Gaia Data Release 3. The Galaxy in your preferred colours. Synthetic photometry from Gaia low-resolution spectra
Gaia Data Release 3. The Galaxy in your preferred colours. Synthetic photometry from Gaia low-resolution spectra
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盖亚数据发布 3。银河系有您喜欢的颜色。
DOI：
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发表时间：
2022
期刊：
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通讯作者：
Gaia Dpac
中科院分区：
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作者：
Gaia Collaboration;P. Montegriffo;M. Bellazzini;F. Angeli;R. Andrae;M. Barstow;D. Bossini;A. Bragaglia;P. Burgess;C. Cacciari;J. Carrasco;N. Chornay;L. Delchambre;D. Evans;M. Fouesneau;Y. Frémat;D. Garabato;C. Jordi;M. Manteiga;D. Massari;L. Palaversa;E. Pancino;M. Riello;D. Mieres;N. Sanna;R. Santoveña;R. Sordo;A. Vallenari;N. Walton;Gaia Dpac
Gaia数据发布3提供了新的通量校准低分辨率分光光度法，波长范围为330nm - 1050nm （XP光谱）的约2.2亿个光源。直接与物理单位的通量相联系的合成光度测定可以从这些光谱中获得完全封闭在该波长范围内的任何通带。我们描述了如何从XP光谱中获得合成光度，说明了在一系列不同条件下（例如通带宽度和波长范围）可以实现的性能，以及影响它的限制和问题。现有的高质量光度法可以在很宽的星等和颜色范围内，在宽波段和中等波段内，在几个百分点的范围内复制，并且在合成光度法相对于这些外部来源标准化时，精度可达毫安。提出了一些潜在科学应用的例子，包括探测球状星团中的多个种群，估计金属丰度扩展到非常缺金属的状态，以及白矮星的分类。提供了一个在几个广泛使用的光度测量系统的宽波段中为约2.2亿个光源提供标准化光度测量的目录（Gaia Synthetic photometry catalog； GSPC），以及一个使用随机森林算法获得的具有DA/非DA分类的$simeq 10^5$白矮星目录（Gaia Synthetic photometry catalog for white dwarfs; GSPC- wd）。
Gaia Data Release 3 provides novel flux-calibrated low-resolution spectrophotometry for about 220 million sources in the wavelength range 330nm - 1050nm (XP spectra). Synthetic photometry directly tied to a flux in physical units can be obtained from these spectra for any passband fully enclosed in this wavelength range. We describe how synthetic photometry can be obtained from XP spectra, illustrating the performance that can be achieved under a range of different conditions - for example passband width and wavelength range - as well as the limits and the problems affecting it. Existing top-quality photometry can be reproduced within a few per cent over a wide range of magnitudes and colour, for wide and medium bands, and with up to millimag accuracy when synthetic photometry is standardised with respect to these external sources. Some examples of potential scientific application are presented, including the detection of multiple populations in globular clusters, the estimation of metallicity extended to the very metal-poor regime, and the classification of white dwarfs. A catalogue providing standardised photometry for ~220 million sources in several wide bands of widely used photometric systems is provided (Gaia Synthetic Photometry Catalogue; GSPC) as well as a catalogue of $simeq 10^5$ white dwarfs with DA/non-DA classification obtained with a Random Forest algorithm (Gaia Synthetic Photometry Catalogue for White Dwarfs; GSPC-WD).