A Hubble diagram (HD) has recently been constructed in the redshift range
$0\lesssim z\lesssim 6.5$ using a non-linear relation between the ultraviolet and
X-ray luminosities of QSOs. The Type Ia SN HD has already provided a high-precision
test of cosmological models, but the fact that the QSO distribution extends well
beyond the supernova range ($z\lesssim 1.8$), in principle provides us with an
important complementary diagnostic whose significantly greater leverage in $z$
can impose tighter constraints on the distance versus redshift relationship. In
this paper, we therefore perform an independent test of nine different cosmological
models, among which six are expanding, while three are static. Many of these are
disfavoured by other kinds of observations (including the aforementioned Type Ia
SNe). We wish to examine whether the QSO HD confirms or rejects these earlier
conclusions. We find that four of these models (Einstein-de Sitter, the Milne
universe, the Static Universe with simple tired light and the Static universe
with plasma tired light) are excluded at the $>99\%$ C.L. The Quasi-Steady State
Model is excluded at $>95$\% C.L. The remaining four models ($\Lambda$CDM/$w$CDM,
the $R_{\rm h}=ct$ Universe, the Friedmann open universe and a Static universe
with a linear Hubble law) all pass the test. However, only $\Lambda$CDM/$w$CDM
and $R_{\rm h}=ct$ also pass the Alcock-Paczy\'nski (AP) test. The optimized
parameters in $\Lambda$CDM/$w$CDM are $\Omega _m=0.20^_$ and
$w_{de}=-1.2^_$ (the dark-energy equation-of-state). Combined
with the AP test, these values become $\Omega _m=0.38^_$ and
$w_{de}=-0.28^_$. But whereas this optimization of parameters
in $\Lambda$CDM/$w$CDM creates some tension with their concordance values,
the $R_=ct$ Universe has the advantage of fitting the QSO and AP data
without any free parameters.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/615119 |
| Date | 04 1900 |
| Creators | López-Corredoira, M., Melia, F., Lusso, E., Risaliti, G. |
| Contributors | The University of Arizona |
| Publisher | World Scientific Publishing |
| Source Sets | University of Arizona |
| Language | English |
| Detected Language | English |
| Type | Article |
| Rights | © World Scientific Publishing Company |
| Relation | http://www.worldscientific.com/doi/10.1142/S0218271816500607 |
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