EXP-SN · Mapping the cosmic expansion history with Type Ia supernovae
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2021-09-01 → 2023-08-31
- EU contribution
- €212,934
- Participants
- 1
- Scheme
- MSCA-IF
Lines connect the coordinator with its partners.
Results in brief
Mapping the cosmic expansion history with Type Ia supernovae
Measuring the expansion rate of the universe, termed as the Hubble Constant has been a central problem in cosmology. It is especially interesting currently since the prediction from the well-tested, standard model of cosmology is in strong tension with the direct measurement from the local distance scale. This local measurement is constructed from observations of distant exploding stars, known as Type Ia supernovae, calibrated to pulsating Cepheid variable stars in more nearby galaxies that have hosted Type Ia supernovae. With several obvious causes for this “Hubble tension” ruled out, it remains to be seen whether that is a sign of new and exotic cosmological physics or some unknown sources of systematic uncertainty in the measurement. The overall objective of the fellowship project is to develop novel methods for understanding the cause of the discrepancy. This is extremely important, since if independent methods agree with the direct measurement of the Hubble Constant, it would strongly suggest the presence of exciting new cosmology, e.g. dark radiation before the universe became transparent, or phantom-like behaviour of dark energy. Towards achieving this objective, my project was setup to develop new statistical tools for analyses of cutting edge datasets from time-domain surveys, like the Zwicky Transient Facility, constructing new cosmological probes like strongly lensed supernovae and forecasting the constraints expected from the Vera C. Rubin Observatory’s Legacy Survey of Space and Time. The problem is central to our curiosity about the history, composition and evolution of the universe.
Data: CORDIS, © European Union
Project objective
Observations of distant Type Ia supernovae indicate that the expansion of the universe is accelerating, driven by a mysterious cosmic component called dark energy. Since the discovery, a standard model of cosmology has been established, wherein ordinary matter only consists of 5% of the energy density, the rest being dark matter (~25%) and dark energy (~70%). Recent, precision measurements of the local expansion rate, the Hubble constant, are in disagreement with the value inferred from the early universe, presenting the strongest challenge to standard cosmology. In this proposal, I will, for the first time, use gravitationally lensed Type Ia supernovae to measure the Hubble constant. Strongly lensed Type Ia supernovae are powerful probes of cosmology since the delay time between their multiple images directly measures the Hubble constant. Wide-field transient surveys like the Zwicky Transient Facility are designed to find tens of such events and hence, it is extremely timely to use them as precision probes in cosmology.Moreover, I will use the Hubble diagram of unlensed Type Ia supernovae in the near infrared to understand the nature of dark energy. Supernova cosmology in the conventional optical wavelengths is limited by systematic uncertainties. Hence, the near infrared is an exciting wavelength regime to improve them as cosmological probes. Type Ia supernovae are more uniform in the near infrared than the optical and there is significantly less extinction from host galaxy dust. Additionally, I will quantify the constraints on dark energy from future experiment, e.g. the Large Synoptic Survey Telescope.
Original text from CORDIS.
Participants
- THE CHANCELLOR MASTERS AND SCHOLARS OF THE UNIVERSITY OF CAMBRIDGE · CAMBRIDGECoordinatorUnited Kingdom
Links
Data: CORDIS, © European Union