Core-Collapse Supernovae from the Palomar Transient Factory: Indications for a Different Population in Dwarf Galaxies
Iair Arcavi, Avishay Gal-Yam, Mansi M. Kasliwal, Robert M. Quimby, Eran O. Ofek, Shrinivas R. Kulkarni, Peter E. Nugent, S. Bradley Cenko, Joshua S. Bloom, Mark… 展开作者
Iair Arcavi, Avishay Gal-Yam, Mansi M. Kasliwal, Robert M. Quimby, Eran O. Ofek, Shrinivas R. Kulkarni, Peter E. Nugent, S. Bradley Cenko, Joshua S. Bloom, Mark Sullivan, D. Andrew Howell, Dovi Poznanski, Alexei V. Filippenko, Nicholas Law, Isobel Hook, Jakob Jonsson, Sarah Blake, Jeff Cooke, Richard Dekany, Gustavo Rahmer, David Hale, Roger Smith, Jeff Zolkower, Viswa Velur, Richard Walters, John Henning, Kahnh Bui, Dan McKenna, Janet Jacobsen
We use the first compilation of 72 core-collapse supernovae (SNe) from the Palomar Transient Factory (PTF) to study their observed subtype distribution in dwarf galaxies compared to giant galaxies. Our sample is the largest single-survey, untargeted, spectroscopically classified, homogeneous collection of core-collapse events ever assembled, spanning a wide host-galaxy luminosity range (down to M_r ~ -14 mag) and including a substantial fraction (>20%) of dwarf (M_r >= -18 mag) hosts. We find more core-collapse SNe in dwarf galaxies than expected and several interesting trends emerge. We use detailed subclassifications of stripped-envelope core-collapse SNe and find that all Type I core-collapse events occurring in dwarf galaxies are either SNe Ib or broad-lined SNe Ic (SNe Ic-BL), while "normal" SNe Ic dominate in giant galaxies. We also see a significant excess of SNe IIb in dwarf hosts. We hypothesize that in lower metallicity hosts, metallicity-driven mass loss is reduced, allowing massive stars that would have appeared as "normal" SNe Ic in metal-rich galaxies to retain some He and H, exploding as Ib/IIb events. At the same time, another mechanism allows some stars to undergo extensive stripping and explode as SNe Ic-BL (and presumably also as long-duration gamma-ray bursts). Our results are still limited by small-number statistics, and our measurements of the observed N(Ib/c)/N(II) number ratio in dwarf and giant hosts (0.25_{-0.15}^{+0.3} and 0.23_{-0.08}^{+0.11}, respectively; 1 sigma uncertainties) are consistent with previous studies and theoretical predictions. As additional PTF data accumulate, more robust statistical analyses will be possible, allowing the evolution of massive stars to be probed via the dwarf-galaxy SN population.
Real-Time Detection and Rapid Multiwavelength Follow-up Observations of a Highly Subluminous Type II-P Supernova from the Palomar Transient Factory Survey
Type Ia Supernova Spectral Features in the Context of Their Host Galaxy Properties
我们分析了122 Ia型超新星（SNe Ia）的光谱测量与Z<0.09发现的Palomar瞬态工厂，专注于Si II 6355和Ca II的“近红外三重态”的性质。我们研究的速度的光球硅II 6355，和速度和强度的光球和高速钙II，在背景下的恒星质量（Mstellar）和恒星形成率（SFR）的SN主机星系，以及在其主机的SN的位置。我们发现，具有更快Si II 6355的Ia超新星倾向于在更大质量的星系中爆炸，最高速度事件仅发生在M恒星质量> 3*10^9太阳质量的星系中。我们还发现一些证据表明，这些速度最高的超新星Ia在其宿主星系的内部区域爆炸，类似于Wang et al.（2013）的研究，尽管在我们的数据中趋势并不显著。我们表明，这些趋势是一致的一些超新星Ia光谱模型，如果宿主星系恒星质量被解释为宿主星系金属丰度的代理。我们研究的Ca II近红外吸收的高速分量的强度，并表明，SNe Ia具有较强的高速组件相对于光球组件托管的星系低恒星质量，蓝色，和一个高的sSFR。因此，这种SNe可能来自最年轻的祖细胞系统。这反对一个纯粹的取向效应负责的高速功能在超新星Ia光谱，当结合其他研究，是一致的情况下，高速功能与SN喷出物和星周介质（CSM）之间的相互作用的SN本地。
