A BAYESIAN APPROACH TO LOCATING THE RED GIANT BRANCH TIP MAGNITUDE. I

Journal Article · Thu Oct 20 00:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/740/2/69; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21587381

Conn, A R; Parker, Q A; Zucker, D B ^[1]; Lewis, G F ^[2]; Ibata, R A ^[3]; McConnachie, A W ^[4]; Martin, N F ^[5]; Irwin, M J ^[6]; Tanvir, N ^[7]; Fardal, M A ^[8]; Ferguson, A M. N. ^[9]

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1. Department of Physics and Astronomy, Macquarie University, Sydney 2109 (Australia)
2. Institute of Astronomy, School of Physics, A29, University of Sydney, Sydney, NSW 2006 (Australia)
3. Observatoire Astronomique, Universite de Strasbourg, CNRS, 67000 Strasbourg (France)
4. NRC Herzberg Institute of Astrophysics, Victoria, British Columbia V9E 2E7 (Canada)
5. Max-Planck-Institut fuer Astronomie, D-69117 Heidelberg (Germany)
6. Institute of Astronomy, University of Cambridge, Cambridge CB3 0HA (United Kingdom)
7. Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH (United Kingdom)
8. Department of Astronomy, University of Massachusetts, LGRT 619-E, Amherst, MA 01003-9305 (United States)
9. Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh EH9 3HJ (United Kingdom)

We present a new approach for identifying the tip of the red giant branch (TRGB) which, as we show, works robustly even on sparsely populated targets. Moreover, the approach is highly adaptable to the available data for the stellar population under study, with prior information readily incorporable into the algorithm. The uncertainty in the derived distances is also made tangible and easily calculable from posterior probability distributions. We provide an outline of the development of the algorithm and present the results of tests designed to characterize its capabilities and limitations. We then apply the new algorithm to three M31 satellites: Andromeda I, Andromeda II, and the fainter Andromeda XXIII, using data from the Pan-Andromeda Archaeological Survey (PAndAS), and derive their distances as 731{sup (+5)+18}{sub (-4)-17} kpc, 634{sup (+2)+15}{sub (-2)-14} kpc, and 733{sup (+13)+23}{sub (-11)-22} kpc, respectively, where the errors appearing in parentheses are the components intrinsic to the method, while the larger values give the errors after accounting for additional sources of error. These results agree well with the best distance determinations in the literature and provide the smallest uncertainties to date. This paper is an introduction to the workings and capabilities of our new approach in its basic form, while a follow-up paper shall make full use of the method's ability to incorporate priors and use the resulting algorithm to systematically obtain distances to all of M31's satellites identifiable in the PAndAS survey area.

• OSTI ID: 21587381
• Journal Information: Astrophysical Journal, Vol. 740, Issue 2; Other Information: DOI: 10.1088/0004-637X/740/2/69; Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ALGORITHMS
DISTANCE
GALAXIES
RED GIANT STARS
SATELLITES
GIANT STARS
MATHEMATICAL LOGIC
STARS