Bright Type IIP Supernovae in Low-Metallicity Galaxies. (arXiv:1812.06559v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Scott_S/0/1/0/all/0/1">Spencer Scott</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nicholl_M/0/1/0/all/0/1">Matt Nicholl</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Blanchard_P/0/1/0/all/0/1">Peter Blanchard</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gomez_S/0/1/0/all/0/1">Sebastian Gomez</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Berger_E/0/1/0/all/0/1">Edo Berger</a>
We present measurements of the pseudo-equivalent width of the Fe
II,$lambda$5018 absorption feature in the spectra of 12 Type IIP supernovae
(SNe II) in low luminosity ($M>-17$) dwarf host galaxies. The Fe
II,$lambda$5018 line has been suggested to be a useful diagnostic of the
metallicity of the SN progenitor stars. The events in our sample were
discovered photometrically by the Pan-STARRS Survey for Transients (PSST), and
classified spectroscopically by us. Comparing our sample to 24 literature SNe
II, we find that those in low luminosity hosts have significantly weaker Fe II
features, with a probability of $10^{-4}$ that the two samples are drawn from
the same distribution. Since low-mass galaxies are expected to contain a lower
fraction of metals, our findings are consistent with a metallicity dependence
for Fe II,$lambda$5018, and therefore support the use of this line as a
metallicity probe, in agreement with a number of recent works. In addition, we
find that the SNe in faint (low-metallicity) hosts may be more luminous on
average than those in the literature sample, suggesting possible physical
differences between Type IIP SNe at low and high metallicity. However, accurate
determinations of host galaxy extinction will be needed to quantify such an
effect.
We present measurements of the pseudo-equivalent width of the Fe
II,$lambda$5018 absorption feature in the spectra of 12 Type IIP supernovae
(SNe II) in low luminosity ($M>-17$) dwarf host galaxies. The Fe
II,$lambda$5018 line has been suggested to be a useful diagnostic of the
metallicity of the SN progenitor stars. The events in our sample were
discovered photometrically by the Pan-STARRS Survey for Transients (PSST), and
classified spectroscopically by us. Comparing our sample to 24 literature SNe
II, we find that those in low luminosity hosts have significantly weaker Fe II
features, with a probability of $10^{-4}$ that the two samples are drawn from
the same distribution. Since low-mass galaxies are expected to contain a lower
fraction of metals, our findings are consistent with a metallicity dependence
for Fe II,$lambda$5018, and therefore support the use of this line as a
metallicity probe, in agreement with a number of recent works. In addition, we
find that the SNe in faint (low-metallicity) hosts may be more luminous on
average than those in the literature sample, suggesting possible physical
differences between Type IIP SNe at low and high metallicity. However, accurate
determinations of host galaxy extinction will be needed to quantify such an
effect.
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