# Presentation: 444795

## Astrophysical Constraints on Dark Matter Candidate

- Gamma-Ray Group Science Discussion Seminer, March 31, 2004
-                                                                                  by Yasushi Ikebe

- - CDM halo profile models
- - Comparison with observations
- - Emerging theory on self interacting dark matter (SIDM)

## King model

- Density

- R/Rc

- Density

- Self gravitating system of collisionless particles with
- lowered isothermal distribution function

- Michie 1963, MNRAS, 125, 127
- Michie, & Bödenheimer 1963, MNRAS, 126, 269
- King 1966, AJ, 71, 64

- 0[1+(r/rc)2]-1.5

- gives good approximation out to ~3 rc

## King model worked find with X-ray clusters

- Isothermal -model

*Einstein* IPC
- Jones & Forman 1984, ApJ, 276, 38

- Cooling Flow

- Allen & Fabian 1994, MNRAS, 269, 409

*ROSAT* PSPC/ Centaurus cluster

## ASCA observations show:

- - No Cooling Flow

- - Mass profile has larger central mass concentration than
-   King profile, being consistent with NFW model

- Ikebe et al. 1999, ApJ, 525, 58

- King profile

## NFW model

- Hoeft, Muecket, & Gottloeber
- 2004, ApJ, 602, 169

- Nararro,  Frenk, & White, 1995, MNRAS, 275, 720
-                                            1996, ApJ, 462, 563

*Universal* density profile

- crit c (r/rs)-1 (1+r/rs)-2

- Velocity dispersion profile

## Another universal profile

- Fukushige & Makino, 1997, ApJ, 477, L9

- Moore et al. 1998, ApJ, 499, L5

- Ghigna et al. 2000, ApJ, 544, 616

- crit c (r/rs)-1.5 [1+(r/rs)-1.5]-1

- Steeper than r-1

## More N-body Simulations

- Jing & Suto, 2000, ApJ, 529, L69

- Central exponent = - 1.1 ~  -1.5

- Power et al. 2003, MNRAS, 338, 14

- No asymptotic slope is derived
- -1.2 at 0.5% of virial radius

- CDM predicts the slope of -1 ~ -1.5

##               Contradiction to CDM model

-               Contradiction to CDM model
- 1: rotation curves of dwarf spiral galaxies

- Burkert 1995, ApJ, 447, L25

- Moore et al. 1999, MNRAS, 310, 1147

- 0 (1+r/r0)-1 [1+(r/r0)2]-1

- Mass

- Circular velocity

- Moore model

- NFW model

## Contradiction to CDM model

- 2: substructure abundance

- Moore et al. 1999, ApJ, 524, L19

## Self-Interacting Dark Matter (SIDM)

- Yoshida et al. 2000, ApJ, 544, L87

- Non-zero cross section, DM -> collisions scatter particles out of the center
- e.g. Spergel & Steinhardt 2000, Phys Rev. Lett.,84,3760
- Davé et al. 2001, ApJ, 547, 574

- Density

- Collision count

- Number of subhalos

## Constraints on DM

- 1. From DM density profile

- Gravitational lenses:
-            Miralda-Escude, 2002, ApJ, 564, 60
-            Wyithe et al. 2001, ApJ, 555, 504
-            Meneghetti et al. 2001, MNRAS, 325, 435

- X-ray observations:
-           Arabadjis, Bautz, & Garmire, 2002, ApJ, 572, 66
-           Ikebe & Böhringer, 2003, ApJ, submitted

- Rotation curve of dwarf galaxies:
-           e.g. Firmani et al. 2001, MNRAS, 321, 713

## ∫

- ng  =  n0       exp   -                        dR

- GmpM
- kBTgR2

- T0
- Tg

- R
- 0

- [            ]

- Method 1

- Method 2

- X-ray observation

- Modeling the total mass profile

- Fit to data

## Abell 1795

- XMM/EPIC

## Constraints on DM

- Constraints on DM

- 2. DM  cannot be too large

- Constraints from the growth of supermassive black holes:
- The larger the cross-section is, the larger the accreation rate is.
-  (Ostriker 2000, Phys. Rev. Lett. 84, 5258;
-    Hennawi & Ostriker 2002, ApJ, 572, 41)

- Survival of galactic subhalos:
- Heat transfer from cluster DM evaporate galactic subhalos.
- (Gnedin & Ostriker, 2001, ApJ, 561, 61)

## WIMPs    axions

- Mirror matter
-      Mohapatra, Nussinov, & Teplitz, 2002, Phys. Rev. D, 66, 063002

*Q*-Ball
-     Kusenko & Steinhardt, 2001, Phys. Rev. Lett. 87, 141301

- Candidates for SIDM

## But don't worry. They might be wrong.

- 1. Revisit to the density profile measurement from the rotation curves

- The current data may not be sufficient to put any meaningful constraints
- on the dark matter density profiles, due to
-  -  beam smearing,
-  -  uncertain stellar mass-to-light ratio,
-  -  unknown inclination angle,
-  -  degeneragy of the fitting parameters, etc.
- The dark matter density profile in dwarf galaxies are consistent
- with CDM halo models with cuspy core

- Van den Bosch et al. 2000, ApJ, 119, 1579
- van den Bosch, & Swaters 2001, MNRAS, 325, 1017

## But don't worry. They might be wrong.

- Stoehr et al. 2002, MNRAS, 335, L84
- Hayashi et al. 2003, ApJ, 584, 541

- 2. Revision on the satellites' mass estimate:

- Hayashi et al.

- Vmax/V200

- N(>Vmax)

- Result by Moore et al. 1999
- derived with an isothermal assumption