arXiv subjects

Ron Ekers

Publications and source records attributed to Ron Ekers.

20 records · Page 2Linked to original sources

arXiv2005

CO(1-0) & CO(5-4) observations of the most distant known radio galaxy at z=5.2

Using the Australia Telescope Compact Array we have detected CO(1-0) and CO(5-4) from TNJ0924-2201 at z=5.2, the most distant radio galaxy known to date. This is the second highest redshift detection of CO published so far. The CO(1-0) is 250-400 km/sec wide with a peak flux density of 520 +- 115 microJy/beam whilst the CO(5-4) line emission is 200-300 km/sec wide with a peak flux density of 7.8 +- 2.7 mJy/beam. Both transitions are spatially unresolved but there is marginal evidence for spatial offsets between the CO and the host galaxy; the CO(1-0) is located 28 +- 11 kpc (4.5 +- 1.7 arcsec) north of the radio galaxy whilst the CO(5-4) is located 18 +- 8 kpc (2.8 +- 1.2 arcsec) south of the radio galaxy. Higher spatial resolution observations are required to determine the reality of these offsets. Our result is the second detection of CO in a high redshift galaxy without pre-selection based on a massive dust content.

astro-ph↗

arXiv1998

Cosmological Halos: A Search for the Ionized Intergalactic Medium

Standard big bang nucleosynthesis predicts the average baryon density of the Universe to be a few percent of the critical density. Only about one tenth of the predicted baryons have been seen. A plausible respository for the missing baryons is in a diffuse ionized intergalactic medium (IGM). In an attempt to measure the IGM we searched for Thomson-scattered halos around strong high redshift radio sources. Observations of the radio source 1935-692 were made with the Australia Telescope Compact Array. We assumed a uniform IGM, and isotropic steady emission of 1935-692 for a duration between 10^7 - 10^8 years. A model of the expected halo visibility function was used in χ^2 fits to place upper limits on Ω_{IGM}. The upper limits varied depending on the methods used to characterize systematic errors in the data. The results are 2/sigma limits of Ω_{IGM} < 0.65. While not yet at the sensitivity level to test primordial nucleosynthesis, improvements on the technique will probably allow this in future studies.

astro-ph↗