Eight surveys for WEAVE. The paper: “The wide-field, multiplexed, spectroscopic facility WEAVE: Survey design, overview, and simulated implementation” of S. Jin (University of Oxford) appeared on MNRAS

About thirteen years ago, in January 2010, the meeting “Science with the William Herschel Telescope 2010-2020” took place at the Isaac Newton Group of telescopes (ING). During that meeting, the importance of spectroscopic surveys at medium and high resolution for various strategic fields in both galactic and extragalactic astronomy was discussed. In the same year, a document endorsed by the European Astronomical Society, as part of the ASTRONET program funded by the European Commission, outlined the necessity for a spectroscopic infrastructure capable of medium and high-resolution spectroscopy, to be installed on telescopes in the 2-4 meter class. This infrastructure was intended for complementing the Gaia science mission, conducting cosmological experiments, and studying the morphology and chemical properties of the Milky Way. After 13 years, these recommendations have taken shape in the form of the WHT Enhanced Area Velocity Explorer (WEAVE).

 

WEAVE is an instrument designed for spectroscopic observations across a wide field of view, covering  2 degrees. It is equipped with a system capable of deploying slightly less than 1000 optical fibers within the field of view. These fibers direct the light to a spectrograph, enabling observations at medium resolution (R=5000) in two broad ranges of the optical spectrum (λ=3660-6060 Å for the blue channel, 5790-9590 Å for the red channel), as well as high-resolution spectra (R=20000) in three narrower spectral windows. Additionally, WEAVE offers 20 small (1112 arcseconds) field Integral Field Units (IFUs) and one large IFU with a field of view of 1.3×1.5 arcminutes. An Integral Field Unit is an instrument that can produce a low-resolution spectrum for each pixel of an image. Following its first light in December 2022 (link), WEAVE is now entering the “science verification” phase. During this phase, the instrument’s capabilities will be tested to ensure its ability to address the scientific questions it was designed for. Once this phase is complete, WEAVE will commence its observational campaign, which is expected to span at least five years. Over this period, it will provide over 30 million spectra for more than 10 million astronomical objects.

 

WEAVE operations are divided into eight surveys, involving more than 500 astronomers from 11 different countries:

  • The “WEAVE Galactic Archaeology” survey aims to measure the metallicity (the abundance of heavy elements compared to hydrogen) of 3 million stars in the Main Sequence turn-off and red giants, as well as detailed chemical abundances of 1.5 million objects divided into four sub-surveys.
  • The “Stellar, Circumstellar, and Interstellar Physics” survey focuses on observing young stars, massive stars, and nebulae along the Galactic plane to gain a comprehensive understanding of the star formation process in our Galaxy.
  • The “White Dwarfs Survey” is dedicated to studying a sample of 50,000 white dwarfs.
  • The “WEAVE-Apertif Survey” will provide low-resolution spectra for 400 galaxies and high-resolution spectra for an additional 100 galaxies.
  • The “WEAVE Galaxy Cluster Survey” will concentrate on galaxy clusters to investigate stellar populations, properties of ionized gas, and the dynamics of stars and gas within galaxies in clusters.
  • The “Stellar Population at Intermediate Redshift Survey” aims to study the properties and dynamics of approximately 25,000 galaxies with redshifts between 0.3 and 0.7.
  • The “WEAVE-LOFAR Survey” will obtain spectra for around one million extragalactic sources selected based on activity diagnostics provided by the LOFAR Two-metre Sky Survey (LoTSS).
  • The “WEAVE-QSO” survey will explore the intergalactic medium at redshifts z > 2.1 through observations of a sample of 40,000 quasars.

The paper “The wide-field, multiplexed, spectroscopic facility WEAVE: Survey design, overview, and simulated implementation” by S. Jin (Oxford Astrophysics, University of Oxford), recently published in the journal “Monthly Notices of the Royal Astronomical Society,” provides a detailed description of WEAVE and the eight surveys, the data reduction pipeline, the observing strategy, and the simulator used during the extensive mission preparation phase. Among the long list of coauthors of this paper is the astronomer M. G. Guarcello from INAF – Astronomical Observatory of Palermo, who is associated with the “Stellar, Circumstellar, and Interstellar Physics” survey.

 

The figure (click here to view the entire image) illustrates:

  • Panel a) A diagram depicting the deployment of fibers across the field of view.
  • Panel b) An example of observations of the WEAVE Nearby Clusters survey: observations made using the IFU and fibers targeting dwarf galaxies in the galaxy cluster A2152. Examples of non WEAVE data providing dynamics maps and spectra of the galaxies are shown in the bottom and top panels, respectively.
  • Panel c) An example of a typical galaxy that will be observed by the WEAVE-Apertif survey, which is the galaxy UGC9837 observed with the large field IFU.
  • Panel d) The footprint of the observations of the Galactic plane for the “Stellar, Circumstellar, and Interstellar Physics” survey. Fields marked in yellow will be observed at medium resolution, while those in blue will be observed at high resolution.

 

Mario Giuseppe Guarcello  ( follow mariospiegacose) ( mariospiegacose) ( follow mariospiegacose)

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