Browsing by Subject "Integral field spectrograph"

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    Integral field spectroscopy : instrumentation and a new window into low-redshift galaxy populations
    (2021-05-07) Indahl, Briana; Hill, Gary J.; Finkelstein, Steven; Casey, Caitlin; Drory, Niv; McQuinn, Kristen; Bershady, Matthew; Chisholm, John
    Integral field spectrographs (IFS) have transformed studies of low-redshift spatially resolved galaxies as they provide simultaneous spectral coverage over contiguous spatial regions. IFS surveys of galaxies have allowed for observations of the spatially varying physical diagnostics of galaxy disks. Though IFS instruments have been traditionally limited to small fields of view (FOV), on the order of 100 square arcseconds, constraining the extent to which IFS studies can map the most nearby galaxies. Small FOV have also restricted IFS studies of large galaxy samples to pre-selected targets. Scaling up the fields of IFS instruments is challenging due to the limited number of spatial elements that can be imaged on a single CCD. To cost effectively scale up IFS capability in order to observe larger fields, the Visible Integral-field Replicable Unit Spectrograph (VIRUS) utilizes massive replication on an unprecedented 100-fold scale to be able to image ∼35,000 fibers over a ∼22 arcminute FOV with a single observation. VIRUS consists of up to 78 replicable units, each with two integral field spectrograph channels. The VIRUS design takes advantage of large-scale replication of simple units to significantly reduce engineering and production costs of building a facility instrument of this scale. With VIRUS being 156 realizations of the same spectrograph and the first to be replicated on this massive scale, I present analysis that uncovers the statistical variations in performance of these units along with an assessment of cost/tolerance trade offs of scaling up instrument capabilities through massively replicated designs. The VIRUS instrument was designed to conduct the Hobby Eberly Telescope Dark Energy Experiment (HETDEX) which intends to build a sample of nearly a million Lyα emitting galaxies (LAEs) from 1.9