arXiv 1602.027572016-02astro-ph.GA

一个滑动斜率：线宽重子Tully-Fisher关系的系统不确定性

A Slippery Slope: Systematic Uncertainties in the Line Width Baryonic Tully-Fisher Relation

Jeremy D. Bradford, Marla C. Geha, Frank C. van den Bosch

备注：: Accepted by the Astrophysical Journal, figures 2 and 3 present our key results, all data are available at http://www.astro.yale.edu/jdbradford/research.html
DOI：: 10.3847/0004-637X/832/1/11

摘要：

重子Tully-Fisher关系（BTFR）是一种很有价值的观测工具，也是对星系形成理论的重要检验。我们探讨了系统的不确定性的斜率和分散的观测线宽BTFR利用均匀测量，未解决的HI观测930孤立星系。我们测量了$\log_{10}{M_{\rm baryon}} = 3.24\log_{10}{V_{\rm rot}}+3.21$与$10^{7.4} < M_{\rm baryon} < 10^{11.3}M_{\odot}$的置信关系，其中$V_{\rm rot}$是从20\% HI线宽测量的。我们改变了$M_{\rm baryon}$和$V_{\rm rot}$的定义、样本选择和线性拟合算法。我们得到的斜率范围从2.64到3.53和散射测量范围从0.14到0.41 dex，表明系统的不确定性0.25的BTFR斜率来自未解决的HI线宽。我们将我们的基准斜率与文献测量值进行比较，其中报告的斜率范围从3.0到4.3，并且散射是不可测量的，不可测量的或大到0.4 dex。从未分辨HI线宽获得的测量结果倾向于产生3.3的斜率，而从渐近旋转曲线获得的测量结果倾向于产生3.9的斜率。影响BTFR斜率的最大因素是$V_{\rm rot}$的定义。样品定义、质量范围和线性拟合算法也显著影响测得的BTFR。我们发现，在我们的样本与$V_{\rm rot} < 100~\rm{km~s^{-1}}$的星系是一致的更大质量的星系的线宽BTFR，但这些星系驱动的大部分观察到的散射。在将预测值与观测到的BTFR进行比较时，关键是$V_{\rm rot}$定义、样本选择和拟合算法的定义相似。我们建议直接的数据集之间的统计比较，而不是比较BTFR的幂律拟合可验证的属性。

英文摘要：

The baryonic Tully-Fisher relation (BTFR) is a valuable observational tool and a critical test of galaxy formation theory. We explore the systematic uncertainty in the slope and the scatter of the observed line width BTFR utilizing homogeneously measured, unresolved HI observations for 930 isolated galaxies. We measure a fiducial relation of $\log_{10}{M_{\rm baryon}} = 3.24\log_{10}{V_{\rm rot}}+3.21$ with observed scatter of 0.25 dex with $10^{7.4} < M_{\rm baryon} < 10^{11.3}M_{\odot}$ where $V_{\rm rot}$ is measured from 20\% HI line widths. We vary the definitions of $M_{\rm baryon}$ and $V_{\rm rot}$, the sample selection, and the linear fitting algorithm. We obtain slopes ranging from 2.64 to 3.53 and scatter measurements ranging from 0.14 to 0.41~dex, indicating a systematic uncertainty of 0.25 in the BTFR slope derived from unresolved HI line widths. We compare our fiducial slope to literature measurements, where reported slopes range from 3.0 to 4.3 and scatter is either unmeasured, immeasurable or as large as 0.4~dex. Measurements derived from unresolved HI line widths tend to produce slopes of 3.3, while measurements derived from asymptotic rotation curves tend to produce slopes of 3.9. The largest factor affecting the BTFR slope is the definition of $V_{\rm rot}$. The sample definition, the mass range, and the linear fitting algorithm also significantly affect the measured BTFR. We find that galaxies in our sample with $V_{\rm rot} < 100~\rm{km~s^{-1}}$ are consistent with the line width BTFR of more massive galaxies, but these galaxies drive most of the observed scatter. It is critical when comparing predictions to an observed BTFR that the $V_{\rm rot}$ definition, the sample selection and the fitting algorithm are similarly defined. We recommend direct statistical comparisons between data sets with commensurable properties as opposed to comparing BTFR power-law fits.

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英文摘要：

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