Name:	Gromadzki, Mariusz
Email:	mariusz.gromadzki@uv.cl
Institution:	Millennium Institute of Astrophysics, Chile & Universidad de Valparaiso, Ch
Title:	Searching for Y dwarfs at the faint limits of WISE
Topic:	Discoveries
Abstract:	A method is defined for using the maximum sensitivity of WISE to find late T and Y dwarfs, getting down to W2=16 and fainter. This requires a WISE detection only in the W2-band and uses the statistical properties of the WISE multi-frame measurements and profile fit photometry to reject contamination resulting from non-point-like objects, variables and moving sources. To trace our desired parameter space we use a control sample of isolated non-moving non-variable point sources from the SDSS, and identify a sample of 158 WISE W2-only candidates down to a signal-to-noise limit of 8. For signal-to-noise ranges >8 a large fraction of our candidates have not been previously studied, due to the constraints placed on low signal-to-noise detections. We have performed J-band photometric follow-up of our sample on various 4-8m class telescopes to measure verify the high proper motion and low temperature of these objects. The J2 and J3 filter photometry from the FourStar camera on the Baade Magellan telescope allows for the diagnosis of methane absorption in the J band. The low resolution near-IR spectroscopy of the best candidates has confirmed, to date seven T8-Y0 dwarfs. This includes one Y dwarf, which shows peculiar spectral morphology and could be the first Y0 dwarf that is a member of the old disk. We have also published a T8 and a T9 with kinematics of the thick-disk/halo, and have spectroscopically confirmed 3 additional T8-9 dwarfs one of which is the most K-band suppressed late T dwarf yet found, and another also has thick-disk/halo kinematics. We are also creating a new expanded candidate sample using an improved version of our original selection method, which we now apply to the AllWISE database. This method is sensitive to moving as well as stationary objects, and reaches down to significantly fainter limits than have been previously attempted. As the WISE mission continues, and new data products emerge, the sensitivity of our new method will continue to improve.