The Consequences of Scintillation Effects on the Measurement of 21-Centimeter Radiation
Mentor:Christopher Hirata, Professor of Astrophysics, California Institute of Technology
21-centimeter radiation is electromagnetic radiation in the radio spectrum emitted when hydrogen atoms move from a higher energy state to a lower energy state. Cosmologists study 21-cm radiation from neutral hydrogen in the universe, which is measured via massive arrays of radio antennae, in order to probe the "dark ages” when galaxies first began to form. Two effects that potentially pose problems in the study of 21-cm radiation are scintillation of synchrotron radiation emitted by supermassive black holes at the centers of active galactic nuclei (AGNs) and scintillation of radiation emitted by compact sources such as pulsars, since these effects are not smooth as a function of frequency and cannot be easily subtracted from 21-cm spectra. Scintillation parameters and brightness temperatures were calculated from literature-listed quantities, and source counts were calculated from a previous semi-empirical model. Future work will consist of calculating the brightest source per beam and ultimately obtaining an upper limit to the two scintillation effects, which will provide an answer to how problematic the effects are.