Probing dark energy with baryonic oscillations and future radio surveys of neutral Hydrogen

F. B. Abdalla; S. Rawlings

doi:10.1111/j.1365-2966.2005.08650.x

paper

Probing dark energy with baryonic oscillations and future radio surveys of neutral Hydrogen

arXiv:astro-ph/0411342 · doi:10.1111/j.1365-2966.2005.08650.x

Abstract

Current surveys may be on the verge of measuring the baryonic oscillations in the galaxy power spectrum which are clearly seen imprinted on the Cosmic Microwave Background. It has recently been proposed that these oscillations allow a `standard ruler' method of probing the equation of state of dark energy. In this paper we present a new calculation of the number of galaxies future adio telescopes will detect in surveys of the sky in neutral Hydrogen (HI). We estimate the likely statistical errors if the standard ruler method were to be applied to such surveys. We emphasise uncertainties in our calculations, and pinpoint the most important features of future HI surveys if they are to provide new constraints on dark energy via baryonic oscillations. Designs of future radio telescopes are required to have a large bandwidth (characterised by β $, t h er a t i oo f t h e in s t an t an eo u s ban d w i d t h t o t h e ban d w i d t h r e q u i r e d b y s u r v ey) an d t o ha v e t h e w i d es t in s t an t an eo u s (1.4 G H z) f i e l d o f v i e w ($ FOV $) p oss ib l e . G i v e n t h ee x p ec t e d se n s i t i v i t y o f a f u t u r e S q u a r eK i l o m e t r e A r r a y (S K A), g i v e n t ha t ha l f o f i t sco l l ec t in g a r e a w i l l b eco n ce n t r a t e d ina cor eo f d iam e t er$ \sim 5 ~ \rm km $, an d g i v e na r e a so nab l es u r v ey d u r a t i o n ($ T_0\sim $1 y r), w es h o w t ha tt h er e w i l l b e n e g l i g ib l es h o t n o i seo na p o w er s p ec t r u m d er i v e df r o m H I g a l a x i eso u tt or e d s hi f t$ z \simeq 1.5 $. T o a ccess t h e l a r g es t cos mi c v o l u m e p oss ib l e b y s u r v ey in g a l l t h es k y a v ai l ab l e, w e a r g u e t ha t$ β $,$ T_0 $an d$ FOV $m u s t o b ey t h er e l a t i o n$ βFOV T_0 \gtsimeq 10 \rm deg^2 $y r . A n$ \sim $1 - y r S K A s u r v ey w o u l d t h e n co n t ain$ \gtsimeq 10^{9} (f_{\rm sky}/0.5) $H I g a l a x i es an d p r o v i d eco n s t r ain t so n t h e d a r k - e n er g y p a r am e t er$ w $o f or d er$ Δw \simeq 0.01 (f_{\rm sky}/0.5)^{-0.5}$.

15 pages, submitted to MNRAS

Probing dark energy with baryonic oscillations and future radio surveys of neutral Hydrogen

Abstract

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