S. Cristiani, K. Boutsia, G. Calderone, G. Cupani, V. D'Odorico, F. Fontanot, A. Grazian, F. Guarneri, C. J. A. P. Martins, L. Pasquini, M. Porru, E. Vanzella
Abstract
The redshift drift is a small, dynamic change in the redshift of objects following the Hubble flow. Its measurement provides a direct, real-time, model-independent mapping of the expansion rate of the Universe. It is fundamentally di erent from other cosmological probes: instead of mapping our (present-day) past light-cone, it directly compares di erent past light-cones. Being independent of any assumptions on gravity, geometry or clustering, it directly tests the pillars of the Lambda CDM paradigm. Recent theoretical studies have uncovered unique synergies with other cosmological probes, including the characterization of the physical properties of dark energy. At the time of the original proposal by Sandage (1962) the expected change in the redshift of objects at cosmological distances appeared to be exceedingly small for reasonable observing times and beyond technological capabilities. In the last decades progress in the spectrographs (e.g. ESPRESSO), in the collecting area of telescopes and in the samples of cosmic beacons, enabled by new datasets and new machine-learning-based selections, have drastically changed the situation, bringing the Redshift Drift Grail within reach. As a consequence, this measurement is a flagship objective of the Extremely Large Telescope (ELT), specifically of its high-resolution spectrograph, ANDES.
Keywords
Cosmology: observations; Spectroscopy; Astrophysics - Cosmology and Nongalactic Astrophysics; Astrophysics - Instrumentation and Methods for Astrophysics
Proceedings of the Conference "Past, Present and Future of Astrophysical Spectroscopy", Memorie della Società Astronomica Italiana
P. Bonifacio and P. Molaro
Italian Astronomical Society
Volume 94, Number 2, Page 251
2023 September
