We will have two presentations this month from Kirsten Hall (Harvard CfA) and Colby Jurgenson (Harvard CfA) on dusty star-forming galaxies with ACT and the G-CLEF instrument on GMT respectively. Titles and abstracts below. This will be the last webinar for this academic year, we’ll see you back after summer in September!
Abstract: We model the far-infrared spectral energy distributions (SEDs) of 71 dusty star-forming galaxies (DSFGs) selected at millimeter wavelengths by the Atacama Cosmology Tele-scope (ACT) with a lower flux density limit of 8 mJy at 220 GHz (1.4 mm). All candi-dates were cross-identified with detections in the Herschel Stripe 82 Survey (HerS) and HerMES Large Mode Survey (HELMS) at 500, 350, and 250 μm. We employ the prob-abilistic cataloging (PCAT) algorithm to decompose Herschel fluxes into multiple com-ponents, and further explore the physical nature of the DSFGs. We obtained targeted observations of nineteen of our sources using the Submillimeter Array (SMA) telescope to acquire high resolution imaging and flux extraction to compare to the ACT 220 GHz flux as well as assess the validity of the case for multiple components. Thirteen of these nineteen sources are evidenced to have missing flux in the single dish observations or have multiple components/extended structure. In this talk, I will present these findings and discuss the physical properties of the galaxies if they are treated as single sources with flux densities indicated by the single dish observations. I will then highlight the need for more efficient mapping of DSFG environments out to high redshift.
Abstract: The GMT-Consortium Large Earth Finder (G-CLEF) is a designed fiber-fed, optical echelle spectrograph (350 to 950 nm) that is to be a first light instrument for the Giant Magellan Telescope (GMT). G-CLEF will have four resolution modes (23k ≤ R ≤ 110k) with a precision radial velocity (PRV) goal of 10 cm/sec in the highest resolution mode. A dichroic in the G-CLEF spectrograph optical train separates light into a blue (350 to 540 nm) and a red (540 to 950 nm) channel, each with its own camera optics. This pa-per will provide an overview of the assembly, integration, and verification (AIV) activities that have begun on the red channel camera optics. The 7-element optical system has been assembled and is undergoing testing. Each element has been aligned within its individual bezel to within ±6 µm in centration, and ±40 µrad in tilt. The AIV setup measures three performance metrics: 1) wavefront error in double-pass, 2) camera stand-alone wavelength trajectory, and 3) VPH grating + camera wavelength trajectory. Interferometric double-pass measured the on-axis wavefront error at 632 nm to be 50.4 nm RMS (λ/13). The camera stand-alone wavelength trajectory tests resulted in < 30% (1.46 nm RMS) of the allotted error budget (5.04 nm RMS) for 80% encircled energy. Volume Phase Holographic (VPH) cross-disperser plus camera wavelength trajectory tests are currently underway.