Context. Ultra-compact structure in radio sources (especially in quasars that can be
observed up to very high redshifts), with milliarcsecond angular sizes measured by very …

In this paper, based on a 2.29 GHz VLBI all-sky survey of 613 milliarcsecond ultra-compact
radio sources with 0.0035< z< 3.787, we describe a method of identifying the sub-sample …

As an exact result required by the Etherington reciprocity theorem, the cosmic distance
duality relation (CDDR), η (z)= DL (z)(1+ z)− 2/DA (z)= 1 plays an essential part in modern …

General relativity reproduces main current cosmological observations, assuming the validity
of the cosmic distance duality relation (CDDR) at all scales and epochs. However, CDDR is …

The cosmic distance duality (CDD) relation (based on the Etherington reciprocity theorem)
plays a crucial role in a wide assortment of cosmological measurements. Attempts at …

Two types of distance measurement are important in cosmological observations, the angular
diameter distance dA and the luminosity distance dL. In this work, we carried out an …

The cosmic distance duality relation (DDR), which connects the angular diameter distance
and luminosity distance through a simple formula DA ()(1+) 2/DL ()≡ 1, is an important …

The possibility that primordial black holes (PBHs) form a part of dark matter has been
considered over a wide mass range from the Planck mass () to the level of the supermassive …

Axion-photon mixing has been proposed as an alternative to acceleration as the explanation
for supernovae dimming. We point out that the loss of photons due to this mixing will induce …

Cosmological applications of the" redshift—angular size" test require knowledge of the
linear size of the" standard rod" used. In this paper, we study the properties of a large …