the case for modified gravity n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
THE CASE FOR MODIFIED GRAVITY PowerPoint Presentation
Download Presentation
THE CASE FOR MODIFIED GRAVITY

Loading in 2 Seconds...

play fullscreen
1 / 28

THE CASE FOR MODIFIED GRAVITY - PowerPoint PPT Presentation


  • 118 Views
  • Uploaded on

THE CASE FOR MODIFIED GRAVITY. James Binney Oxford University. Outline. MOND as a replacement for DM (Sanders & McGaugh 02) Absence of DM interior to the Sun (Bissantz et al 03, 04) TeVeS Lorentz-covariant MOND (Bekenstein 2004). NGC 3198. Begeman (1987).

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'THE CASE FOR MODIFIED GRAVITY' - materia


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
the case for modified gravity

THE CASE FOR MODIFIED GRAVITY

James Binney

Oxford University

outline
Outline
  • MOND as a replacement for DM (Sanders & McGaugh 02)
  • Absence of DM interior to the Sun (Bissantz et al 03, 04)
  • TeVeS Lorentz-covariant MOND (Bekenstein 2004)
ngc 3198
NGC 3198

Begeman (1987)

modifying gravity
Modifying gravity
  • Modify Newtonian theory at large distances? or at low accelerations?
tully fisher
Deep MOND regime – when µ(x)~x

At large r always enter deep MOND

Tully-Fisher

Sanders & Verheijen

fits to v c r for both lsb hsb galaxies
Fits to vc(r) for both LSB & HSB Galaxies

(Sanders & McGaugh 02)

a0=1.2 10-8 cm s-2

a0~H0c/2π; Λ~3(a0/c)2

slide9

U Maj

Sanders & Verheijen

recover predicted m l values
Recover predicted M/L values

Data: Sanders & Verheijen

Models: Bell & de Jong 01

giant e galaxies
Giant E galaxies

Data:

Romanowsky et al 03

Models:

Milgrom & Sanders 03

Solid: isotropic

dsph galaxies
dSph galaxies

η = Fi/Ft

dm in the mw
DM in the MW?
  • Bissantz & Gerhard (02) Determine near-IR luminosity density from COBE K & L photometry
  • Advances previous work by including spiral structure in disk
  • Bissantz Englmaier & Gerhard (03) study gas flow in Φ obtained with spatially const M/L + quasi-isothermal DM halo
  • Fit M/L, ωbar, ωspiral
  • M/L for stars set by dynamics of non-axisymmetric structure
  • DM halo makes up balance for tangent-velocity curve
bissantz englmaier gerhard
Bissantz Englmaier & Gerhard

CO observed

simulated

bissantz englmaier gerhard 03
Bissantz Englmaier & Gerhard (03)
  • Find ωbar in good agreement solar nhd kinematics
  • With 4 arms get good pattern of ridge lines
  • Vc near sun ~35 km/s below true value unless DM halo with a=10.7 kpc added
  • With (x)=x/(1+x) KhN/KhM=0.95§0.15 (Famaey & B 04)
optical depths
Optical depths

Bissantz & Gerhard (02)

bissantz debattista gerhard 04
Bissantz Debattista & Gerhard (04)
  • Use novel N-body technique to find dynamical model that reproduces Bissantz & Gerhard photometry
  • Adopt M/L, ω normalization from BEG
  • No free parameters in Φ
  • Reproduce proper motions of bulge stars in Baade’s window etc
  • For plausible mass function of stars, reproduce MACHO microlensing event duration distribution
slide22
Conclusion: stars-only MW gives good fits to both optical depth & duration distribution

(ML<,ML>)=(.04,10) or (.075,10)

klypin et al 02
Klypin et al (02)
  • ΛCDM models of MW
  • Adiabatic compression & optional L exchange

No L exchange L exchange

teves
TeVeS
  • Bekenstein (04) presents Lorentz-covariant theory (TeVeS) that reduces to MOND in appropriate limit
slide26
Standard cosmologies
  • Grav. Lensing as if DM present
  • No superluminal modes
slide27
TeVeS important development Link to effective field theory?
  • Can now extend MOND to CMB and large-scale structure
  • If not worse than CDM in these fields, must be favoured theory
  • Then question: significance of Uµ and Φ fields in TeVeS
conclusions
Conclusions
  • MOND has amazing ability to model data taken after it was invented
  • Excellent fits to galaxy rotation curves require M/L(colour) as from SS theory
  • Compelling evidence that negligible DM interior to Sun
  • Now limiting form of Lorentz covariant theory
  • MOND really might be the next great step in physics