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Title: Stacking the invisibles: A guided search for low-luminosity Milky Way satellites

Almost every known low-luminosity Milky Way dwarf spheroidal (dSph) satellite galaxy contains at least one RR Lyrae star. Assuming that a fraction of distant (60 < d {sub helio} < 100 kpc) Galactic halo RR Lyrae stars are members of yet to be discovered low-luminosity dSph galaxies, we perform a guided search for these low-luminosity dSph galaxies. In order to detect the presence of dSph galaxies, we combine stars selected from more than 123 sightlines centered on RR Lyrae stars identified by the Palomar Transient Factory. We find that this method is sensitive enough to detect the presence of Segue 1-like galaxies (M{sub V}=−1.5{sub −0.8}{sup +0.6}, r{sub h} = 30 pc) even if only ∼20 sightlines were occupied by such dSph galaxies. Yet, when our method is applied to the Sloan Digital Sky Survey Data Release 10 imaging catalog, no signal is detected. An application of our method to sightlines occupied by pairs of close (<200 pc) horizontal branch stars, also did not yield a detection. Thus, we place upper limits on the number of low-luminosity dSph galaxies with half-light radii from 30 pc to 120 pc, and in the probed volume of the halo. Stronger constraints on the luminositymore » function may be obtained by applying our method to sightlines centered on RR Lyrae stars selected from the Pan-STARRS1 survey, and eventually, from the Large Synoptic Survey Telescope. In Appendix A, we present spectroscopic observations of an RRab star in the Boötes 3 dSph and a light curve of an RRab star near the Boötes 2 dSph.« less
Authors:
; ; ; ; ;  [1] ; ;  [2] ; ; ;  [3] ;  [4]
  1. Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States)
  2. Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany)
  3. Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States)
  4. Benoziyo Center for Astrophysics, Weizmann Institute of Science, 76100 Rehovot (Israel)
Publication Date:
OSTI Identifier:
22370535
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 793; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; DETECTION; DWARF STARS; GALAXIES; LUMINOSITY; MILKY WAY; SATELLITES; STARS; TELESCOPES; TRANSIENTS; VISIBLE RADIATION