Two distant brown dwarfs in the UKIRT Infrared Deep Sky Survey Deep Extragalactic Survey Data Release 2

Lodieu, N.; Dobbie, P. D.; Deacon, N. R.; Venemans, B. P.; Durant, M.
Bibliographical reference

Monthly Notices of the Royal Astronomical Society, Volume 395, Issue 3, pp. 1631-1639.

Advertised on:
5
2009
Number of authors
5
IAC number of authors
2
Citations
10
Refereed citations
8
Description
We present the discovery of two brown dwarfs in the UK infrared Telescope (UKIRT) Infrared Deep Sky Survey (UKIDSS) Deep Extragalactic Survey (DXS) Data Release 2 (DR2). Both objects were selected photometrically from 6deg2 in DXS for their blue J - K colour and the lack of optical counterparts in the Sloan Digital Sky Survey (SDSS) Stripe 82. Additional optical photometry provided by the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) corroborated the possible substellarity of these candidates. Subsequent methane imaging of UDXS J221611.51+003308.1 and UDXS J221903.10+002418.2 has confirmed them as T7 +/- 1 and T6 +/- 1 dwarfs at photometric distances of 81 (52-118 pc) and 60 (44-87 pc; 2σ confidence level). A similar search in the DR2 of the Ultra-Deep Survey over a smaller area (0.77deg2) and shallower depth did not return any late-T dwarf candidate. The numbers of late-T dwarfs in our study are broadly in line with a declining mass function when considering the current area and depth of the DXS and UDS. These brown dwarfs are the first discovered in the Visible Imaging Multi-Object Spectrograph (VIMOS) 4 field and among the few T dwarfs found in pencil-beam surveys. They are valuable to investigate the scaleheight of T dwarfs. Based on observations made with the United Kingdom Infrared Telescope, the Canada-France-Hawaii Telescope Legacy Survey and the Gemini Observatory. E-mail: nlodieu [at] iac.es (nlodieu[at]iac[dot]es)