited accuracy. This causes a number of effects
leading to either underestimation or overestimation of the Hubble parameter
when using any methods of statistical processing, primarily the least squares
method (LSM). The value of the Hubble constant is underestimated when
processing a whole sample; when the sample is constrained by distance,
especially when constrained from above, it is significantly overestimated due
to data selection. The bias significantly exceeds the values of the error the
Hubble constant calculated by the LSM formulae.
These effects are demonstrated both analytically and using Monte Carlo
simulations, which introduce deviations in both velocities and estimated
distances to the original dataset described by the Hubble law. The
characteristics of the deviations are similar to real observations. Errors in
estimated distances are up to 20%. They lead to the fact that when processing
the same mock sample using LSM, it is possible to obtain an estimate of the
Hubble constant from 96% of the true value when processing the entire sample to
110% when processing the subsample with distances limited from above.
The impact of these effects can lead to a bias in the Hubble constant
obtained from real data and an overestimation of the accuracy of determining
this value. This may call into question the accuracy of determining the Hubble
constant and significantly reduce the tension between the values obtained from
the observations in the early and modern Universe, which were actively
discussed during the last year.
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