Milliarcsecond compact structure of radio quasars and the geometry of the Universe

Publication date: Available online 31 January 2019Source: Physics of the Dark UniverseAuthor(s): Shuo Cao, Jingzhao Qi, Marek Biesiada, Xiaogang Zheng, Tengpeng Xu, Yu Pan, Zong-Hong ZhuAbstractIn this paper, by using the recently compiled set of 120 intermediate-luminosity quasars (ILQSO) observed in a single-frequency VLBI survey, we propose an improved model-independent method to probe cosmic curvature parameter Ωk and make the first measurement of the cosmic curvature referring to a distant past, with redshifts up to z∼3.0. Compared with other methods, the proposed one involving the quasar data achieves constraints with higher precision in this redshift range. More importantly, our results indicate that the measured Ωk is in good agreement with zero cosmic curvature, implying that there is no significant deviation from a flat Universe. Finally, we investigate the possibility of testing Ωk with a much higher accuracy using quasars observed in the future VLBI surveys. It is shown that our method could provide a reliable and tight constraint on the prior Ωk and one can expect the zero cosmic curvature to be established at the precision of ΔΩk∼10−2 with 250 well-observed radio quasars.

Source: Physics of the Dark Universe - January 31, 2019 Category: Physics Source Type: research