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Gravitational lensing of type Ia supernovae by galaxy clusters |
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| Authors: | Tsafrir S Kolatt & Matthias Bartelmann |
| Institution: | The Physics Department and Lick Observatory, University of California, Santa Cruz, CA 95064, USA,;Max-Planck-Institut für Astrophysik, PO Box 1523, D-85740 Garching, Germany |
| Abstract: | We propose a method to remove the mass-sheet degeneracy that arises when the mass of galaxy clusters is inferred from gravitational shear. The method utilizes high-redshift standard candles that undergo weak lensing. Natural candidates for such standard candles are type Ia supernovae (SNe Ia). When corrected with the light-curve shape (LCS), the peak magnitude of SNe Ia provides a standard candle with an uncertainty in apparent magnitude of Δ m ?0.1–0.2. Gravitational magnification of a background SN Ia by an intervening cluster would cause a mismatch between the observed SN Ia peak magnitude compared with that expected from its LCS and redshift. The average detection rate for SNe Ia with a significant mismatch of ≥2Δ m behind a cluster at z ?0.05–0.15 is about 1–2 supernovae per cluster per year at J , I , R ?25–26. Since SNe are point-like sources for a limited period, they can experience significant microlensing by massive compact halo objects (MACHOs) in the intracluster medium. Microlensing events caused by MACHOs of ～10 |
| Keywords: | methods: miscellaneous galaxies: clusters: general dark matter gravitational lensing |