Astro seminar guest Gerry Williger – The GALEX Extragalactic Spectral Database

Gerry Williger from University of Louisville will give a talk on “The GALEX Extragalactic Spectral Database”

Abstract:

We present results from a project to categorize and collect complementary multiband data for approximately 11,000 extragalactic sources in 211 GALEX spectroscopic fields which overlap the Sloan Digital Sky Survey (SDSS). The project yields a useful searchable database for the scientific exploitation of GALEX UV spectra (R~100-200) of extragalactic sources. For all extragalactic sources (known or classified by us) with GALEX spectra, we have assembled complementary images and photometry in FUV+NUV from GALEX, in ugriz from the SDSS, in JHK from the Two Micron All Sky Survey (2MASS) and in W1-W4 from the Wide-field Infrared Survey Explorer (WISE), and created spectral energy distributions (SEDs). We have also logged SIMBAD and SDSS object classification, redshift and angular size information, and provide some indication of spectral data quality, since it largely varies across the sample and even across the wavelength range of individual spectra, owing to the grism observing strategy (Bianchi et al. 2018, Astrophys. Space Sci., 363, 56).

The UV spectral database consists of 1820 quasars, 2274 star-forming galaxies, 6327 quiescent spirals and 386 ellipticals. The mean redshifts for quasars, star-forming galaxies, quiescent spirals and ellipticals are 0.99, 0.07, 0.35 and 0.05 respectively. We will show representative spectra, SEDs and color-magnitude diagrams. The database (Pritchard et al., in preparation) will be made publicly available from the Mikulski Archive for Space Telescopes (STScI’s MAST) as a High-Level Science Product (HLSP), as well as from Vizier.