RHINO: a large horn antenna for detecting the 21 cm global signal

RHINO, a novel experiment at Jodrell Bank Observatory, introduces a large horn antenna designed to detect the faint 21 cm global signal from neutral hydrogen, a critical probe of the intergalactic medium's thermal state during Cosmic Dawn and Reionization. The signal, measuring tens to hundreds of millikelvin, is spectrally smooth but challenging to isolate due to foreground radio emissions and instrumental noise. RHINO leverages the high characterizability and environmental shielding of horn antennas, alongside a continuous wave calibration source to monitor gain fluctuations without rapid switching. Initial simulations demonstrate its potential for recovering physical signal parameters despite bandwidth limitations. A scaled-down prototype is currently under construction, marking a significant step toward advancing our understanding of the early universe's thermal history.

Bull, P., El-Makadema, A., Garsden, H., Edgley, J., Roddis, N., Chluba, J., Conselice, C. J., Dutta, S., Glasscock, K. A., Nasirudin, A., Norris, J., Wilensky, M. J., Ye, I., & Zhang, Z. (2025). RHINO: a large horn antenna for detecting the 21 cm global signal. RAS Techniques and Instruments, 4. https://doi.org/10.1093/rasti/rzaf046