The Lowest of the Low: Discovery of SN 2019gsc and the Nature of Faint Iax Supernovae
The Lowest of the Low: Discovery of SN 2019gsc and the Nature of Faint Iax Supernovae
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DOI：
10.3847/2041-8213/ab76d5
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发表时间：
2020-01
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通讯作者：
S. Srivastav;S. Smartt;G. Leloudas;M. Huber;K. Chambers;D. Malesani;J. Hjorth;J. Gillanders;A. Schultz;S. Sim;K. Auchettl;J. Fynbo;C. Gall;O. McBrien;A. Rest;Kenneth W. Smith;R. Wojtak;D. Young
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作者：
S. Srivastav;S. Smartt;G. Leloudas;M. Huber;K. Chambers;D. Malesani;J. Hjorth;J. Gillanders;A. Schultz;S. Sim;K. Auchettl;J. Fynbo;C. Gall;O. McBrien;A. Rest;Kenneth W. Smith;R. Wojtak;D. Young
我们介绍了已知的最微弱的类似超新星的瞬变的发现和光学跟踪。该事件(SN 2019gsc)是由ATLAS在53Mpc的恒星形成主机上发现的。用PanSTARRS1采集了详细的多色光曲线，用北欧光学望远镜和Gemini-North获得了后续光谱。在3,000-4,000公里的低速范围内，S−-1的光谱表现出与极低亮度的SNE2010ae和2008ha相似的窄带特征，其光强曲线也表现出类似的快速衰减(ΔM15(R)=0.91±0.10mag)。SNE 2010ae和2008ha已经被归类为SNE Iax，这三颗恒星要么组成了一个不同的物理类别，要么处于这个多样化的超新星种群的极低光度端。测辐射热光曲线符合低动能爆炸(Ek∼1049erg S−1)、适度抛射质量(Mej∼0.2M⊙)和56Ni的放射性动力(MNi∼2×10−3M⊙)。用辐射传输模型(TARDIS)和以碳、氧、镁、硅和硫为主的成分很好地再现了光谱。值得注意的是，这三个极端的Iax事件都处于相似的低金属丰度恒星形成环境中。这三种观测约束的组合可能可以用近乎MCH的碳-氧-霓虹灯混合白矮星的爆燃来最好地解释，这些白矮星的形成路径很短。
We present the discovery and optical follow-up of the faintest supernova-like transient known. The event (SN 2019gsc) was discovered in a star-forming host at 53 Mpc by ATLAS. A detailed multicolor light curve was gathered with Pan-STARRS1 and follow-up spectroscopy was obtained with the Nordic Optical Telescope and Gemini-North. The spectra near maximum light show narrow features at low velocities of 3000–4000 km s−1, similar to the extremely low-luminosity SNe 2010ae and 2008ha, and the light curve displays a similar fast decline (Δm15(r) = 0.91 ± 0.10 mag). SNe 2010ae and 2008ha have been classified as SNe Iax, and together the three either make up a distinct physical class of their own or are at the extreme low-luminosity end of this diverse supernova population. The bolometric light curve is consistent with a low kinetic energy of explosion (Ek ∼ 1049 erg s−1), a modest ejected mass (Mej ∼ 0.2 M⊙), and radioactive powering by 56Ni (MNi ∼ 2 × 10−3 M⊙). The spectra are quite well reproduced with radiative transfer models (TARDIS) and a composition dominated by carbon, oxygen, magnesium, silicon, and sulfur. Remarkably, all three of these extreme Iax events are in similar low-metallicity star-forming environments. The combination of the observational constraints for all three may be best explained by deflagrations of near MCh hybrid carbon–oxygen–neon white dwarfs that have short evolutionary pathways to formation.