低红移下经验驱动的多波段K改正
Empirically-Driven Multiwavelength K-corrections At Low Redshift
AI总结：
本文提出一种经验驱动的低红移星系多波段K改正方法，通过多项式拟合静止参考系颜色与红移关系，减少对SED模板的依赖，在WISE W4等模板约束不足的波段显著优于传统SED拟合方法。
摘要：
K改正，即观测波段流量到静止参考系波段流量的转换，对于比较不同红移处的星系至关重要。这些改正通常依赖于对星系经验或理论光谱能量分布（SED）模板的拟合。然而，模板将可靠的K改正限制在SED模型稳健的范围内。例如，在某些波段（如WISE W4），模板约束不足，导致这些波段的K改正难以确定。我们通过开发一种经验驱动的K改正方法来弥补这一不足，以减少对SED模板的依赖。我们利用星系SED在低红移（0.01 < z < 0.09）下可以描述为单参数族的特性，对K改正作为星系静止参考系颜色（在约束良好的波段中确定，例如静止参考系(g-r)）和红移的函数进行多项式拟合。对于SED模板约束良好的波段，我们的经验驱动K改正与Kcorrect的SED拟合方法以及GSWLC-M2星表（更新的中深度GALEX-SDSS-WISE遗留星表）中采用的SED模板拟合结果相当。然而，对于WISE W4波段，我们的方法显著优于现有的SED拟合K改正。我们的方法还减轻了错误模板假设的影响，并强制K改正在z = 0处为0。我们的K改正测光和代码已公开发布。
英文摘要：
K-corrections, conversions between flux in observed bands to flux in rest-frame bands, are critical for comparing galaxies at various redshifts. These corrections often rely on fits to empirical or theoretical spectral energy distribution (SED) templates of galaxies. However, the templates limit reliable K-corrections to regimes where SED models are robust. For instance, the templates are not well-constrained in some bands (e.g., WISE W4), which results in ill-determined K-corrections for these bands. We address this shortcoming by developing an empirically-driven approach to K-corrections as a means to mitigate dependence on SED templates. We perform a polynomial fit for the K-correction as a function of a galaxy's rest-frame color determined in well-constrained bands (e.g., rest-frame (g-r)) and redshift, exploiting the fact that galaxy SEDs can be described as a one parameter family at low redshift (0.01 < z < 0.09). For bands well-constrained by SED templates, our empirically-driven K-corrections are comparable to the SED fitting method of Kcorrect and SED template fitting employed in the GSWLC-M2 catalogue (the updated medium-deep GALEX-SDSS-WISE Legacy Catalogue). However, our method dramatically outperforms the available SED fitting K-corrections for WISE W4. Our method also mitigates incorrect template assumptions and enforces the K-correction to be 0 at z = 0. Our K-corrected photometry and code are publicly available.
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