TDSS additionally devotes a number of fibers to both "few-epoch spectroscopy" (FES) and to "repeat quasar spectroscopy" (RQS), and these both study optical spectroscopic variability. Future photometric surveys (such as the Large Synoptic Survey Telescope) will leverage TDSS observations to classify their detections more robustly. By spectroscopically identifying the physical nature of 100,000 detected variables, TDSS will greatly enhance the power of these existing data sets to illuminate the physics of stars and quasars. These targets include quasars and multiple classes of variable stars, some of which may reveal previously unidentified phenomena. The Time-Domain Spectroscopic Survey (TDSS) selects photometrically variable targets (especially from Pan-STARRS 1 and archival SDSS imaging) for spectroscopic follow-up. Principal Investigators Paul Green (SAO/CfA) and Scott Anderson (UW) Recent Targeting Coordinator Chelsea MacLeod (formerly SAO/CfA) Recent Data Coordinator John Ruan (formerly UW recently McGill) The combination of eBOSS with the SPIDERS, X-ray selected quasar sample and the TDSS, variability selected AGN sample, creates a unique window to the full population of quasars at all epochs to redshift z = 3. This region corresponds to the epoch when the Universe was transitioning from deceleration due to the effects of gravity, to the current epoch of acceleration. The figure to the right shows the region newly mapped by the eBOSS project. In filling this gap, eBOSS creates the largest volume survey of the Universe to date. Dark Energy remains one of the most mysterious experimental results in modern physics.ĮBOSS concentrates on the observation of galaxies and quasars, in a range of distances (redshifts) currently left completely unexplored by other three-dimensional maps of large-scale structure in the Universe. These measurements improve constraints on the nature of "Dark Energy", the observed phenomenon that the expansion of the Universe is currently accelerating. When combined with previous phases of SDSS, eBOSS precisely measures the expansion history of the Universe throughout eighty percent of cosmic history, back to when the Universe was less than three billion years old. Image Credit: Dana Berry / SkyWorks Digital Inc. At higher redshifts, during a time when the Universe was matter-dominated, eBOSS uses the Lyman-alpha forest to map out the matter distribution. EBOSS maps the distribution of galaxies and quasars from when the Universe was 3 to 8 billion years old, a critical time when dark energy started to affect the expansion of the Universe.
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