Enlightening the Universe behind the Milky Way Bulge I. Target selection of VVV Bulge galaxies

DUPLANCIC, FERNANDA; ALONSO, SOL; COLDWELL, GEORGINA; GALDEANO, DANIELA

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Año: 2023

0004-6361

Context. The location of the Solar System constrains the detection of extragalactic sources beyond the Milky Way plane. The opticalobservations are hampered in the so–called Zone of Avoidance (ZOA) where stellar crowding and Galactic absorption are severe.Observations at longer wavelengths are needed to discover new background galaxies and complete the census in the ZOA.Aims. The goal of this work is to identify galaxies behind the Milky Way Bulge using near-infrared (NIR) data from the VISTAVariables in Vía Láctea (VVV) survey.Methods. To this end we made use of different VISTA Science Archive (VSA) tools in order to extract relevant information frommore than 32 billion catalogued sources in the VVV Bulge region. We find that initial photometric restriction on sources from VSAvvvSource table combined with restrictions on star–galaxy separation parameters obtained from Source Extractor is a successfulstrategy to achieve acceptable levels of contamination (60%) and a high completeness (75%) in the construction of a galaxy targetsample. To decontaminate the initial target sample from Galactic sources our methodology also incorporates the visual inspection offalse colour RGB images, a crucial quality control which was carried out following a specifically defined procedure.Results. Under this methodology we find 14480 galaxy candidates in the VVV Bulge region making this sample the largest catalogueto date in the ZOA. Moreover these new sources provide a fresh picture of the Universe hidden behind the curtain of stars, dust andgas in the unexplored Milky Way Bulge region.Conclusions. The results from this work further demonstrate the potential of the VVV/VVVX survey to find and study a large numberof galaxies and extragalactic structures obscured by the Milky Way, enlightening our knowledge of the Universe in this challengingand impressive region of the sky.