The QUEST RR Lyrae Survey. II. The Halo Overdensities in the First Catalog

By A. K. Vivas, R. Zinn. 2006

133 citations recorded by the source corpus.

The first catalog of the RR Lyrae stars (RRLSs) in the Galactic halo by the Quasar Equatorial Survey Team (QUEST) has been searched for significant overdensities that may be debris from disrupted dwarf galaxies or globular clusters. These RRLSs are contained in a band ∼2.°3 wide in declination that spans ∼165° in right ascension and lie ∼4 to ∼60 kpc from the Sun. Away from the major overdensities, the distribution of these stars is adequately fitted by a smooth halo model, in which the flattening of the halo decreases with increasing galactocentric distance (as reported by Preston et al.). This model was used to estimate the "background" of RRLSs on which the halo overdensities are overlaid. A procedure was developed for recognizing groups of stars that constitute significant overdensities with respect to this background. To test this procedure, a Monte Carlo routine was used to make artificial RRLS surveys that follow the smooth halo model but with Poisson-distributed noise in the numbers of RRLSs and, within limits, random variations in the positions and magnitudes of the artificial stars. The 104 artificial surveys created by this routine were examined for significant groups in exactly the same way as the QUEST survey. These calculations provided estimates of the frequencies with which random fluctuations produce significant groups. In the QUEST survey there are six significant overdensities that contain six or more stars and several smaller ones. The small ones and possibly one or two of the larger ones may be artifacts of statistical fluctuations, and they need to be confirmed by measurements of radial velocity and/or proper motion. The most prominent groups are the northern stream from the Sagittarius dwarf spheroidal galaxy and a large group in Virgo, formerly known as the "12.4 hr clump," which Duffau and coworkers have recently shown to contain a stellar stream (the Virgo stellar stream). Two other groups lie in the direction of the Monoceros stream and at approximately the right distance for membership. Another group is related to the globular cluster Palomar 5.

Subfields: Astronomy and Astrophysics, Computational Mechanics

View Paper: https://www.semanticscholar.org/paper/a09925c3cf73cbfa01ec7731e8b3a2f74dc9207a

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Computational Mechanics

Citations in the corpus

Cosmological simulations of the formation of the stellar haloes around disc galaxies (2011, unknown): “…1985; Preston, Shectman Beers 1991; Wetterer & McGraw 1996; Ivezić et al. 2000; Morrison et al. 2000; Yanny et al. 2000; Chiba & Beers 2000; Chen et al. 2001; Siegel et al. 2002; Vivas & Zinn 2006; Bell et al. 2008; Juŕıc et al. 2008; Smith et al. 2009; Sesar et al. 2011; Deason et al. 2011b).”
THE CASE FOR THE DUAL HALO OF THE MILKY WAY (2011, methodology): “Examples include analyses of RR Lyraes based on the data from the QUEST survey (Vivas & Zinn 2006), as well as from the LONEOS sample (Miceli et al. 2008).”
The Galaxy in Context: Structural, Kinematic, and Integrated Properties (2016, background): “…been extensively studied using several tracers for which good distances can be determined, including RR Lyrae stars (typical distance accuracy ∼7%, Vivas & Zinn 2006), blue horizontal branch (BHB) stars (∼5%, Belokurov et al. 2013), red giant branch (RGB) stars (∼16%, Xue et al. 2014), and…”
The Milky Way Tomography with SDSS. II. Stellar Metallicity (2008, background): “…et al. 2000; Yanny et al. 2000; Vivas et al. 2001; Newberg et al. 2002; Gilmore, Wyse & Norris 2002; Majewski et al. 2003; Duffau, Zinn & Vivas 2006; Vivas & Zinn 2006; Grillmair 2006ab; Belokurov et al. 2006, 2007; Bell et al. 2007; Jurić et al. 2008) have deeply shaken this standard view.”
THE SHAPE OF THE INNER MILKY WAY HALO FROM OBSERVATIONS OF THE PAL 5 AND GD–1 STELLAR STREAMS (2016, methodology): “Measurements of the distance to the Pal 5 cluster range from 20.9 kpc to 23.2 kpc (Harris 1996; Vivas & Zinn 2006; Dotter et al. 2011) and we conservatively assume a flat prior on the distance between 20 kpc and 24 kpc.”
The Haunted Halos of Andromeda and Triangulum: A Panorama of Galaxy Formation in Action (2007, methodology): “Similarly, analysis of the RRLyrae sample of Vivas & Zinn (2006) yielded ρ(r) ∝ r−2.7±0.1 or ρ(r) ∝ r−3.1±0.1, depending on model assumptions of the shape of the halo.”
Substructure revealed by RR Lyraes in SDSS Stripe 82 (2009, methodology): “Variable stars of particular interest are RR Lyraes, which have often been used to identify Galactic substructure – for example, in studies of the Sagittarius Stream (Ivezić et al. 2000; Vivas et al. 2004; Keller et al. 2008), and the Monoceros and Virgo Overdensities (Vivas & Zinn 2006; Keller, Da”
Galactic stellar haloes in the CDM model (2009, methodology): “…of 100 kpc using luminous tracers such as RR Lyraes, blue horizontal branch stars, metal-poor giants and globular clusters (e.g. Oort E-mail: a.p.cooper@durham.ac.uk 1926; Baade 1944; Eggen, Lynden-Bell & Sandage 1962; Searle & Zinn 1978; Yanny et al. 2000; Vivas & Zinn 2006; Morrison et al. 2009).”
LIGHT CURVE TEMPLATES AND GALACTIC DISTRIBUTION OF RR LYRAE STARS FROM SLOAN DIGITAL SKY SURVEY STRIPE 82 (2009, methodology): “Following the discussion by Vivas & Zinn (2006) (see their Section 4), we adopt σMV = √ (σ [Fe/H] MV )2 + (∆MevV ) 2 = 0.1 mag as the uncertainty in absolute magnitude, where σ [Fe/H] MV = 0.07 mag is the uncertainty due to metallicity dispersion (σ[Fe/H] = 0.3 dex, Ivezić et al. 2008), and ∆MevV…”
PROBING THE OUTER GALACTIC HALO WITH RR LYRAE FROM THE CATALINA SURVEYS (2012, methodology): “…Arizona, Department of Planetary Sciences, Lunar and Planetary Laboratory, 1629 E. University Blvd, Tucson AZ 85721, USA 1http://crts.caltech.edu/ giants (Majewski et al. 2003) with portions of the stream being studied using RR Lyrae (RRL, Vivas & Zinn 2006; Miceli et al. 2008; Sesar et al. 2010).”
STRUCTURE AND KINEMATICS OF THE STELLAR HALOS AND THICK DISKS OF THE MILKY WAY BASED ON CALIBRATION STARS FROM SLOAN DIGITAL SKY SURVEY DR7 (2009, methodology): “From the QUEST RR Lyrae Data (which cover basically the same distance range as the Ivezić et al. sample), Vivas & Zinn (2006) obtained values for the derived slope between −2.5 ± 0.1 and −3.1 ± 0.1, depending on the adopted level of flattening and local density.”