期刊
ASTRONOMICAL JOURNAL
卷 144, 期 6, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/0004-6256/144/6/177
关键词
supernovae: general
资金
- NASA [NNX-08AV63G]
- NSF [PHY-0801007, AST1109801]
- Australian Research Council Center of Excellence for All-sky Astrophysics (CAASTRO) [CE110001020]
- National Science Foundation [1066293]
- National Aeronautics and Space Administration's Earth Science Technology Office, Computation Technologies Project [NCC5-626]
- Direct For Mathematical & Physical Scien
- Division Of Physics [801007] Funding Source: National Science Foundation
We present a sample of 23 spectroscopically confirmed Type Ia supernovae (SNe Ia) that were discovered in the background of galaxy clusters targeted by ROTSE-IIIb and use up to 18 of these to determine the local ((z) over bar = 0.05) volumetric rate. Since our survey is flux limited and thus biased against fainter objects, the pseudo-absolute magnitude distribution (pAMD) of SNe Ia in a given volume is an important concern, especially the relative frequency of high-to low-luminosity SNe Ia. We find that the pAMD derived from the volume-limited Lick Observatory Supernova Search (LOSS) sample is incompatible with the distribution of SNe Ia in a volume-limited (z < 0.12) sub-sample of the Sloan Digital Sky Survey II (SDSS-II). The LOSS sample requires far more low-luminosity SNe Ia than the SDSS-II can accommodate. Even though LOSS and SDSS-II have sampled different SNe Ia populations, their volumetric rates are surprisingly similar. Using the same model pAMD adopted in the SDSS-II SNe Ia rate calculation and excluding two high-luminosity SNe Ia from our sample, we derive a rate that is marginally higher than previous low-redshift determinations. With our full sample and the LOSS pAMD, our rate is more than double the canonical value. We also find that 5 of our 18 SNe Ia are hosted by very low luminosity (M-B > -16) galaxies, whereas only 1 out of 79 nearby SDSS-II SNe Ia have such faint hosts. It is possible that previous works have undercounted either low-luminosity SNe Ia, SNe Ia in low-luminosity hosts, or peculiar SNe Ia (sometimes explicitly), and the total SNe Ia rate may be higher than the canonical value.
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