The fifth phase of the Sloan Digital Sky Survey, an ongoing initiative to map the universe that includes Penn State scientists, collected its very first observations of the cosmos at 1:47 a.m. on Oct. 24. This groundbreaking all-sky survey will bolster our understanding of the formation and evolution of galaxies - like our own Milky Way - and the supermassive black holes that lurk at their centers.
SDSS-V will continue the path-breaking tradition set by the survey's previous generations, the first of which began collecting data in 2000. Penn State astronomers have held leadership roles in all of five phases of the program.
"For over two decades the SDSS has made major contributions to our understanding of the universe, from asteroids in our solar system, the structure of the Milky Way, and the basic structure of the universe," said Donald Schneider, a member of the executive committee of the SDSS-V Advisory Council and distinguished professor and head of Penn State's Department of Astronomy and Astrophysics. "As we embark on this new ambitious endeavor, I have no doubt that the observations in SDSS-V, obtained using telescopes in two hemispheres, will reveal fascinating new mysteries about the cosmos."
SDSS-V will focus on the ever-changing night sky and the physical processes that drive these changes, from the flickers and flares of supermassive black holes to the back-and-forth shifts of stars being orbited by distant worlds. SDSS-V will provide the spectroscopic backbone needed to achieve the full science potential of satellites like NASA's TESS, ESA's Gaia, and the latest all-sky X-ray mission, eROSITA.
The Sloan Digital Sky Survey's fifth generation made its first observations earlier this month. This image shows a sampling of data from those first SDSS-V data. The central sky image is a single field of SDSS-V observations. The purple circle indicates the telescope's field-of-view on the sky, with the full Moon shown as a size comparison. SDSS-V simultaneously observes 500 targets at a time within a circle of this size. The left panel shows the optical-light spectrum of a quasar--a supermassive black hole at the center of a distant galaxy, which is surrounded by a disk of hot, glowing gas. The purple blob is an SDSS image of the light from this disk, which in this dataset spans about 1 arcsecond on the sky, or the width of a human hair as seen from about 21 meters (63 feet) away. The right panel shows the image and spectrum of a white dwarf --the left-behind core of a low-mass star (like the Sun) after the end of its life.
"In a year when humanity has been challenged across the globe, I am so proud of the worldwide SDSS team for demonstrating - every day - the very best of human creativity, ingenuity, improvisation and resilience. It has been a challenging period for the team, but I'm happy to say that the pandemic may have slowed us, but it has not stopped us," said SDSS-V Director Juna Kollmeier of the Carnegie Observatories.
Funded primarily by member institutions, along with grants from the Alfred P. Sloan Foundation, the U.S. National Science Foundation, and the Heising-Simons Foundation, SDSS-V will focus on three primary areas of investigation, each exploring different aspects of the cosmos using different tools in spectroscopy - a technique that reveals information about objects based on the various wavelengths of light they emit. Together these three project pillars - called "Mappers"-will observe more than six million objects in the sky, and monitor changes in more than a million of those objects over time.
The survey's Local Volume Mapper will enhance our understanding of galaxy formation and evolution by probing the interactions between the stars that make up galaxies and the interstellar gas and dust that is dispersed between them, said the researchers. The Milky Way Mapper will reveal the physics of stars in our Milky Way, the diverse architectures of its star and planetary systems, and the chemical enrichment of our galaxy since the early universe. The Black Hole Mapper will measure masses and growth over cosmic time of the supermassive black holes that reside in the hearts of galaxies as well as the smaller black holes left behind when stars die.
"I'm excited to use the new SDSS-V data to measure black-hole masses in the distant universe and investigate the powerful, galaxy-shaping winds of quasars," said W. Niel Brandt, Verne M. Willaman Professor of Astronomy and Astrophysics at Penn State.
SDSS-V will operate out of both Apache Point Observatory in New Mexico, home of the survey's original 2.5-meter telescope, and Carnegie's Las Campanas Observatory in Chile, where it uses the 2.5-meter du Pont telescope.
SDSS-V's first observations were gathered in New Mexico with existing SDSS instruments, as a necessary change of plans due to the pandemic. As laboratories and workshops around the world navigate safe reopening, SDSS-V's own suite of new innovative hardware is on the horizon - in particular, systems of automated robots to aim the fiber optic cables used to collect the light from the night sky. These will be installed at both observatories over the next year. New spectrographs and telescopes are also being constructed to enable the Local Volume Mapper observations.
"SDSS-V will continue to transform astronomy by building on a 20-year legacy of path-breaking science, shedding light on the most fundamental questions about the origins and nature of the universe," said Evan Michelson, program director at the Sloan Foundation. "It demonstrates all the hallmark characteristics that have made SDSS so successful in the past: open sharing of data, inclusion of diverse scientists, and collaboration across numerous institutions."
