200 most important Astronomy topics - Sykalo Eugen 2023


The Sloan Digital Sky Survey-IV (SDSS-IV)

The Sloan Digital Sky Survey-IV (SDSS-IV) is a major astronomical survey which aims to map the universe and provide data to help answer fundamental questions about its structure and evolution. The survey is a collaboration between many institutions and individuals from around the world, and uses a range of telescopes, instruments and techniques to observe and analyze the sky.

Background

The SDSS-IV builds on the legacy of the previous SDSS surveys, which began in 2000 and have produced some of the most detailed and extensive maps of the universe ever made. The SDSS has been instrumental in advancing our understanding of galaxy formation and evolution, the distribution of dark matter, and the large-scale structure of the universe.

The SDSS-IV began in 2014 and is scheduled to run until 2020. It is divided into several programs, each of which has different scientific goals and uses different observational techniques. These programs include:

  • The Apache Point Observatory Galactic Evolution Experiment (APOGEE), which focuses on studying the chemical and dynamical properties of stars in the Milky Way and other nearby galaxies.
  • The Mapping Nearby Galaxies at APO (MaNGA), which uses a technique called integral field spectroscopy to study the spatially resolved properties of galaxies in the nearby universe.
  • The Extended Baryon Oscillation Spectroscopic Survey (eBOSS), which aims to measure the expansion history of the universe and the distribution of matter on large scales.
  • The Time Domain Spectroscopic Survey (TDSS), which studies the variability and properties of objects that change in brightness on short time scales, such as supernovae and quasars.

Observations and Data

The SDSS-IV uses a range of telescopes and instruments to observe the sky in different wavelengths of light, from ultraviolet to near-infrared. The main telescope used for SDSS-IV observations is the 2.5-meter Sloan Foundation Telescope at Apache Point Observatory in New Mexico, USA. The survey also uses smaller telescopes and facilities around the world to supplement its observations.

The SDSS-IV produces a vast amount of data, including images, spectra, and catalogs of objects such as stars, galaxies, and quasars. The data is publicly available and can be accessed through the SDSS website or through various catalogs and data repositories.

Scientific Discoveries

The SDSS-IV has already made many important scientific discoveries, and will continue to do so as more data is analyzed and released. Some of the key discoveries and results from the survey so far include:

  • The discovery of a new class of galaxy in the nearby universe, called "ultra-diffuse galaxies", which are much larger and fainter than normal galaxies.
  • Precise measurements of the distances to galaxies and quasars, which have helped to refine our understanding of the expansion history of the universe and the nature of dark energy.
  • Detailed maps of the distribution of matter in the universe, which have revealed the large-scale structure of the cosmic web and the imprint of baryon acoustic oscillations (BAOs) on the distribution of galaxies.
  • Studies of the chemical and dynamical properties of stars in the Milky Way and other nearby galaxies, which have provided insights into the formation and evolution of galaxies and the processes that drive stellar evolution.

Future Prospects

The SDSS-IV will continue to produce data and make scientific discoveries for several years to come. In addition to the ongoing programs, there are several new programs and initiatives planned for the survey's final years, including:

  • The Local Volume Mapper (LVM), which will use a new instrument to study the properties of stars and galaxies in the nearby universe.
  • The Dark Energy Spectroscopic Instrument (DESI), which will use a new spectrograph to study the large-scale structure of the universe and the nature of dark energy.
  • The Southern Sky Survey, which will use a new telescope in Chile to observe the southern hemisphere sky and complement the SDSS-IV's northern hemisphere observations.