1. Cooperate with X-L. Chen , Q. Yuan, X-J. Bi, Z-Q. Shen
Approaching the Light Side of Dark Matter? --- issues related to dark matter indirect detection
黄 峰
厦 门 大 学
Cooperate with X-L. Chen , Q. Yuan, X-J. Bi, Z-Q. Shen 恩施

2. Outline Introduction Dark Matter and its annihilation signals Summary
1, Non-thermal Sunyaev-Zel'dovich (SZ) effect in Cluster and DSphs with two different Dark Matter model considered
2, Constraints on Leptonic DM with associated Inverse Compton Scattering emission (ICS) and Final State Radiation (FSR) in DSphs
3, Synchrotron Emission in Dwarf Galaxies
Summary

3. Introduction Dominant matter component : non-baryonic matter
Evidence: Rotation Curves, CMB,
BBN, LSS …(gravitational effects)
What’s the particle nature?
—remain a puzzle

4. What is Dark Matter? Leptonic DM (TeV) WIMP: Neutralino (10GeV-TeV)
Well provided theoretically
Phenomenology proposed
WIMP: Neutralino (10GeV-TeV)
Light DM (MeV) 4

5. Further Constraints Other dark halos? Multi-wavelength?
Colafrancesco, IoP/RAS Meeting 2007

6. Colafrancesco, IoP/RAS Meeting 2007
Multi-wavelength?
正负电子源
e^+-:
SZ effect
IC emission
Synchrotron emission
Colafrancesco, IoP/RAS Meeting 2007
正负电子的在不同
的天体系统的传播

7. DM annihilates in Nearby Dark Halos
Other dark halos?
DM annihilates in Nearby Dark Halos
Nearby galaxies clusters:
cluster as the largest bound containers of DM
Dwarf galaxies:
dominated by DM both in central regions and outskirts
close to be a pure dark halo
local group satellites

8. Clusters v.s. Dwarf galaxies
astrophoton.com/dwarf_galaxies.htm
Large Scale
Hot gas
Diffusion irrelevant
Small scale
Lack of gas
Diffusion dominant

10. SZ effect induced by DM Annihilation in Clusters and DSphs

11. SZ effect induced by WIMP in Coma Cluster
m=40GeV
S. Colafrancesco et al.
Astro-ph/
Q. Yuan et al.
Astro-ph/

12. SZ effect induced by LDM in Coma Cluster
<v>(1MeV/m)2~10-30cm3/s
(PRL, 2004, 92, )
511keV

13. Other Clusters

14. number density distribution of electrons in dSphs
SZ~ n_e*T_e
Uncertainty in the description of
equilibrium electrons&positrons distribution

15. Compare to previous work
SZ effect induced by DM self-annihilation
Compare to previous work

16. SZ effect induced by DM self-annihilation
With different
density profile
With Different
diffuse model

17. SZ from DSphs

18. ICS and FSR associated with Leptonic DM annihilation in DSphs

19. Motivation Other Constraints Leptonic DM
eg: S. Profumo et al., arXiv:
Liu et. al., arXiv:

20. ICS and FSR in Nearby Dwarf Halo

21. Observation Constraints
MAGIC：F(E>140GeV) < 1.1d-11 ph /cm^2/s
F(E>140GeV) ~ 9.78d-10 ph NFW
EGRET：F(E>2GeV) < 3.3d-7 /cm^2/s/sr
FERMI: ?

22. Synchrotron emission from Dwarf galaxies

23. Radio emission in dSphs: diffuse and weak
~90% of the total flux is from the central region of 2 degree ~50% is within central 50 arcmin region.
~possible enhancement from sub-halo which survived in the outerskirts
What’s the implication for observation?

24. ATA observation (黄峰，陈学雷，沈志强)
VLA at 4.885GHz in 1979
very center region (4arcmin ) <2mJy
Updated observation required
Diffuse large field view
weak high sensitivity
F.o.V at 1.4GHz: 2.5 degree
42 working antennas
Effective bandwidth :103MHz
6hrs on-source time.
rms: 1.4GHz
Crucial factor: local magnetic field B

25. More distant dSphs: Leo I
Other radio array:Very Large Array at D-configuration
The primary beam size of VLA at 1.5GHz at D-configuration is around 30arcmint;
26 working antennas, effective bandwidth of 43 MHz, an rms of 0.02mJy/beam of 6hrs on-source time, the peak-to-rms is tended to be greater than 10.
Moreover, the angular distribution of the flux could be resolved (right panel)

26. Synchrotron radio emission from nearby dIrrs:
B_dIrr > B_dSph
Stronger radio flux_DM from dIrrs
Contaminated by
Radio: Cosmic Ray e- accelerated by
SNe from massive star
Tight and universal FIR-radio
correlation in normal galaxies
Star formation rate
Golbular clusters vs. dwarfs galaxies. No need for dark matter (probably) in globulars because there is enough stellar mass.
Dwarfs are more extended and require DM within the tidal radial.
-Interesting ‘in between’ population. These could be tidally disrupting dwarfs or globulars.
-SDSS only covers 20% of the sky. Does this mean there are 5x more satellites?
FIR: UV radiation from young star
re-emitted in the surrounding dust

27. Possible explanation for such a trend is that either the FIR are overestimated in low luminosity galaxies or another kind of non-thermal contribution should be considered.
Require to be update

28. Current Work Larger Samples Good SFR Indicator FIR IR_tot Halpha UV ?
Nearby dIrrs with
Vmax-Rmax
Arxive：

29. Summary Be cautious to interpret experiment data
*multi-wavelength consistence
*other dark halos
Electrons&positrons produced by DM annihilating as an universal source in dark halos with different scales;
Clusters and dwarf galaxies are both potential to be good systems for indirect detection of DM
Multi-wavelength consistence are needed
Lower frequency observations in dwarf galaxies are generally required

30. Thank You