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Published byFrederica Loreen Edwards Modified over 9 years ago
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Similarity of DM/DE and TeVeS HongSheng Zhao @SUPA
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ΛCDM WDM Tuned DM-DE (~ Tuned TeVeS μ )
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I.Much ado about mu µ in disk galaxies with Famaey (Brussels), Angus (SUPA), Gentile (NMSU), Nipoti, Londrillo, Ciotti (Bologna) & high-z elliptical lensing galaxies with Bacon, Taylor, Horne (SUPA), Shan (Beijing) in cosmology with Skordis (Perimeter), Mota (Oslo)
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III. TeVeS (Bekenstein 2004) Einstein-like equations for g , U , scalar by varying the action w.r.t. each of these fields In a quasi-static system with a weak gravitational field, N + : dτ 2 = (1-2 ) dt 2 -(1+2 ) ( dx 2 + dy 2 + dz 2 ) where obeys a B-M equation, and plays the role of the dark matter potential (dynamics and lensing are governed by the same physical metric g)
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Define y = (3k’ 2 /a 0 2 ) Y, Y=(g -U U ) , , where k’ k/ 4 is a parameter of the theory y ( ) 2 >0 in quasi-static situation y -( / t) 2 <0 in cosmology Equation for the scalar field in a quasi-static system . [ s (y) ] = 4 G (similar to B-M) In spherical symmetry gravity: s = / (1- )
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Analogy: as dielectric and as inertia Conservative Field g or E = -▼Φ = d 2 x/dt 2 Poisson equation ρ = ▼·D or ▼·g N –Electric displacement D = μ E = E + PolarisationField –TeVeS-like theory g N = μ g = g - ScalarField Newtonian F = m inertia g, m inertia = m
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Scalar field in TeVeS resembles DM Scalar field (Polarisation Halo of luminous baryon 1-to-1 gravity) ~ tuned Dark Halo surrounding baryons NFW profile? µ?
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I. Constraining the law of (Zhao & Famaey 2006, ApJ letters) Standard (I): (x) = x / (1+x 2 ) 1/2 Exponential: (x) = 1 - e -x Bekenstein toy model: (x) = [(1+4x) 1/2 -1] / [(1+4x) 1/2 + 1] Simple (III): (x) = x / (1+x) s (g s ) = /(1- ) g s = g - g (g)
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External Field Effect
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Milgrom’s standard µ = x/(1+x 2 ) 1/2 Excellent description of data! –Deviation capped ~ a0. –Fast transition of law from Newtonian solar system into non- Newtonian outer galaxy. But … incompatible with TeVeS!
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Fast transitions (implied by data & mu-standard) challenging for TeVeS Less freedom in mu than in 1-field MOND. –Bekenstein mu excluded by RC data. Scalar field must increase from galaxies (a0) to solar system –untailored mu will overrun Pioneer limit (<10a0).
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Problems with earlier laws of Milgrom’s standard -law too sharp, – leads to multi-valued TeVeS L and problems with external field. Bekenstein’s too gradual – unlike in real galaxy RC.
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The standard and exponential functions are excluded (multi-valued), but good to fit RC’s Bekenstein’s toy is ok in TeVeS, but poor fit to the TVC of the Milky Way (Famaey & Binney 2005), same conclusion in spiral galaxy NGC 3198
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A narrow range of mu is allowed alpha-model in Angus, Famaey, Zhao [Poster] & Gentile, Famaey, Zhao [Poster] Curl-field correction [Nipoti’s talk]
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The Simple Function = x / (1+x) = / (a 0 + ) gives a good fit to RC’s and corresponds to a plausible TeVeS s (y) Simple ’s corresponding scalar field function is s = / (a 0 - α ), α=1 (Zhao-Famaey) = s / (1+ s ) = / a 0
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Deeper Physics Beyond Simplicity? In spherical symmetry: Newtonian F N = m inertia g, m inertia = m ExtraForce |F s |= m inertia a 0, with a 0 ~c
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Test mu where it is not made for: Elliptical Lenses, SNe, Cosmology!
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Metric of Homogeneous Universe Hubble expansion in TeVeS
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Scalar field density tracks matter density
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As good as ΛCDM, but no Λ!
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Updating Scores LCDM TeVeS Solar System ? ? Tides on Globulars & dSph Rot. curves HSB/LSB Lensing by Ellipticals/Clusters SNIa/CMB
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