Quantifying ionospheric effects on global 21-cm observations

Constraining dark matter through 21 cm observations

Beyond reionization epoch cosmic hydrogen is neutral and can be directly observed through its 21 cm line signal. If dark matter (DM) decays or annihilates the corresponding energy input affects the hydrogen kinetic temperature and ionized fraction, and contributes to the Lyα background. The changes induced by these processes on the 21 cm signal can then be used to constrain the proposed DM cand...

Prospects for Redshifted 21-cm Observations of Quasar Hii Regions

The introduction of low-frequency radio arrays over the coming decade is expected to revolutionize the study of the reionization epoch. Observation of the contrast in redshifted 21cm emission between a large H II region and the surrounding neutral IGM will be the simplest and most easily interpreted signature. We assess the sensitivity of three generations of planned low-frequency arrays to qua...

Deep Observations with the Parkes 21-cm Multibeam System

We report on a preliminary analysis of a 5600 sec per point survey of 32 square degrees in Centaurus, carried out with the Parkes 13-beam system. The signal-to-noise ratio is found to improve as √ tobs for the whole integration. We have detected 102 HI sources between +250 and +12,700 km s−1 either by eye or by using the new galaxy-finding algorithm PICASSO. Over half of these are new HI detect...

Global 21 cm signal experiments : A designer ’ s guide

21-cm Synthesis Observations of Virgohi 21 - a Possible Dark Galaxy in the Virgo Cluster

Many observations indicate that dark matter dominates the extra-galactic Universe, yet no totally dark structure of galactic proportions has ever been convincingly identified. Previously we have suggested that VIRGOHI 21, a 21-cm source we found in the Virgo Cluster using Jodrell Bank, was a possible dark galaxy because of its broad line-width (∼ 200 km s−1) unaccompanied by any visible gravita...