ACTA

Dark Energy Constraintsfrom Quasar Observations

B. Czerny^a, M.L. Martínez-Aldama^a, G. Wojtkowska^b, M. Zajaček^a, P. Marziani^c, D. Dultzin^d, M.H. Naddaf^a, S. Panda^a, R. Prince^a, R. Przyluski^e, M. Ralowski^f, M. Śniegowska^a
^aCenter for Theoretical Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
^bWarsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warszawa, Poland
^cINAF, Osservatorio Astronomico di Padova, Italy
^dInstituto de Astronomía, UNAM, Mexico
^eSpace Research Centre, Polish Academy of Sciences, Bartycka 18a, 00-716 Warsaw, Poland
^fAstronomical Observatory of the Jagiellonian University, Orla 171, 30-001 Krakow, Poland

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Recent measurements of the parameters of the concordance cosmology model (ΛCDM) done in the low-redshift Universe with supernovae Ia/Cepheids, and in the distant Universe done with cosmic microwave background imply different values for the Hubble constant (67.4±0.5 km/(s Mpc) from Planck vs. 74.03±1.42 km/(s Mpc) Riess et al. 2019). This Hubble constant tension implies that either the systematic errors are underestimated, or the ΛCDM does not represent well the observed expansion of the Universe. Since quasars - active galactic nuclei - can be observed in the nearby Universe up to redshift z~7.5, they are suitable to estimate the cosmological properties in a large redshift range. Our group develops two methods based on the observations of quasars in the late Universe up to redshift z~4.5, with the objective to determine the expansion rate of the Universe. These methods do not yet provide an independent measurement of the Hubble constant since they do not have firm absolute calibration but they allow to test the ΛCDM model, and so far no departures from this model were found.

DOI:10.12693/APhysPolA.139.389
topics: cosmology, dark energy, quasars