HETDEX Dark Energy Experiment Begins Full Operations

Hobby-Eberly Telescope at Dusk

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The Hobby-Eberly Telescope at sunset. The flags of the 4 partner organizations fly with the U.S. flag outside the open dome. Credit: Ethan Tweedie Photography

Three years after its preliminary test observations, the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) is now training its complete suite of instrumentation to expose the nature and development of dark energy, the strange entity that is the main constituent of deep space.

HETDEX, which is a big worldwide consortium led by the University of Texas at Austin and includes around 100 researchers consisting of Penn State scientists, prepares to build among the biggest maps of the universes ever made. The three-dimensional map of 2.5 million galaxies will assist astronomers to much better comprehend why the growth of deep space is presently speeding up.

“Penn State is delighted to be a participant in this fundamental scientific investigation,” stated Donald Schneider, a member of the Hobby-Eberly Telescope (HET) Board of Directors and Distinguished Professor and Head of Penn State’s Department of Astronomy and Astrophysics. “The telescope’s innovative design was by two Penn State astronomers, Lawrence Ramsey and Daniel Weedman, and a number of Penn State astronomers are playing important roles in the observations and data analysis in HETDEX.”

Hobby Eberly Telescope Saddlebags

The 2 black structures to the left and right of the Hobby-Eberly Telescope’s primary mirror are nicknamed ‘saddlebags.’ They hold the lots of spectrographs that comprise the INFECTION instrument created to carry out HETDEX, the Hobby-Eberly Telescope Dark Energy Experiment. Credit: Ethan Tweedie Photography

HETDEX is utilizing the 10-meter HET, situated at McDonald Observatory in western Texas, to get information from 2 big areas of the sky; one field remains in the instructions of the Big Dipper, the other is a little southwest of the constellation of Orion. Each time the telescope is pointed at these areas, which generally last 20 minutes, HETDEX’s instrumentation records around 32,000 spectra, recording the cosmic finger print of the light from every item within the 10-meter telescope’s field of vision.

“HETDEX has arrived,” stated University of Texas astronomer Karl Gebhardt, who is the study’s job researcher. “We’re over a third of the way through our program now, and we have this fantastic dataset that we’re going to use to measure the dark energy evolution.”

HETDEX is a “blind” study; instead of pointing at particular targets, it tape-records light from all sources over a particular spot of sky. These spectra are tape-recorded through 32,000 fiber optics that feed into more than 100 instruments interacting as a single spectrograph. This assembly, the Visible Integral-field Replicable Unit Spectrograph (INFECTION), is an intricate system including lots of copies of an instrument interacting for performance. INFECTION was created and constructed specifically for HETDEX.

Hobby Eberly Telescope Focal Surface

This image reveals the ‘focal surface’ of the Hobby-Eberly Telescope, where the fiber optics of INFECTION are arrayed. The circles each include a square grid of 448 fibers. When the telescope is pointed and INFECTION takes an observation, each of the 32,000 fibers takes a spectrum at the same time, tape-recording a large range of info on the speed, instructions, and chemical makeup of every point inside the field of vision, which has to do with the size of the complete Moon. Credit: J. Pautzke/E. Mrozinski/G. Hill/HETDEX Collaboration

Building INFECTION “was quite a task to orchestrate,” stated Gary Hill, a University of Texas astronomer and the designer of the instrument. “It’s the largest on many measures,” he stated, keeping in mind that it has the most fiber optics, along with having as much detector location as the biggest huge video cameras. INFECTION is likewise an exceptionally enforcing instrument, declaring much of the volume inside the telescope dome.

The HETDEX group anticipates to finish their observations by December 2023. In overall, the finished study will consist of one billion spectra, “the largest ever spectral survey by far,” Gebhardt stated.

“To investigate the properties of dark matter and its evolution, we must identify a few million galaxies of a specific type in the roughly one billion HETDEX spectra and create a map of their three-dimensional distribution,” described Donghui Jeong, associate teacher of astronomy and astrophysics at Penn State and leader of the HETDEX science group examining big scale structures in deep space. “By examining the locations of these galaxies, we can compare the observations to models of dark energy and determine the influence of ordinary matter, dark matter, and dark energy at various points in the history of the universe.”

HETDEX Pinwheel Galaxy

This false-color picture of the Pinwheel Galaxy (Messier 101) reveals the power of the INFECTION instrument constructed for the HETDEX study. The image is a mosaic comprised of the main part of 21 INFECTION pointings throughout an area of sky about half the size of the complete Moon, with some little spaces in protection. The colors reveal the contrast in between young stars (blue/white) and older stars (red/orange). The breakout boxes reveal simply 4 examples of the ‘cosmic fingerprint’ of things in this view. Clockwise from leading left: a white dwarf in our galaxy, an active galaxy 11 billion light-years away, a star-forming area in the Pinwheel Galaxy 20 million light-years away, and a star-forming galaxy 3 billion light-years away. Credit: G. Zeimann/HETDEX Collaboration

Other Penn State HETDEX individuals consist of Professor of Astronomy and Astrophysics Robin Ciardullo, who is the observations supervisor for HETDEX, Research Professor Caryl Gronwall, and Associate Professor Derek Fox.

“The galaxies that will be studied in HETDEX are from the universe’s distant past,” stated Gronwall. “The light we detect left these objects approximately ten billion years ago, when the universe was but a few billion years of age.”

Taft Armandroff, director of The University of Texas at Austin’s McDonald Observatory and Chair of the HET Board of Directors, kept in mind, “HETDEX represents the coming together of many astronomers and institutions to conduct the first major study of how dark energy changes over time.”

HETDEX is led by The University of Texas at Austin McDonald Observatory and Department of Astronomy with involvement from Penn State; Ludwig Maximilians University, Munich; the Max Planck Institute for Extraterrestrial Physics; the Institute for Astrophysics, Gottingen; the Leibniz Institute for Astrophysics, Potsdam; Texas A&M University; The University of Oxford; the Max Planck Institute for Astrophysics; The University of Tokyo; and the Missouri University of Science and Technology.

In addition to Institutional assistance, HETDEX is moneyed by the National Science Foundation (grant AST-0926815), the State of Texas, the United States Air Force (AFRL FA9451-04-2-0355), and generous assistance from personal people and structures.

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