186 research outputs found
Microlensing of Lensed Supernovae
Given the number of recently discovered galaxy-galaxy lens systems, we
anticipate that a gravitationally lensed supernova will be observed within the
next few years. We explore the possibility that stars in the lens galaxy will
produce observable microlensing fluctuations in lensed supernova light curves.
For typical parameters, we predict that ~70% of lensed SNe will show
microlensing fluctuations > 0.5 mag, while ~25% will have fluctuations > 1 mag.
Thus microlensing of lensed supernova will be both ubiquitous and observable.
Additionally, we show that microlensing fluctuations will complicate
measurements of time delays from multiply imaged supernovae: time delays
accurate to better than a few days will be difficult to obtain. We also
consider prospects for extracting the lens galaxy's stellar mass fraction and
mass function from microlensing fluctuations via a new statistical measure, the
time-weighted light curve derivative.Comment: 13 pages, emulateapj format; accepted in ApJ; expanded discussion of
time delay uncertaintie
Statistical Bias in the Hubble Constant and Mass Power Law Slope for Mock Strong Lenses
Strong gravitational lensing offers constraints on the Hubble constant that
are independent of other methods. However, those constraints are subject to
uncertainties in lens models. Previous studies suggest that using an elliptical
power law + external shear (EPL+XS) for the lensing galaxy can yield results
that are precise but inaccurate. We examine such models by generating and
fitting mock lenses which produces multiple images of a background quasar-like
point source. Despite using the same model for input and output, we find
statistical bias in the Hubble constant on the order of 3% to 5%, depending on
whether the elliptical lenses have noise or not. The phase space distribution
has a `flared' shape that causes the mass power law slope to be underestimated
and the Hubble constant to be overestimated. The bias varies with image
configuration, which we quantify through annulus length between images with the
first and second time delays (). The statistical bias is worse
for configurations that have narrow annuli (e.g., symmetric cross
configurations). Assuming a source at redshift 2.0 and an EPL+XS lens at
redshift 0.3, we find that the bias can be reduced, but not eliminated, if we
limit the sample to systems with annulus lengths
arcsec. As lens samples grow, it may be helpful to prioritize this range of
image configurations for follow-up observation and analysis.Comment: Submitted to MNRA
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