Space-based Ultra-long wavelength Radio Observatory (SURO) - opening the last unexplored radio frequency regime for astronomy and space science – from the Dark Ages to the space weather
by
Jan Bergman(Swedish Institute of Space Physics, Uppsala)
→
Europe/Stockholm
FD51
FD51
Description
There is an ongoing worldwide quest to detect the highly red-shifted cosmological 21-cm signal from the Dark Ages and the Epoch of Reionization (EoR). The hyperfine 21 cm spin line of neutral hydrogen is the only radiation present that can be traced back to this highly interesting epoch, when the first stars, black holes and galaxies were formed. New large radio observatories, such as LOFAR and the upcoming SKA, have therefore chosen to prioritize such observations and have listed them among their key science objectives. The redshifts involved are extreme and falls between z=100 and z=10, which means that the cosmological 21-cm signal should now be observable in the low radio-frequency domain. More precisely, below about 160 MHz, which marks the end of the EoR, when the Universe is fully ionized and the cosmological 21-cm signal disappears. However, a large fraction of this spectrum is next to impossible to use for cosmology studies from the ground because the fluctuations are extremely weak. The ionospheric blocks signals below 10 MHz and causes severe distortions up to 30-50 MHz; above lies the commercial FM radio band, 80-120 MHz, which is completely polluted almost all over the world. Hence, observations of the Dark Ages at those frequencies can only be performed with any confidence by a space-based observatory that is put in a sufficiently radio quiet location. SURO, which is proposed as an ESA S-class mission, plans to orbit the second Sun-Earth Lagrange point. It should be capable of recording the spectrum from 21-cm emissions of this age, which would give observational evidence about the Dark Ages evolution that is currently based on theoretical models and simulations. In this seminar we will also discuss some previous efforts and proposals, aimed at observing the Dark Ages and the EoR. As well, we will touch upon the other science cases of SURO, which include an extragalactic low-frequency survey, pulsars and transients, and heliophysics and space weather. If selected, SURO has the potential of becoming the radio astronomer's equivalent to the first high-resolution X-ray space telescopes, opening the last unexplored radio frequency regime for astronomy and space science.