文章基本信息

标题：COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses
其他标题：XVI. Time delays for the quadruply imaged quasar DES J0408−5354 with high-cadence photometric monitoring⋆
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作者：F. Courbin ; V. Bonvin ; E. Buckley-Geer 等
期刊名称：Astronomy & Astrophysics
印刷版ISSN：0004-6361
电子版ISSN：1432-0746
出版年度：2018
卷号：609
DOI：10.1051/0004-6361/201731461
语种：English
出版社：EDP Sciences
摘要：We present time-delay measurements for the new quadruple imaged quasar DES J0408−5354, the first quadruple imaged quasar found in the Dark Energy Survey (DES). Our result is made possible by implementing a new observational strategy using almost daily observations with the MPIA 2.2 m telescope at La Silla observatory and deep exposures reaching a signal-to-noise ratio of about 1000 per quasar image. This data qualityallows us to catch small photometric variations (a few mmag rms) of the quasar, acting on temporal scales much shorter than microlensing, and hence making the time delay measurement very robust against microlensing. In only seven months we very accurately measured one of the time delays in DES J0408−5354:Δt(AB) = −112.1 ± 2.1days (1.8%) using only the MPIA 2.2 m data. In combination with data taken with the 1.2 mEulerSwiss telescope, we also measured two delays involving the D component of the systemΔt(AD) = −155.5 ± 12.8days (8.2%) andΔt(BD) = −42.4 ± 17.6days (41%), where all the error bars include systematics. Turning these time delays into cosmological constraints will require deepHubbleSpace Telescope (HST) imaging or ground-based adaptive optics (AO), and information on the velocity field of the lensing galaxy.
关键词：enmethods: data analysisgravitational lensing: strongcosmological parameters