TY - JOUR
T1 - Quasar lenses in the south: searches over the DES public footprint
AU - Agnello, Adriano
AU - Spiniello, Chiara
PY - 2019/10/21
Y1 - 2019/10/21
N2 - We have scanned 5000 deg2 of Southern Sky to search for strongly lensed quasars with five methods, all source oriented, but based on different assumptions and selection criteria. We present a list of high-grade candidates from each method (totalling 98 unique, new candidates), to facilitate follow-up spectroscopic campaigns, including two previously unknown quadruplets, WG 210014.9-445206.4 and WG 021416.37-210535.3. We analyse morphological searches based on Gaia multiplet detection and astrometric offsets, fibre-spectroscopic preselection, and X-ray and radio pre-selection. The performance and complementarity of the methods are evaluated on a common sample of known lenses in the Dark Energy Survey public Data Release 1 (DR1) footprint.We recovered in total 13 known lenses, of which 8 are quadruplets. Morphological and colour selection of objects, from the WISE and Gaia-DR2 surveys, recovers most of those known lenses, but searches in the radio and X-ray cover regimes that are beyond the completeness of Gaia. Given the footprint, pre-selection, and depth limits, the current number of quads indicates that the union of these searches is complete, and the expected purity on high-grade candidates is ≈60 per cent. Ongoing, spectroscopic campaigns confirm this estimate.
AB - We have scanned 5000 deg2 of Southern Sky to search for strongly lensed quasars with five methods, all source oriented, but based on different assumptions and selection criteria. We present a list of high-grade candidates from each method (totalling 98 unique, new candidates), to facilitate follow-up spectroscopic campaigns, including two previously unknown quadruplets, WG 210014.9-445206.4 and WG 021416.37-210535.3. We analyse morphological searches based on Gaia multiplet detection and astrometric offsets, fibre-spectroscopic preselection, and X-ray and radio pre-selection. The performance and complementarity of the methods are evaluated on a common sample of known lenses in the Dark Energy Survey public Data Release 1 (DR1) footprint.We recovered in total 13 known lenses, of which 8 are quadruplets. Morphological and colour selection of objects, from the WISE and Gaia-DR2 surveys, recovers most of those known lenses, but searches in the radio and X-ray cover regimes that are beyond the completeness of Gaia. Given the footprint, pre-selection, and depth limits, the current number of quads indicates that the union of these searches is complete, and the expected purity on high-grade candidates is ≈60 per cent. Ongoing, spectroscopic campaigns confirm this estimate.
KW - catalogues
KW - galaxies: formation
KW - dark matter
U2 - 10.1093/mnras/stz2200
DO - 10.1093/mnras/stz2200
M3 - Journal article
SN - 0035-8711
VL - 489
SP - 2525
EP - 2535
JO - Royal Astronomical Society. Monthly Notices
JF - Royal Astronomical Society. Monthly Notices
IS - 2
ER -