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

V. IVANOV + 7 COLS.; A.E. PIATTI; B.Q. FOR

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2016 vol. 588 p. 1 - 11

0004-6361

Context. Quasi?stellar objects (quasars) located behind nearby galaxies provide an excellent absolute reference system for astrometricstudies, but they are difficult to identify because of fore- and background contamination. Deep wide?field, high angular resolutionsurveys 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, theMagellanic Bridge, and the Magellanic Stream, connecting the Clouds with the Milky Way.Methods. Hundreds of quasar candidates were selected based on their near?infrared colors and variability properties from the ongoingpublic 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 probablystars, and the remaining three lack prominent spectral features for a secure classification; bona fide quasars, judging from their broadabsorption lines are located, as follows: 10 behind the LMC, 13 behind the SMC, and 14 behind the Bridge. The quasars span aredshift 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, andK s <18.04 mag.