A Transit Search for Highly Redshifted HI
Abstract
An experiment to detect protoclusters at high redshift is described. We attempt to observe these objects in the 1420 MHz line from neutral atomic hydrogen in the redshift range 4.7 <= z <= 5.5 (219 <= nu <= 251 MHz). The expected signal strength is very weak so we need a large aperture and a long integration time for a detection to be feasible. This is achieved by building a dedicated and specialized instrument, which allows the experiment to run continuously, in the background, at the Arecibo radio-telescope. We scan the same declination strip each day and co-add the data from successive sidereal days to achieve long integration times. The search volume is 1.8 times10^8 h^{-3} Mpc^3 and the beamwidth is about 0.75^circ, corresponding to a drift time of about three minutes. Strong time-variable RFI is a serious problem in the search band. We continue to gather more data but so far we have failed to detect a protocluster.
- Publication:
-
Highly Redshifted Radio Lines
- Pub Date:
- 1999
- Bibcode:
- 1999ASPC..156...34W
- Keywords:
-
- RADIO ASTRONOMY;
- COSMOLOGY;
- GALAXIES: FORMATION OF;
- RADIO LINES: 21 CM;
- UNIVERSE: STRUCTURE OF;
- INTERGALACTIC MEDIUM