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arXiv 1206.2210astro-ph.CO
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SDSS-II SN巡天中Ia型超新星的性质与宿主星系距离的关系

Type Ia Supernova Properties as a Function of the Distance to the Host Galaxy in the SDSS-II SN Survey

Lluis Galbany, Ramon Miquel, Linda Ostman, Peter J. Brown, David Cinabro, Chris B. D'Andrea, Joshua Frieman, Saurabh W. Jha, John Marriner, Robert C. Nichol, Ja… 展开作者

Lluis Galbany, Ramon Miquel, Linda Ostman, Peter J. Brown, David Cinabro, Chris B. D'Andrea, Joshua Frieman, Saurabh W. Jha, John Marriner, Robert C. Nichol, Jakob Nordin, Matthew D. Olmstead, Masao Sako, Donald P. Schneider, Mathew Smith, Jesper Sollerman, Kaike Pan, Stephanie Snedden, Dmitry Bizyaev, Howard Brewington, Elena Malanushenko, Viktor Malanushenko, Dan Oravetz, Audrey Simmons, Alaina Shelden

摘要:

我们使用SDSS-II SN巡天发现的Ia型超新星(SNe Ia)来搜索SN Ia属性与到宿主星系中心的投影距离之间的依赖关系,使用距离作为局部星系属性(局部恒星形成率,局部金属丰度等)的代理。该样品由近200个光谱学或光度学证实的Ia超新星组成,红移低于0.25。根据宿主星系的形态,样本被分成两组。我们使用MLCS 2k 2和SALT 2拟合光变曲线,并确定每个Ia超新星的颜色(AV,c)和光变曲线形状(delta,x1)参数,以及它在哈勃图中的残差。然后,我们将这些参数与到宿主星系中心的物理距离和归一化距离相关联,并寻找这些参数的平均值和散射随距离增加的趋势。最重要的(在4-sigma水平)发现是,平均拟合AV从MLCS 2k 2和c从SALT 2的螺旋星系的SNe Ia的投影距离下降。我们还发现,在椭圆星系的SNe往往有更窄的光变曲线,如果他们在更大的距离爆炸的迹象,虽然这可能是由于在我们的样本中的选择效应。我们没有找到很强的相关性之间的残差的距离模量相对于哈勃流量和银河系的距离,这表明有限的SN幅度之间的相关性后,标准化和本地主机金属丰度。

英文摘要:

We use type-Ia supernovae (SNe Ia) discovered by the SDSS-II SN Survey to search for dependencies between SN Ia properties and the projected distance to the host galaxy center, using the distance as a proxy for local galaxy properties (local star-formation rate, local metallicity, etc.). The sample consists of almost 200 spectroscopically or photometrically confirmed SNe Ia at redshifts below 0.25. The sample is split into two groups depending on the morphology of the host galaxy. We fit light-curves using both MLCS2k2 and SALT2, and determine color (AV, c) and light-curve shape (delta, x1) parameters for each SN Ia, as well as its residual in the Hubble diagram. We then correlate these parameters with both the physical and the normalized distances to the center of the host galaxy and look for trends in the mean values and scatters of these parameters with increasing distance. The most significant (at the 4-sigma level) finding is that the average fitted AV from MLCS2k2 and c from SALT2 decrease with the projected distance for SNe Ia in spiral galaxies. We also find indications that SNe in elliptical galaxies tend to have narrower light-curves if they explode at larger distances, although this may be due to selection effects in our sample. We do not find strong correlations between the residuals of the distance moduli with respect to the Hubble flow and the galactocentric distances, which indicates a limited correlation between SN magnitudes after standardization and local host metallicity.

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