# Presentation: 237924

## X-Ray Probes of the Fifth Dimension:Disappearing Dark Matter and Brane-World Cosmology

- G. J. Mathews, P. M. Garnavich - Univ. Notre Dame
- K. Ichiki, T. Kajino, NAO, Japan
- M. Yahiro, U. Ryukyus, Japan
- Workshop on Studies of Dark Energy and Cosmology with X-ray Surveys
- Greenbelt, MD
- Jan. 15-16, 2004

## Cosmological Parameters are Now Known to Unprecedented Precision 

- Now is the time to look to for a deeper understanding
- Brane-World Cosmology

- Baryons -     Ωb = 0.045±0.002
- Dark Matter   -  ΩDM = 0.22±0.01
-     Lightest Supersymmetric Particle?
- Dark Energy -    Ω = 0.73±0.04
-            Quintessence?

## Brane World Cosmology: M-Theory/IIB String theory

- In the low-energy limit, the  heterotic M-theory is 11-dimensional supergravity coupled to two 10-dimensional E8 gauge theories.  (Horava & Witten 1996, NPB, 506)

- Bulk Dimension

-  Six dimensions compactify on each brane. Physical particles/gauge fields are strings trapped on the  branes
-  Gravitons reside in both branes and  bulk

- Brane World Cosmology: M-Theory/IIB String theory

-  There are two smooth 10-dimensional manifolds (10-branes) embedded in a bulk dimension

- m0

## Brane World Cosmology: 

- PRL 83 (1999): The bulk dimension can be large
-  Alternative to KK compactification of the bulk dimension.

- Bulk Dimension

- z

-  Physical particles are trapped on the 3-brane
-  Gravitons reside in both the brane and  bulk

- Brane World Cosmology:
- Randall-Sundrum II Cosmology

-  The universe is described as an effective 3-brane
-  Embedded in a large 5 dimensional anti-deSitter space (AdS5).

- m0

## How do we find evidence for this Fifth Dimension?

- ?

## Disappearing Dark Matter

- K. Ichiki, P. Garnavich, T. Kajino, G. J. Mathews, M. Yahiro,
- PRD, 68, 083518 (2003)

## Matter fields may not be confined 

- Bulk Dimension

- m0

- z

-  Quantizing  massive matter fields in 5 dimensions leads to quasilocalized eigenstates in 4 spatial dimensions
- Particles  with mass can tunnel into the bulk 5th dimension

- Matter fields may not be confined
- to the 3-brane (Dubovsky, Rubakov, Tinyakov (2000)

## Gravity suppressed in the bulk 

- Bulk Dimension

- m0

- z

-   In the bulk: UG ~ [Gm1m0/r2] (R/z)
-   where, R = **k**-1 = curvature radius of bulk
-       = /6M53 ~ 10-4 fm

- Gravity suppressed in the bulk
- (Giddings, Katz & Randall  2002 JHEP)

- G m1m0/r2 on the brane  ,  *ds**2**= -e **{-2****k****|z|}**g**** **dx****dx****  **- dz**2*

- m1

- m0

- Particles in the bulk no longer
- interact with the brane.
- They literally disappear!

## Transfer to the Bulk leads to Modified Cosmic Expansion

- E = “Dark Radiation” or Electric part of the bulk Weyl tensor

## A New Cosmology

## Consequence: More Dark Matter in the Past

-  Early Universe decelerates faster

- 

- 

- 

- 

## X-ray gas fraction in rich clusters should decrease with redshift

- fgas~B/ tot ~ (B/ DM )z=0 exp[ -(t0-t)]

- Ettori, Tozzi & Rotti
- A&A, (2003).
*BeppoSAX *and *Chandra* gravitating mass profiles to z=1.3

## Galaxy Cluster M/L should increase with look-back time

- M/L~DM/B ~ (M/L)z=0 exp[ (t0-t)]

- Bahcall & Comerford
- ApJL, 565, L5(2002)
- 21 clusters out to z=1

## High Z Supernovae

- 

- Supernovae are brighter at very high redshift

- Tonry et al. (2003) astro-ph/0305008

## Microwave Background

-   2 parameter (  fit is equivalent to standard CDM
-   MCMB > Mnow     allowed

## Constraints

- 2 Concordance for 15 < -1< 60 Gyr, DM = 0.160.04

- X-ray

## Dark Energy:

- Bulk Dimension

- m0

- Z

-   The flow of matter back into the 3-brane will appear as spontaneous matter creation
- e.g. H  constant = flow rate into brane
-   This mimics a cosmological constant even for 4 =0

- The flow of particles from the bulk to the brane produces an accelerating cosmology

- m0

- m0

- Kiritsis et al., hep-th/0207060, Tetradis hep-th/0211200

## Conclusions

- Disappearing Dark Matter cosmology is consistent with:
-      Cluster X-ray emitting gas fraction with z
-       SNIa, for  z > 1
-       Increasing cluster M/L ratio with redshift
-        CMB- WMAP
- X-ray survey data with z > 1,  better understanding of the dispersion in fgas would be very helpful to constrain this cosmology and even  provide  the first evidence for a large extra dimension

## General case:  Parametrize T05

-  accelerating cosmology for q < 3
-  Branes are moving/colliding
- Dark Energy is increasing

-  T05 = T05(1)/aq
-     q = 3 Normal matter
-      q = 4 Relativistic matter
-     q = 0 Dark energy

- Scale factor:  a(t) = [a0q/3 + (q/3)C (t -t0)]3/q
-           limq0 a = a0 eC (t -t0)

## Effects of Brane-World Cosmology on the Origin of Matter and Evolution of Galaxies

- Dark Radiation
- Disappearing Matter
- Dark Energy
- Deviations of Gravity

- Time Varying Constants
- Compact Topologies
- Parallel Universes
- Ekpyrotic  Evolution

## Allowed Dark Radiation

**WMAP**

## Disappearing LSP Dark Matter is a likely possibility

- Fermions:
*** **** **m**0** ****m**0**/2****k****)**2gv/****k****-1****[****(gv/****k****+1/2****]**2**)*
- v = vacuum expectation value; g = coupling
*Require    gv/****k****  > 1/2*

- Scalar Particles:
***= ****m**0**3**/****k****2*

*  **Largest ****  for largest m**0**  *

## Dark Radiation in RS II Cosmology

-  *G**AB** = ****5**2** T**AB  **, ****5**2** = 1/2M**5**3**  ,  A,B = (0,1,2,3,**5**)*
*ds**2** = **e **{-2***k***|z|}**** **** **dx****dx****  **- dz**2 *
*T**A**B **(brane)=(****(z)/b)diag(-****-****, -****+p, -****+p, -****+p,**0**)*
*T**A**B **(vacuum)= diag( -****5**, -****5**, -****5**, -****5**, **-****5** )*
- Leads to a new Friedmann equation for cosmic expansion

- Dark Radiation

- GN= 52 2/48π  , 4 = 54 2/12 +3 5 /4

## X-ray gas fraction vs. redshift

- fgas~Mgas/ Mtot ~ (B/ M )
-  LX(1+z)-1/4 /(4πdang2) ~ Mgas2c -3 dang-3 (T) /4πdang2

- Ettori, Tozzi & Rosati , A&A, 398, 879 (2003).
*BeppoSAX *and *Chandra* gravitating mass profiles to z=1.3

## X-ray gas fraction in rich clusters should decrease with redshift

- fgas~~ (B/ M )z=0 exp[ -(t0-t)]

- More Dark Matter at High z