**Bulletin of Taras Shevchenko National University of Kyiv. Astronomy, no. 61, p. 20-22 (2020)**

**Impact of the statistical effects on the Hubble constant value obtained from velocities of galaxies**

**S. Parnovsky, Dr Hab.**

**Taras Shevchenko National University of Kyiv **

**Abstract**

We can obtain the Hubble constant value for the late Universe from the sample of radial velocities of galaxies and independent estimations of distances to them based on any statistical relation such as Cepheid variables, Tully-Fisher relation etc. Usually, the method of least squares is used when processing such data. However, the value of the Hubble constant is somewhat underestimated due to a statistical effect similar to the wellknown Malmquist bias. The main source of underestimation is associated with the deviation of the distances determined from the statistical dependence from their true values. The decrease of obtained Hubble constant value is about 5% for an error in the distance estimation of 20% and about 9% with an error of 30%. This impact cannot explain the recently discovered tensions between the values of Hubble constant obtained from the early and the late Universe. The estimation H_{0} = 67.4 km/s/Mpc obtained from observations in the recombination era account for about 92% of the average of the estimations based on observations of not very distant objects H_{0} = 73.3 km/s/ Mpc. Indeed, the described effect leads to underestimation of the largest of these values.

**Key words
**Hubble constant, distances to galaxies, statistical methods of data processing.

**References
**Verde, L., Treu, Т., Riess, А. 2019, Nature Astronomy, 3, 891

Parnovsky, S. L., Parnovsky, A. S. 2010, Journal of Physical Studies, 14, 3901

Parnovsky, S., Parnovsky, A. 2011, Astrophysics and Space Science, 331, 429

Parnovskyi, S. L. 2010, Visnyk Kyiv. nats. un-tu im. Tarasa Shevchenka. Astronomiia, 46, 26

Parnovsky, S. 2019, Visnyk Kyiv. nats. un-tu im. Tarasa Shevchenka. Astronomiia, 60, 46