The luminosity distance–redshift relation is one of the fundamental tools of modern cosmology. We compute the luminosity distance–redshift relation in a perturbed flat matter-dominated Universe, taking into account the presence of cosmological inhomogeneities up to second order in perturbation theory. Cosmological observations implementing the luminosity distance–redshift relation tell us that ...

We have tested a relative spectral lag (RSL) method suggested earlier as a luminosity/redshift (or distance) estimator, using the generalized method by Schaefer & Collazzi. We find the derivations from the luminosity/redshift-RSL (L/R-RSL) relation are comparable with the corresponding observations. Applying the luminosityRSL relation to two different GRB samples, we find that there exist no vi...

That the RR Lyrae star period – K-band luminosity relation is a promising tool as a distance indicator in the Milky Way and Local Group of Galaxies is apparent on observational and theoretical grounds in the literature. Less clear is the sensitivity of the relation, and consequently the physics of horizontal branch stars, to differences in stellar environment. In this paper, the first measureme...

Observations of type Ia supernovæ at high redshifts have become an important tool for studying the geometry of the universe. The relation between the duration of the peak phase of a type Ia supernova’s lightcurve and its luminosity (broader is brighter) forms the cornerstone of this measurement, yet it is a purely empirical relation. In this paper we show that the relation is a natural conseque...

The relationship between variability, luminosity and redshift in the South Galactic Pole QSO sample is examined in an eeort to disentangle the eeects of luminosity and redshift in the amplitude of the optical variations. The anticorrelation between variability and luminosity found by other authors is connrmed. Our analysis also supports claims that variability increases with redshift, most like...

The differing Mbh-L relations presented in McLure & Dunlop, Marconi & Hunt and Erwin et al. have been investigated. A number of issues have been identified and addressed in each of these studies, including but not limited to: the removal of a dependency on the Hubble constant; a correction for dust attenuation in the bulges of disc galaxies; the identification of lenticular galaxies previously ...

The data on dynamic masses and multicolor photometry of 56 M-type components of binary/multiple systems was collected. Critical evaluation of late type stars bolometric correction scales have been performed. Our refined and reduced data is comparedwith published empirical and theoreticalmassluminosity relations. Our data does not exclude the existence of a step-like feature at MV = 12m. The bes...

We investigate the MBH−σ∗ relation for radio-loud quasars with redshift z < 0.83 in Data Release 3 of the Sloan Digital Sky Survey (SDSS). The sample consists of 3772 quasars with better model of Hβ and [O III] lines and available radio luminosity, including 306 radio-loud quasars, 3466 radio-quiet quasars with measured radio luminosity or upper-limit of radio luminosity (181 radio-quiet quasar...

Light variation of the 47 AGB star candidates in the outer Galactic disk has been monitored at I–band for 5 years. Periods were determined well for 18 of them and less reliably for the other 25. The average period of the objects is then 500 days. According to the period–luminosity relation, the mean luminosity of the sample stars is 10000 L• ⊙. Based on the absolute luminosity derived from the ...

We reanalyze the galaxy-mass correlation function measured by the Sloan Digital Sky Survey to obtain host dark matter halo masses at galaxy and galaxy group scales. We extend the data to galaxy clusters in the 2MASS catalog and study the relation between central galaxy luminosity and halo mass. While the central galaxy luminosity scales as ∼ M0.7−0.8 at low masses, the relation flattens to ∼ M<...