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|Title:||Limits on the local dark matter density|
Read, J. I.
|Publisher:||Oxford University Press (OUP)|
|Citation:||Monthly Notices of the Royal Astronomical Society , 2011, 416 (3), pp. 2318-2340|
|Abstract:||We revisit systematics in determining the local dark matter density ρdm from the vertical motion of stars in the solar neighbourhood. Using a simulation of a Milky Way like galaxy, we determine the data quality required to detect ρdm at its expected local value. We introduce a new method for recovering ρdm that uses moments of the Jeans equations, combined with a Markov chain Monte Carlo technique, to marginalize over the unknown parameters. Given sufficiently good data, we show that our method can recover the correct local dark matter density even in the face of disc inhomogeneities, non-isothermal tracers and a non-separable distribution function. We illustrate the power of our technique by applying it to Hipparcos data. We first make the assumption that the A- and F-star tracer populations are isothermal. This recovers ρdm= 0.003+0.009− 0.007 M⊙ pc−3 (ρdm= 0.11+0.34− 0.27 GeV cm−3, with 90 per cent confidence), consistent with previous determinations. However, the vertical dispersion profile of these tracers is poorly known. If we assume instead a non-isothermal profile similar to that of the blue disc stars from SDSS DR-7 recently measured, we obtain a fit with a very similar χ2 value, but with ρdm= 0.033+0.008− 0.009 M⊙ pc−3 (ρdm= 1.25+0.30− 0.34 GeV cm−3 with 90 per cent confidence). This highlights that it is vital to measure the vertical dispersion profile of the tracers to recover an unbiased estimate of ρdm.|
|Rights:||This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2011 the authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. Deposited with reference to the publisher’s archiving policy available on the SHERPA/RoMEO website.|
|Appears in Collections:||Published Articles, Dept. of Physics and Astronomy|
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|MNRAS-2011-Garbari-2318-40.pdf||Published (publisher PDF)||1.8 MB||Adobe PDF||View/Open|
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