The Dark Energy Survey Supernova Program: Cosmological Biases from Host Galaxy Mismatch of Type Ia Supernovae
The Astrophysical Journal(2023)
摘要
Redshift measurements, primarily obtained from host galaxies, are essential
for inferring cosmological parameters from type Ia supernovae (SNe Ia).
Matching SNe to host galaxies using images is non-trivial, resulting in a
subset of SNe with mismatched hosts and thus incorrect redshifts. We evaluate
the host galaxy mismatch rate and resulting biases on cosmological parameters
from simulations modeled after the Dark Energy Survey 5-Year (DES-SN5YR)
photometric sample. For both DES-SN5YR data and simulations, we employ the
directional light radius method for host galaxy matching. In our SN Ia
simulations, we find that 1.7
with redshift difference between the true and matched host of up to 0.6. Using
our analysis pipeline, we determine the shift in the dark energy equation of
state parameter (Dw) due to including SNe with incorrect host galaxy matches.
For SN Ia-only simulations, we find Dw = 0.0013 +/- 0.0026 with constraints
from the cosmic microwave background (CMB). Including core-collapse SNe and
peculiar SNe Ia in the simulation, we find that Dw ranges from 0.0009 to 0.0032
depending on the photometric classifier used. This bias is an order of
magnitude smaller than the expected total uncertainty on w from the DES-SN5YR
sample of around 0.03. We conclude that the bias on w from host galaxy mismatch
is much smaller than the uncertainties expected from the DES-SN5YR sample, but
we encourage further studies to reduce this bias through better host-matching
algorithms or selection cuts.
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关键词
Cosmology,Type Ia supernovae,Dark energy
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