Systematic biases in determining dust attenuation curves through galaxy SED fitting

Jianbo Qin, Xian Zhong Zheng, Min Fang, Zhizheng Pan, Stijn Wuyts, Yong Shi, Yingjie Peng, Valentino Gonzalez, Fuyan Bian, Jia-sheng Huang, Qiu-sheng Gu, Wenhao Liu, Qinghua Tan, Dong Dong Shi, Jian Ren, Yuheng Zhang, Man Qiao, Run Wen, Shuang Liu

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Abstract

While the slope of the dust attenuation curve (δ) is found to correlate with effective dust attenuation (AV) as obtained through spectral energy distribution (SED) fitting, it remains unknown how the fitting degeneracies shape this relation. We examine the degeneracy effects by fitting SEDs of a sample of local star-forming galaxies (SFGs) selected from the Galaxy And Mass Assembly survey, in conjunction with mock galaxy SEDs of known attenuation parameters. A well-designed declining starburst star formation history is adopted to generate model SED templates with intrinsic UV slope (β0) spanning over a reasonably wide range. The best-fitting β0 for our sample SFGs shows a wide coverage, dramatically differing from the limited range of β0 < −2.2 for a starburst of constant star formation. Our results show that strong degeneracies between β0, δ, and AV in the SED fitting induce systematic biases leading to a false AV–δ correlation. Our simulation tests reveal that this relationship can be well reproduced even when a flat AV–δ relation is taken to build the input model galaxy SEDs. The variations in best-fitting δ are dominated by the fitting errors. We show that assuming a starburst with constant star formation in SED fitting will result in a steeper attenuation curve, smaller degeneracy errors, and a stronger AV–δ relation. Our findings confirm that the AV–δ relation obtained through SED fitting is likely driven by the systematic biases induced by the fitting degeneracies between β0, δ, and AV.
Original languageEnglish
Pages (from-to)765-783
Number of pages19
JournalMonthly Notices of the Royal Astronomical Society
Volume511
Issue number1
Early online date28 Jan 2022
DOIs
Publication statusPublished - 31 Mar 2022

Funding

ACKNOWLEDGEMENTS We are grateful to the anonymous referee for helpful comments and suggestions that significantly impro v ed the quality of the manuscript. This work is supported by the National Key Research and Development Program of China (2017YFA0402703), the National Science Foundation of China (12073078 and 11773076), the Major Science and Technology Project of Qinghai Province (2019-ZJ- A10), the science research grants from the China Manned Space Project with no. CMS-CSST -2021-A02, CMS-CSST -2021-A04, and CMS-CSST-2021-A07, and the Chinese Academy of Sciences (CAS) through a China-Chile Joint Research Fund (CCJRF #1809) administered by the CAS South America Centre for Astronomy (CASSACA). SW acknowledges support from the Chinese Academy of Sciences President's International Fellowship Initiative (grant no. 2022VMB0004). GAMA is a joint European-Australasian project based around a spectroscopic campaign using the Anglo-Australian Telescope . The GAMA input catalogue is based on data taken from the Sloan Digital Sk y Surv e y and the UKIRT Infrared Deep Sk y Surv e y. Complementary imaging of the GAMA regions is being obtained by a number of independent surv e y programmes, including GALEX MIS, VST KiDS, VISTA VIKING, WISE, Herschel-ATLAS, GMRT, and ASKAP providing UV to radio coverage. GAMA is funded by the STFC (UK), the ARC (Australia), the AAO, and the participating institutions. The GAMA website is http://www .gama-survey .org/.

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