New quasars behind the Magellanic Clouds. Spectroscopic confirmation of near-infrared selected candidates

Ivanov, Valentin D.; Cioni, Maria-Rosa L.; Bekki, Kenji; de Grijs, Richard; Emerson, Jim; Gibson, Brad K.; Kamath, Devika; van Loon, Jacco Th.; Piatti, Andrés E.; For, Bi-Qing

Abstract

Context. Quasi-stellar objects (quasars) located behind nearby galaxies provide an excellent absolute reference system for astrometric studies, but they are difficult to identify because of fore- and background contamination. Deep wide-field, high angular resolution surveys spanning the entire area of nearby galaxies are needed to obtain a complete census of such quasars. Aims. We embarked on a program to expand the quasar reference system behind the Large and the Small Magellanic Clouds, the Magellanic Bridge, and the Magellanic Stream that connects the Clouds with the Milky Way. Methods. Hundreds of quasar candidates were selected based on their near-infrared colors and variability properties from the ongoing public ESO VISTA Magellanic Clouds survey. A subset of 49 objects was followed up with optical spectroscopy. Results. We confirmed the quasar nature of 37 objects (34 new identifications): four are low redshift objects, three are probably stars, and the remaining three lack prominent spectral features for a secure classification. The bona fide quasars, identified from their broad emisison lines, are located as follows: 10 behind the LMC, 13 behind the SMC, and 14 behind the Bridge. The quasars span a redshift range from z ~ 0.5 to z ~ 4.1. Conclusions. Upon completion the VMC survey is expected to yield a total of ~1500 quasars with Y< 19.32 mag, J< 19.09 mag, and Ks< 18.04 mag.

Citation

Ivanov, V. D., Cioni, M.-R. L., Bekki, K., de Grijs, R., Emerson, J., Gibson, B. K., Kamath, D., van Loon, J. T., Piatti, A. E., & For, B.-Q. (2016). New quasars behind the Magellanic Clouds. Spectroscopic confirmation of near-infrared selected candidates. Astronomy and Astrophysics, 588, Article A93. https://doi.org/10.1051/0004-6361/201527398

• Acceptance Date: Oct 19, 2015
• Online Publication Date: Mar 23, 2016
• Publication Date: Apr 1, 2016
• Deposit Date: Apr 1, 2016
• Publicly Available Date: Apr 1, 2016
• Journal: Astronomy & astrophysics
• Print ISSN: 0004-6361
• Publisher: EDP Sciences
• Peer Reviewed: Peer Reviewed
• Volume: 588
• Article Number: A93
• DOI: https://doi.org/10.1051/0004-6361/201527398
• Keywords: Surveys -- infrared; Galaxies -- quasars; General -- Magellanic Clouds
• Public URL: https://hull-repository.worktribe.com/output/434674
• Publisher URL: http://www.aanda.org/articles/aa/abs/2016/04/aa27398-15/aa27398-15.html
• Additional Information: Copy of article first published in: Astronomy & astrophysics, 2016, v.588
• Contract Date: Apr 1, 2016