The Shape and Profile of the Milky Way Halo as Seen by the Canada-France-Hawaii Telescope Legacy Survey
- Creators
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Sesar, Branimir
- Jurić, Mario
- Ivezić, Željko
Abstract
We use Canada-France-Hawaii Telescope Legacy Survey data for 170 deg^2, recalibrated and transformed to the Sloan Digital Sky Survey ugri photometric system, to study the distribution of near-turnoff main-sequence stars in the Galactic halo along four lines of sight to heliocentric distances of ~35 kpc. We find that the halo stellar number density profile becomes steeper at Galactocentric distances greater than R_(gal) ~ 28 kpc, with the power-law index changing from n_(inner) = –2.62 ± 0.04 to n_(outer) = –3.8 ± 0.1. In particular, we test a series of single power-law models and find them to be strongly disfavored by the data. The parameters for the best-fit Einasto profile are n = 2.2 ± 0.2 and R_e = 22.2 ± 0.4 kpc. We measure the oblateness of the halo to be q ≡ c/a = 0.70 ± 0.01 and detect no evidence of it changing across the range of probed distances. The Sagittarius stream is detected in the l = 173° and b = –62° direction as an overdensity of [Fe/H] ~ -1.5 dex stars at R_(gal) ~ 32 kpc, providing a new constraint for the Sagittarius stream and dark matter halo models. We also detect the Monoceros stream as an overdensity of [Fe/H] > -1.5 dex stars in the l = 232° and b = 26° direction at R_(gal) ≲ 25 kpc. In the two sight lines where we do not detect significant substructure, the median metallicity is found to be independent of distance within systematic uncertainties ([Fe/H] ~ -1.5 ± 0.1 dex).
Additional Information
© 2011 American Astronomical Society. Received 2010 November 16; accepted 2011 February 2; published 2011 March 16. B.S. thanks NSF grant AST-0908139 to J. G. Cohen and NSF grant AST-1009987 to S. R. Kulkarni for partial support. Ž.I. acknowledges support by NSF grants AST-0707901 and AST-1008784 to the University of Washington, by NSF grant AST-0551161 to LSST for design and development activity, and by the Croatian National Science Foundation grant O-1548-2009. M.J. acknowledges support by NASA through Hubble Fellowship grant HF-51255.01-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. Partial support for this work was provided by NASA through a contract issued by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. Based on observations obtained with MegaPrime/ MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada–France–Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Science de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at TERAPIX and the Canadian Astronomy Data Centre as part of the Canada–France–Hawaii Telescope Legacy Survey, a collaborative project of NRC and CNRS.Attached Files
Published - Sesar2011p13757Astrophys_J.pdf
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Additional details
- Eprint ID
- 23604
- Resolver ID
- CaltechAUTHORS:20110509-110832122
- AST-0908139
- NSF
- AST-1009987
- NSF
- AST-0707901
- NSF
- AST-1008784
- NSF
- AST-0551161
- NSF
- O-1548-2009
- Croatian National Science Foundation
- HF-51255.01-A
- NASA Hubble Fellowship
- Created
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2011-05-09Created from EPrint's datestamp field
- Updated
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2021-11-09Created from EPrint's last_modified field