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

V.D. IVANOV, M.R.L. CIONI, K. BEKKI, R. DE GRIJS, J. EMERSON, B.K. GIBSON, D. KAMATH, J.TH. VAN LOON; A.E. PIATTI; B.Q. FOR

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2015

0004-6361

Quasi--stellar objects (quasars) located behind nearby galaxies provide anexcellent absolute reference system for astrometric studies, but they aredifficult to identify because of fore- and background contamination. Deepwide--field, high angular resolution surveys spanning the entire area of nearbygalaxies are needed to obtain a complete census of such quasars. We embarked ona program to expand the quasar reference system behind the Large and the SmallMagellanic Clouds, the Magellanic Bridge, and the Magellanic Stream, connectingthe Clouds with the Milky Way. Hundreds of quasar candidates were selectedbased on their near--infrared colors and variability properties from theongoing public ESO VISTA Magellanic Clouds survey. A subset of 49 objects wasfollowed up with optical spectroscopy. We confirmed the quasar nature of 37objects (34 new identifications), four are low redshift objects, three areprobably stars, and the remaining three lack prominent spectral features for asecure classification; bona fide quasars, judging from their broad absorptionlines are located, as follows: 10 behind the LMC, 13 behind the SMC, and 14behind the Bridge. The quasars span a redshift range from z~0.5 to z~4.1. Uponcompletion the VMC survey is expected to yield a total of ~1500 quasars withY<19.32 mag, J<19.09 mag, and Ks<18.04 mag.