http://arxiv.org/abs/1611.09459
Type Ia supernovae (SNe Ia) that are multiply imaged by gravitational lensing can extend the SN Ia Hubble diagram to very high redshifts ($z\gtrsim 2$), probe potential SN Ia evolution, and deliver high-precision constraints on $H_0$, $w$, and $\Omega_m$ via time delays. However, only one, iPTF16geu, has been found to date, and many more are needed to achieve these goals. To increase the multiply imaged SN Ia discovery rate we present a simple algorithm for identifying gravitationally lensed SN Ia candidates in cadenced, wide-field optical imaging surveys. The technique is to look for supernovae that appear to have an elliptical galaxy as their host with an absolute magnitude implied by the host’s photometric redshift that is far brighter than the absolute magnitude of a normal SN Ia (the brightest type of supernova found in elliptical galaxies). Importantly, this purely photometric method does not require the ability to resolve the lensed images for discovery. The primary sources of contamination that affect the method are AGN and star-forming galaxies, but these can be controlled using catalog cross-matches and color cuts. Highly magnified core-collapse SNe will also be discovered as a byproduct of the method. Using a Monte Carlo simulation, we forecast that the Large Synoptic Survey Telescope can discover $500$ multiply imaged SNe Ia using this technique in a 10-year $z$-band search, more than an order of magnitude improvement over previous estimates (Oguri & Marshall 2010). We also find that the Zwicky Transient Facility should find 10 multiply imaged SNe Ia using this technique in a 3-year $R$-band search — despite the fact that this survey will not resolve a single system.
D. Goldstein and P. Nugent
Wed, 30 Nov 16
8/69
Comments: 15 pages, 4 figures, submitted to ApJL
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