Measuring the Distance to the Far Side of the Galaxy
2MASS Redshift Survey
Galaxies are distributed in long filaments, huge “walls”, and large clusters, which astronomers call the large-scale structure of the cosmos. This structure is a tracer of dark matter, and is a way to understand how the universe has evolved. The 2MASS Redshift Survey (2MRS) is an ambitious map of the galaxies relatively close to the Milky Way. Led by astronomers at the Center for Astrophysics | Harvard & Smithsonian, 2MRS used data collected from the Two Micron All-Sky Survey (2MASS), which is an an atlas of the entire sky in infrared light. The completed 2MRS project resulted in a three-dimensional view of the distributions of nearby galaxies, providing a way to understand the structure of the modern universe and distribution of dark matter.
AbacusSummit is the world’s largest suite of high-performance cosmological N-body simulations, developed to meet and exceed the analysis requirements of the Dark Energy Spectroscopic Instrument. These simulations allow one to predict the large-scale structure that results from a wide range of cosmological models, enabling detailed investigations of theories of cosmological structure formation and comparison to the coming decade of observational surveys.
Dark Energy Spectroscopic Instrument (DESI)
The Dark Energy Spectroscopic Instrument (DESI) consortium is conducting a five-year survey to map the large-scale structure of the Universe over one-third of the sky and 11 billion years of cosmic history, aiming to study the physics of dark energy.
GMACS - Moderate Dispersion Optical Spectrograph for the Giant Magellan Telescope is a powerful optical spectrograph that will unlock the power of the Giant Magellan Telescope for research ranging from the formation of stars and planets to cosmology.
Sloan Digital Sky Survey (SDSS)
The Sloan Digital Sky Survey continues its twenty-year legacy of wide-field optical/infrared imaging and spectroscopy, which has led astronomy into the era of large archives and data science. Harvard and Smithsonian are both full institutional members of the latest epoch of the survey, SDSS-V, which started observations in 2020.
Large galaxies and galaxy clusters sometimes act like lenses. Their gravity distorts the structure of spacetime, magnifying light from more distant objects. This effect, known as strong gravitational lensing, allows astronomers to study galaxies that would ordinarily be too far to see, map the distribution of mass in the galaxies doing the lensing, and measure the expansion rate of the universe. The CASTLeS (CfA-Arizona Space Telescope Lens Survey) is a program jointly managed by the Center for Astrophysics | Harvard & Smithsonian and the University of Arizona, which used NASA’s Hubble Space Telescope to study multiple aspects of strong gravitational lensing as caused by galaxies. Today, CASTLeS team members maintain a catalog of these lenses, updated with new observational data.
CfA Redshift Catalog
The universe is expanding, carrying galaxies with it like flotsam on a fast-flowing river. This expansion also stretches the wavelength of light, which astronomers call cosmological redshift, since it pushes visible light colors toward the red end of the spectrum. That means astronomers can determine the distance to far-away galaxies by measuring the redshift of light they produce. The CfA Redshift Catalog (ZCAT), created by researchers at the Center for Astrophysics | Harvard & Smithsonian, is a clearinghouse for historical redshift data from a number of observatories, including the 1.5-Meter Tillinghast Telescope and the MMT Observatory, both CfA-operated telescopes located at the Fred Lawrence Whipple Observatory (FLWO) in Arizona. This data provides a map of galaxies in three dimensions, allowing astronomers to piece together how galaxies group on the largest scales in the universe. ZCAT is an essential resource for data on redshift surveys up to 2008, carrying on the legacy of the original CfA Redshift Surveys conducted in the 1970s and ‘80s.