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arXiv 1507.04750astro-ph.GA
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用Chebyshev-Fourier函数精确的PSF匹配测光和极深场的测光红移

Accurate PSF-matched photometry and photometric redshifts for the Extreme Deep Field with the Chebyshev-Fourier functions

Y. Jiménez-Teja, N. Benítez, A. Molino, C. A. C. Fernandes

摘要:

测光红移已经成为PanStarrs、DES、J-PAS或LSST等几个最大的天文调查的基石,需要使用一致的物理孔径在不同波段精确测量星系测光。由于波长差、仪器位置和大气条件引起的点扩散函数(PSF)的形状和宽度的变化,这不是微不足道的。目前的方法,以纠正这种影响依赖于一个详细的知识的PSF特性作为一个功能的调查坐标,这可能是困难的,由于相对缺乏的恒星跟踪PSF的行为。在这里,我们表明,它是可以测量准确的,一致的多色测光,而不知道形状的PSF。切比雪夫-傅立叶函数(Chebyshev-Fourier Functions,CHEFs)可以拟合每个物体的观测轮廓,并产生不受PSF影响的高信噪比积分通量测量。这些总通量,其中包括所有的星系人口,是更有用的星系演化研究比孔径测光。我们比较使用我们的软件与传统的测光与SExtractor,使用实际数据从COSMOS调查和哈勃超深场获得的总幅度和颜色。我们还将CHEFs技术应用于最近发表的极端深场,并将结果与HUDF上的ColorPro进行比较。我们制作了一个包含35732个源(10823个,信噪比>5)的测光星表,由于XDF图像的非凡深度和波长覆盖范围,测光红移精度达到2%。

英文摘要:

Photometric redshifts, which have become the cornerstone of several of the largest astronomical surveys like PanStarrs, DES, J-PAS or the LSST, require precise measurements of galaxy photometry in different bands using a consistent physical aperture. This is not trivial, due to the variation in the shape and width of the Point Spread Function (PSF) introduced by wavelength differences, instrument positions and atmospheric conditions. Current methods to correct for this effect rely on a detailed knowledge of the PSF characteristics as a function of the survey coordinates, which can be difficult due to the relative paucity of stars tracking the PSF behaviour. Here we show that it is possible to measure accurate, consistent multicolour photometry without knowing the shape of PSF. The Chebyshev-Fourier Functions (CHEFs) can fit the observed profile of each object and produce high signal-to-noise integrated flux measurements unaffected by the PSF. These total fluxes, which encompass all the galaxy populations, are much more useful for Galaxy Evolution studies than aperture photometry. We compare the total magnitudes and colours obtained using our software to traditional photometry with SExtractor, using real data from the COSMOS survey and the Hubble Ultra Deep Field. We also apply the CHEFs technique to the recently published Extreme Deep Field and compare the results to those from ColorPro on the HUDF. We produce a photometric catalogue with 35732 sources (10823 with S/N>5), reaching a photometric redshift precision of 2% due to the extraordinary depth and wavelength coverage of the XDF images.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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