Photometric Selection of Unobscured QSOs in the Ecliptic Poles: KMTNet in the South Field and Pan-STARRS in the North Field

Woowon Byun; Minjin Kim; Yun-Kyeong Sheen; Dongseob Lee; Luis C. Ho; Jongwan Ko; Kwang-Il Seon; Hyunjin Shim; Dohyeong Kim; Yongjung Kim; Joon Hyeop Lee; Hyunjin Jeong; Jong-Hak Woo; Woong-Seob Jeong; Byeong-Gon Park; Sang Chul Kim; Yongseok Lee; Sang-Mok Cha; Hyunmi Song; Donghoon Son; Yujin Yang

arXiv · 2307.15307

Photometric Selection of Unobscured QSOs in the Ecliptic Poles: KMTNet in the South Field and Pan-STARRS in the North Field

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Abstract

We search for quasi-stellar objects (QSOs) in a wide area of the south ecliptic pole (SEP) field, which has been and will continue to be intensively explored through various space missions. For this purpose, we obtain deep broadband optical images of the SEP field covering an area of $\sim$$14.5\times14.5$ deg$^2$ with the Korea Microlensing Telescope Network. The 5$\sigma$ detection limits for point sources in the $BVRI$ bands are estimated to be $\sim$22.59, 22.60, 22.98, and 21.85 mag, respectively. Utilizing data from Wide-field Infrared Survey Explorer, unobscured QSO candidates are selected among the optically point-like sources using the mid-infrared (MIR) and optical-MIR colors. To further refine our selection and eliminate any contamination not adequately removed by the color-based selection, we perform the spectral energy distribution fitting with archival photometric data ranging from optical to MIR. As a result, we identify a total of 2,383 unobscured QSO candidates in the SEP field. We also apply a similar method to the north ecliptic pole field using the Pan-STARRS data and obtain a similar result of identifying 2,427 candidates. The differential number count per area of our QSO candidates is in good agreement with those measured from spectroscopically confirmed ones in other fields. Finally, we compare the results with the literature and discuss how this work will be implicated in future studies, especially with the upcoming space missions.

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Woowon Byun, Minjin Kim, Yun-Kyeong Sheen, Dongseob Lee, Luis C. Ho, Jongwan Ko, Kwang-Il Seon, Hyunjin Shim, Dohyeong Kim, Yongjung Kim, Joon Hyeop Lee, Hyunjin Jeong, Jong-Hak Woo, Woong-Seob Jeong, Byeong-Gon Park, Sang Chul Kim, Yongseok Lee, Sang-Mok Cha, Hyunmi Song, Donghoon Son, Yujin Yang. 2023-07-28. Photometric Selection of Unobscured QSOs in the Ecliptic Poles: KMTNet in the South Field and Pan-STARRS in the North Field. https://arxiv.org/abs/2307.15307

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