Type Ia supernovae (SNe Ia) play a key role in recent advances in our understanding of the Universe. We present cosmological applications of SNe Ia, including observational results as part of an ongoing campaign at the Harvard Smithsonian Center for Astrophysics to monitor newly discovered SNe Ia at the F. L. Whipple Observatory (FLWO). We describe observations and analysis of SN 1998bu in M96, the only SN Ia yet to have appeared in a galaxy with a previously measured Hubble Space Telescope Cepheid distance. We show that SN 1998bu was a normal, reddened SN Ia and use it to constrain the Hubble constant, with attention to systematic uncertainties. We also present the largest set of SN Ia photometry published to date, consisting of 2190 UBVRI FLWO CCD observations of 44 SNe Ia discovered between 1997 and 2000. The large, homogeneous sample of U-band light curves is unique, with important applications to SN Ia at high redshift, and we present the first detailed description of SN Ia U-band properties. We also develop MLCS2k2, a new incarnation of the Multicolor Light Curve Shape method to measure SN Ia distances, incorporating the U-band and other improvements. Application of MLCS2k2 to a large sample of Hubble-flow and Cepheid-calibrated SNe Ia yields an estimate of H 0 = 66 ± 3 (random) ± 7 (systematic) or 76 ± 3 ± 8 km s−1 Mpc−1, depending on which of two discrepant sets of Cepheid distances is used. With the High-Z SN Search Team, we present cosmological constraints on the dark energy equation of state, and combined constraints on ΩM and ΩA from SNe Ia and the cosmic microwave background. Finally, via observations at FLWO, we measure the redshift of an extremely distant exploding star, GRB 010222, at z = 1.477.
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机译：Ia型超新星（SNe Ia）在我们对宇宙的理解的最新进展中起着关键作用。我们介绍了SNe Ia的宇宙学应用，包括观测结果，这是哈佛史密森尼天体物理学中心正在进行的一项活动的一部分，目的是在F. L. Whipple天文台（FLWO）监测新发现的SNe Ia。我们描述了对M 1998年SN 1998bu的观测和分析，这是唯一一个以先前测量的哈勃太空望远镜造父变星距离出现在星系中的SN Ia。我们表明SN 1998bu是正常的，发红的SN Ia，并使用它来约束哈勃常数，并注意系统的不确定性。我们还展示了迄今为止已发布的最大的SN Ia光度集，其中包括1997年至2000年之间发现的2项44个SNe Ia的2190个 UBVRI FLWO CCD观测值。斜体>-带光曲线是独特的，在高红移下对于SN Ia具有重要的应用，并且我们将首先对SN Ia U -带特性进行详细描述。我们还开发了MLCS2k2，这是一种多色光曲线形状方法的新形式，用于测量SN Ia距离，并结合了 U 波段和其他改进功能。将MLCS2k2应用到哈勃流和造父变星校准的SNe Ia的大量样本中，得出的估计值 H 0 = 66±3（随机）±7（系统性）或76±3±8 km s −1 Mpc −1 ，具体取决于使用两个造父变星距离的哪一组。通过High-Z SN搜索团队，我们提出了暗能量状态方程的宇宙学约束，以及来自SNe Ia和宇宙的Ω M 和Ω A 的组合约束微波背景。最后，通过FLWO的观测，我们在 z = 1.477处测量了一颗极远距离爆炸星GRB 010222的红移。
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