VIRUS: A hugely replicated integral field spectrograph for HETDEX

Hill, Gary J.; MacQueen, Phillip J.; Palunas, Povilas; Kelz, Andreas; Roth, Martin; Gebhardt, Karl; Grupp, F.

doi:10.1016/j.newar.2006.02.023

Cited by 32 publications

(30 citation statements)

References 7 publications

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“…The Extended Baryon Oscillation Spectroscopic Survey (eBOSS) will complie 250,000 new, spectroscopically confirmed luminous red galaxies, which yield measurements of d A with 1.2% precision and measurements of H(z) with 2.1% precision (Dawson et al 2016). HETDEX will perform a survey of 800,000 Lyα emission-line galaxies at 1.8 < z < 3.7 (Hill et al 2006). The precision on d A and H(z) is of order 2% using BAO.…”

Section: Discussionmentioning

confidence: 99%

New Model-Independent Method to Test the Curvature of The universe

Wang

2016

ApJ

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We propose a new model-independent method to test the cosmic curvature by comparing the proper distance and transverse comoving distance. Using the measurements of Hubble parameter H(z) and angular diameter distance d A , the cosmic curvature parameter Ω K is constrained to be −0.09±0.19, which is consistent with a flat universe. We also use Monte Carlo simulation to test the validity and efficiency, and find that our method can give a reliable and efficient constraint on cosmic curvature. Compared with other model-independent methods testing the cosmic curvature, our method can avoid some drawbacks and give a better constraint.

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Section: Discussionmentioning

confidence: 99%

New Model-Independent Method to Test the Curvature of The universe

Wang

2016

ApJ

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“…HETDEX plans a survey of 800,000 Lyα emission-line galaxies over 420 square degrees at redshifts 1.8 < z < 3.7, using a blind-pointing strategy with a large set of integral-field spectrographs (Hill et al, 2006). The forecast precision on D A and H is of order 2% from BAO alone, with additional gain possible if one can take advantage of the increased linearity of the large-scale density field at high redshift to model the full anisotropic clustering signal of the galaxies.…”

Section: Prospectsmentioning

confidence: 99%

Observational probes of cosmic acceleration

et al. 2013

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The accelerating expansion of the universe is the most surprising cosmological discovery in many decades, implying that the universe is dominated by some form of "dark energy" with exotic physical properties, or that Einstein's theory of gravity breaks down on cosmological scales. The profound implications of cosmic acceleration have inspired ambitious efforts to understand its origin, with experiments that aim to measure the history of expansion and growth of structure with percent-level precision or higher. We review in detail the four most well established methods for making such measurements: Type Ia supernovae, baryon acoustic oscillations (BAO), weak gravitational lensing, and the abundance of galaxy clusters. We pay particular attention to the systematic uncertainties in these techniques and to strategies for controlling them at the level needed to exploit "Stage IV" dark energy facilities such as BigBOSS, LSST, Euclid, and WFIRST. We briefly review a number of other approaches including redshift-space distortions, the Alcock-Paczynski effect, and direct measurements of the Hubble constant H 0 . We present extensive forecasts for constraints on the dark energy equation of state and parameterized deviations from General Relativity, achievable with Stage III and Stage IV experimental programs that incorporate supernovae, BAO, weak lensing, and cosmic microwave background data. We also show the level of precision required for clusters or other methods to provide constraints competitive with those of these fiducial programs. We emphasize the value of a balanced program that employs several of the most powerful methods in combination, both to cross-check systematic uncertainties and to take advantage of complementary information. Surveys to probe cosmic acceleration produce data sets that support a wide range of scientific investigations, and they continue the longstanding astronomical tradition of mapping the universe in ever greater detail over ever larger scales.

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“…Note that if the f/ratio of the microlens case is the same as the f/ratio from the telescope in the bare-fiber case, and the lenslets subtend the same area on the sky as the bare fibers, then the fill-factor of the densepak type array is exactly offset by the larger area that the bundle covers per exposure. So in the case where maximum areal coverage is required, the bare bundle is the preferred solution 2 .…”

Section: Integral Field Unitmentioning

confidence: 99%

“…Wide-field IF spectroscopy is hard to achieve without a large multiplexing factor, so we have embarked on a program to produce an instrument that uses large-scale replication to create a unique astronomical facility capable of spectroscopic surveys of hundreds of square degrees of sky. The instrument is the Visible Integral-field Replicable Unit Spectrograph (VIRUS) 1,2,3 , a simple, modular integral field spectrograph that is to be replicated 150-fold, to provide an order of magnitude increase in grasp over any existing spectrograph, when mounted on the upgraded Hobby-Eberly Telescope (HET) 4 .…”

Section: Introductionmentioning

confidence: 99%

Design, construction, and performance of VIRUS-P: the prototype of a highly replicated integral-field spectrograph for HET

et al. 2008

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We describe the design, construction, and performance of VIRUS-P (Visible Integral-field Replicable Unit Spectrograph -Prototype), the prototype for 150+ identical fiber-fed integral field spectrographs for the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX ‡ ). VIRUS-P was commissioned in 2007, is in regular service on the McDonald Observatory 2.7 m Smith telescope, and offers the largest field of any integral field spectrograph. The 246-fiber IFU uses a densepak-type fiber bundle with a 1/3 fill factor. It is fed at f/3.65 through a telecentric, two-group dioptric focal reducer. The spectrograph's double-Schmidt optical design uses a volume phase holographic grating at the pupil between the articulating f/3.32 folded collimator and the f/1.33 cryogenic prime focus camera. High on-sky throughput is achieved with this catadioptric system by the use of high reflectivity dielectric coatings, which set the 340-670 nm bandwidth. VIRUS-P is gimbal-mounted on the telescope to allow short fibers for high UV throughput, while maintaining high mechanical stability. The instrument software and the 18 square arcmin field, fixed-offset guider provide rapid acquisition, guiding, and precision dithering to fill in the IFU field. Custom software yields Poisson noise limited, sky subtracted spectra. The design characteristics are described that achieved uniformly high image quality with low scattered light and fiber-to-fiber cross talk. System throughput exceeds requirements and peaks at 40%. The observing procedures are described, and example observations are given.

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VIRUS: A hugely replicated integral field spectrograph for HETDEX

Cited by 32 publications

References 7 publications

New Model-Independent Method to Test the Curvature of The universe

New Model-Independent Method to Test the Curvature of The universe

Observational probes of cosmic acceleration

Design, construction, and performance of VIRUS-P: the prototype of a highly replicated integral-field spectrograph for HET

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