English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We pay particular attention to the high end of the $\lya$ optical depthdistribution of a quasar spectrum. Based on the flux distribution(Miralda-Escud\'e et al 1996), a simple yet seemingly cosmological model-differentiating statistic, $\Delta_{\tau_0}$ -- the cumulative probability ofa quasar spectrum with $\lya$ optical depth greater than a high value $\tau_0$-- is emphasized. It is shown that two different models -- the cold dark mattermodel with a cosmological constant and the mixed hot and cold dark mattermodel, both normalized to COBE and local galaxy cluster abundance -- yieldquite different values of $\Delta_{\tau_0}$: 0.13 of the former versus 0.058 ofthe latter for $\tau_0=3.0$ at $z=3$. Moreover, it is argued that$\Delta_{\tau_0}$ may be fairly robust to compute theoretically because it doesnot seem to depend sensitively on small variations of simulations parameterssuch as radiation field, cooling, feedback process, radiative transfer,resolution and simulation volume within the plausible ranges of the concernedquantities. Furthermore, it is illustrated that $\Delta_{\tau_0}$ can beobtained sufficiently accurately from currently available observed quasarspectra for $\tau_0\sim 3.0-4.0$, when observational noise is properly takeninto account. We anticipate that analyses of observations of quasar $\lya$absorption spectra over a range of redshift may be able to constrain theredshift evolution of the amplitude of the density fluctuations onsmall-to-intermediate scales, therefore providing an independent constraint on$\Omega_0$, $\Omega_{0,HDM}$ and $\Lambda_0$.Comment: ApJ Letters, in press, substantial changes have been made from the  last versio

Testing Cosmological Models with a L[CLC]y[/CLC]α Forest Statistic: The High End of the Optical Depth Distribution