Page 66 - analysis-and-interpretation-of-astronomical-sp

Analysis and Interpretation of Astronomical Spectra 66

without cosmological model parameters [431]. Here, therefore the -value has become es-
tablished, which can be measured directly in the spectrum (sect, 15.3 {17}) and remains
independent of the debated cosmological models. Therefore, the classical approach, to de-
termine the distance by the proportional Hubble law , remains restricted on the relative

"near vicinity" and is eg still applicable in the field of the Messier galaxies.

15.9 The Apparent Dilemma at

The range of the observed -values reaches today (2013) up to the Galaxy Abell 1835 with

. This was discovered in 2004 mainly by a French/Swiss team of researchers, with

the VLT of the ESO Southern Observatory! Anyway for values , applied in formulas

or , , at least an apparent dilemma shows up, because the radial velocity

, respectively the expansion of spacetime, seems to surpass the speed of light . In the

past, as a way out, sometimes the relativistic Doppler formula {20}, chap. 15.4, was pro-
posed. This procedure in fact prevents the exceeding of , but is nowadays no more ac-

cepted by most of the experts. So, for instance in the CDS database [100], the former rela-
tivistic - value for the quasar 3C273, still calculated on the basis of the STR , has re-

cently been deleted. However, the "classical" radial velocity, based on , is still to

find in this data set (2013).

Due to the increasing expansion of the space-time-lattice, at such extreme distances not
only the classical term for "distance" gets obviously senseless. This applies also to the
"classical" calculation of the apparent radial velocity by the Doppler principle, without
any consideration of cosmological models [431]. Accepted today, but still debated, are dif-
ferent cosmological models – most of them based on the General Theory of Relativity GTR.

15.10 Radial Velocity- and Cosmological Spacetime Expansion at Messier-Galaxies

The table on the following page shows, sorted by increasing distance , the measured he-
liocentric radial velocities for 38 Messier galaxies, according to NED NASA Extragalactic
Database [101]. The cosmological related spacetime expansion . is calculated accord-

ing to with distance values from CDS [100]. Positive values = red-shifted, negative val-
ues = blue-shifted. These figures clearly indicate, that in this “immediate neighbourhood”,
the kinematic peculiar motion of the galaxies still dominates. Nevertheless, at distances
about more than 50 million ly, the trend becomes already evident, that the measured radial
velocities tend, with increasing distance, more and more to the theoretical/cosmological
speed of the spacetime expansion . Anyhow in more than 50M ly distance still two gal-

axies can be found (M86 and M98) with relatively strong negative values (blue coloured
rows). This behaviour show 6 of 38, or about 16% of the Messier Galaxies. Most distant
galaxy is M109 with about 81M ly.

Based on the measured radial velocities , in the following table also the corresponding -

values can be found, calculated with formula . These modest amounts show

very impressively – as seen in the cosmic scale – how extremely small this area really is.