Marcel S. Pawlowski - Astronomer & Black and White Photographer
  • Home
  • About
  • Research
    • Publications
    • Presentations
    • Press
    • Movies
  • Photography
  • News
  • Contact
Illustration of SDSS survey footprint shape (red points) and region in which all brighter classical satellites would have been found by now (blue points).

New Paper: The alignment of SDSS satellites with the VPOS: effects of the survey footprint shape

Posted On November 19, 2015 By Marcel In News /  

One frequent concern in regard to the Vast Polar Structure (VPOS) of satellite galaxies around the Milky Way – the plane-like distribution of satellite galaxies which mostly co-orbit – is that the fainter satellite galaxies do not provide much information. It is often argued that due to the preference surveys such as the Sloan Digital Sky Survey (SDSS) give to the regions close to the Milky Way poles, any satellite galaxy discovered by them has to align with the VPOS. However, this argument, often made in reaction to my talks on the matter, has never been quantitatively tested, yet alone shown to be correct. This is why I decided to check it myself, which resulted in my most-recent (and first single-author, yay!) paper: “The alignment of SDSS satellites with the VPOS: effects of the survey footprint shape” (accepted for publication in MNRAS, preprint: arXiv:1511.05557*).

My results: That the satellites discovered in SDSS align as well as observed with the plane defined by the 11 classical satellites is indeed very unlikely if the satellites were drawn from an isotropic distribution. This analysis considers the exact SDSS survey footprint (my algorithm essentially follows all the SDSS observing runs when building the mock satellite distributions). Overall, the significance of the VPOS is high (higher than that of the satellite plane discovered around the Andromeda Galaxy!), and the faint satellites discovered in SDSS do add to this (from about 4 to 5σ). Furthermore, I estimate which fraction of the Milky Way satellites considered in this study (for simplicity only the 11 classical and 16 SDSS satellites) might still be part of an isotropic distribution. This was motivated by the plane around Andromeda, which consists of only about 50% of the known satellite dwarf galaxies. I find that for the Milky Way, an isotropic contribution of more than 50% off-plane satellites can be excluded at high significance, and the expected number is between 2 and 6 out of 27.

The other benefit of this paper is that I now have an algorithm to model the SDSS (and other) survey footprints, such that I can apply them to cosmological simulations next. This will allow me to perform more detailed near-field cosmology tests of what is now called the Satellite Plane Problem of ΛCDM.

 

*: As a funny coincidence the arXiv ID 05557 is easy to remember for me: it is the 7th first-author paper I have written at CWRU, where my office has number 555. 😉

Tags:
arXivdwarf galaxiesnew papersatellite galaxiessatellite plane problemSDSSsurveyVast Polar StructureVPOS
New job starting this Fall
New Paper: The new Milky Way satellites: alignment with the VPOS and predictions for proper motions and velocity dispersions

Archives

  • July 2022
  • April 2022
  • March 2022
  • December 2021
  • November 2021
  • September 2021
  • August 2021
  • May 2021
  • December 2020
  • October 2020
  • September 2020
  • June 2020
  • May 2020
  • January 2020
  • November 2019
  • October 2019
  • March 2019
  • November 2017
  • October 2017
  • September 2017
  • June 2016
  • April 2016
  • March 2016
  • November 2015
  • May 2015
  • December 2014
  • July 2014
  • June 2014
  • May 2014
  • April 2014
  • February 2014
  • November 2013
  • July 2013
  • March 2013
  • January 2013
  • May 2012
  • April 2012
  • March 2012
  • August 2011
  • July 2011
  • June 2011
  • February 2011
  • January 2011
  • November 2010
  • August 2010

Meta

  • Log in
All rights reserved.
  • Impressum