-
20
-
-
0039820966
-
-
S. S. Holt, F. Verter, AIP Conf. Proc. No. 278, AIP, New York, 87, J. Binney, ibid. p.
-
(1993)
Back to the Galaxy,
, pp. 98
-
-
Blitz, L.1
-
21
-
-
84927492738
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NASA/GSFC Report
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(1994)
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Dwek, E.1
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25
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0002937430
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ibid., Taking a smaller value for Σlum would allow for larger Σvar and hence larger τbulge; however, taking Σlum=0 only increases τbulge by 0.3×10-6.
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(1991)
, vol.376
, pp. L9
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Kuijken, K.1
Gilmore, G.2
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26
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84927482081
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Such a model (referred to as a Mestel disk [c13]) produces a flat rotation curve in the plane of the galaxy; however, in order to account for a rotation velocity of 220 km s–1, a local surface mass density of 220 M⊙ pc–2 is required. P. Sackett has recently revisited these models, because a thin Mestel disk ( h∼0.3 kpc) whose local surface density is about 220M⊙ pc–2 can (i) marginally account for the bulge rate, (ii) marginally account for the LMC rate, and (iii) produce a flat rotation curve ( v=220 km s–1) in the galactic plane without a halo. However, such a model would not produce a flat rotation curve outside the galactic plane nor would it explain the warping of the disk and the flaring of neutral gas; moreover, it is in severe conflict with kinematic studies that indicate Σtot(1 kpc) is at most 100M⊙ pc–2 [c23].
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29
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84927498350
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Report No. astro-ph/9501068.
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Rix, H.1
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31
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84927500165
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Our expression for τ when applied to the bulge implicitly assumes that all the mass density in the disk and bulge is available for lensing. However, the bulge lenses are certainly not bright stars., [c29] find that correcting for this is a small effect. To account for the fact that the lenses are unlikely to be bright stars we simply do not include the contribution of the fixed luminous disk to τbulge.
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Zhao1
Spergel2
Rich3
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32
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84927498523
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The range we adopt for τLMC is the 95% confidence range derived from the likelihood function based upon three events assuming Poisson statistics. However, the issue of uncertainties is far more complicated and the true 95% confidence range is probably larger; see, Report No. astro-ph/9410052. For example, the measured optical depth τMEAS=(π/4E)Σit^i/ɛi, where the sum i runs over events, t^i is the duration of event i, and ɛi is the “efficiency” of detecting an event of duration t^i. The MACHO efficiency drops significantly for t^i≪10 days and τLMC could be larger than reported due to short duration events. However, because of the null results of the EROS CCD search for short-duration events and the MACHO spike analysis it seems unlikely that this is the case.
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Gould, A.1
Han, C.2
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33
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84927496671
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References [c8 c16]
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-
-
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36
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84927503044
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Princeton Observatory Report No. POP-573
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(1994)
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Paczynski, B.1
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39
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12044249178
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In fact, A. de Rujula et al., (Report No. astro-ph/9408099) have raised the question of where the brown dwarf stars are.
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(1994)
Astrophys. J.
, vol.435
, pp. L51
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Bahcall, J.1
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40
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84927465759
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Reports No. astro-ph/9411016 and No. astro-ph/9411018.
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De Paolis, F.1
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