Ultra-Luminous Supernovae as a New Probe of the Interstellar Medium in Distant Galaxies
E. Berger, R. Chornock, R. Lunnan, R. Foley, I. Czekala, A. Rest, C. Leibler, A. M. Soderberg, K. Roth, G. Narayan, M. E. Huber, D. Milisavljevic, N. E. Sanders… 展开作者
E. Berger, R. Chornock, R. Lunnan, R. Foley, I. Czekala, A. Rest, C. Leibler, A. M. Soderberg, K. Roth, G. Narayan, M. E. Huber, D. Milisavljevic, N. E. Sanders, M. Drout, R. Margutti, R. P. Kirshner, G. H. Marion, P. J. Challis, A. G. Riess, S. J. Smartt, W. S. Burgett, J. N. Heasley, N. Kaiser, R. -P. Kudritzki, E. A. Magnier, M. McCrum, P. A. Price, K. Smith, J. L. Tonry, R. J. Wainscoat
We present the Pan-STARRS1 discovery and light curves, and follow-up MMT and Gemini spectroscopy of an ultra-luminous supernova (ULSN; dubbed PS1-11bam) at a redshift of z=1.566 with a peak brightness of M_UV=-22.3 mag. PS1-11bam is one of the highest redshift spectroscopically-confirmed SNe known to date. The spectrum is characterized by broad absorption features typical of previous ULSNe (e.g., CII, SiIII), and by strong and narrow MgII and FeII absorption lines from the interstellar medium (ISM) of the host galaxy, confirmed by an [OII]3727 emission line at the same redshift. The equivalent widths of the FeII2600 and MgII2803 lines are in the top quartile of the quasar intervening absorption system distribution, but are weaker than those of gamma-ray burst intrinsic absorbers (i.e., GRB host galaxies). We also detect the host galaxy in pre-explosion Pan-STARRS1 data and find that its UV spectral energy distribution is best fit with a young stellar population age of tau~15-45 Myr and a stellar mass of M \sim (1.1-2.6)x10^9 M_sun (for Z=0.05-1 Z_sun). The star formation rate inferred from the UV continuum and [OII]3727 emission line is ~10 M_sun/yr, higher than in any previous ULSN host. PS1-11bam provides the first direct demonstration that ULSNe can serve as probes of the interstellar medium in distant galaxies. At the present, the depth and red sensitivity of PS1 are uniquely suited to finding such events at cosmologically interesting redshifts (z~1-2); the future combination of LSST and 30-m class telescopes promises to extend this technique to z~4.
Lacerta I and Cassiopeia III: Two luminous and distant Andromeda satellite dwarf galaxies found in the 3π Pan-STARRS1 survey
We report the discovery of two new dwarf galaxies, Lacerta I/Andromeda XXXI (Lac I/And XXXI) and Cassiopeia III/Andromeda XXXII (Cas III/And XXXII), in stacked Pan-STARRS1 r_P1- and i_P1-band imaging data. Both are luminous systems (M_V ~ -12) located at projected distances of 20.3° and 10.5° from M31. Lac I and Cas III are likely satellites of the Andromeda galaxy with heliocentric distances of 756^{+44}_{-28} kpc and 772^{+61}_{-56} kpc, respectively, and corresponding M31-centric distances of 275+/-7 kpc and 144^{+6}_{-4} kpc . The brightest of recent Local Group member discoveries, these t…
On the diversity of super-luminous supernovae: ejected mass as the dominant factor
我们收集了24个贫氢超亮超新星（SLSNe）的样本。通过上升和下降时间尺度对光变曲线形状进行参数化，表明两者高度相关。磁动力模型可以再现相关性，扩散时间尺度驱动的上升和下降速率的多样性。星周相互作用模型可以表现出类似的上升-下降关系，但仅适用于窄范围的密度，这对这些模型来说可能是有问题的。我们发现SLSNe比SNe Ibc亮约3.5个星等，光变曲线宽3倍，但内在形状相似。有一些SLSNe具有特别宽的光变曲线，可能表明两个祖通道，但统计学检验不能完全区分两个群体。给出了一般的谱演化。从Fe II测得的速度是相似的SLSNe和SNe IBC，这表明扩散时间差主要由质量或不透明度。在大多数SLSNe平坦的速度演变表明喷出物的致密外壳。如果SLSNe的不透明度与其他SNe Ibc相似，则平均喷射质量高出2-3倍。假设$κ=0.1\,$ cm $^2\,$ g $^{-1}$，我们估计SLSN喷出物质量的平均值（中位数）为10 $\,$ M $_\odot$（6 $\,$ M $_\odot$），范围为3-30 $\,$ M $_\odot$。将假定的不透明度加倍，使质量更接近正常的SNe Ibc，但有一个高质量的尾部。SLSNe最可能的产生机制似乎是一颗质量非常大的贫氢恒星的核心坍缩，形成毫秒磁星。
