1. CLUES on Fermi-LAT: prospects for μνSSM gravitino dark matter extragalactic detection
Germán Gómez Vargas
Universidad Autónoma de Madrid
Instituto de Física Teórica UAM/CSIC
INFN Roma Tor Vergata
In collaboration with: A.J.Cuesta, M. Fornasa, F.Prada, C.Muñoz, G.Yepes, and F. Zandanel.

2. Overview Evidences of DM Gamma-ray lines from μνSSM gravitino DM
Dark matter on Fermi-LAT data
μνSSM gravitino DM detection prospects for Fermi-LAT
Conclusions and outlook

3. DM evidences
Evidences indicating the presence of DM can be obtained at very different scales: from cosmological ones through CMB, down to galactic scales considering rotation curves.

4. DM evidences
The excess of matter is knows to have some special properties:
Be NOT-BARYONIC
Be COLD
Have a neutral electric and color charge
Interact only via gravitational force.
Be massive
NO standard model (SM) particle has these properties, then we have to look in theories beyond the SM as Supersymmetry.

5. Gamma-ray lines from Gamma-ray lines from μνSSM gravitino DM gravitino DM
The μνSSM “ μ from ν Supersymmetric standard model” (Lopez-Fogliany & Munoz 2006) is a model that has been proposed to solve the μ problem of the MSSM by means of the neutrinos' right-handed super-fields νH1H2
In the μνSSM R-parity is broken allowing the LSP to decay. Then gravitino is a natural DM candidate since its lifetime ~ 1027s becomes much longer than the age of the Universe ~ 1017s.

6. Gamma-ray lines from μνSSM gravitino DM gravitino DM
The gravitino decays through the interaction gravitino- photon-photino due to the photino-neutrino mixing after sneutrinos develop their VEVs opening the following channel:
where |Uγν| determines the photino content of the neutrino, and is constrained to be |Uγν|2~ s – s in order to reproduce neutrino masses, and m3/2 of the order of few GeV → Possible Fermi-LAT detection.
Note just one photon and one neutrino are produced → The signal is a line at E=m3/2/2!

7. Dark matter on Fermi-LAT data
The Fermi Gamma-Ray Telescope performs gamma- ray measurements over the whole celestial sphere.
Its main scientific instrument is the Large Area Telescope (LAT)
Energy range ~50 MeV – 300 GeV, resolution 7%<σE<15%
Angular resolution ~ 0.1 deg

8. Dark matter on Fermi-LAT data
Although in the halo of the Milky Way the DM flux is maximized in the direction of the galactic center where the DM density is larger, the background is not fully understood.
In structures like galaxy clusters DM is the main component. Those kind of objects in our local Universe are promising targets for DM searches.
We explore the prospects for detecting gravitino DM in near extragalactic objects like clusters of galaxies on 5 years Fermi-LAT simulated data.

9. Dark matter on Fermi-LAT data
The simulation of gamma-ray events was carried out with the gtobssim routine, part of the Fermi Science Tools package v9r16p1.
Its output is a map of mock gamma-rays counts with corresponding spacial direction, arrival time and energy distributed according to an input flux model
Fermi tools are public available on NASA page as well as the background diffuse emission, both galactic and isotropic extragalactic that we use for this work.

10. The DM signal comes from: 
Cuesta et al. 2011
DM smooth halo compatible with rotation curves for the MW halo as modeled in Tavio et.al
Isotropic DM extragalactic emission at z > 0
CLUES (Constrained Local UniversE Simulations). N-body simulations aim at describing the formation and evolution of DM halos in a way to reproduce our local universe. The characteristics if the most massive clusters as Virgo, Coma and Perseus, together with the Geat Attractor, are well reproduced.

11. The DM signal comes from:
The μνSSM  
Cuesta et al. 2011
DM smooth halo compatible with rotation curves for the MW halo as modeled in Tavio et.al
Isotropic DM extragalactic emission at z > 0
CLUES (Constrained Local UniversE Simulations). N-body simulations aim at describing the formation and evolution of DM halos in a way to reproduce our local universe. The characteristics if the most massive clusters as Virgo, Coma and Perseus, together with the Geat Attractor, are well reproduced.

12. Dark matter on Fermi-LAT data
The ability of Fermi-LAT to detect lines depend on the energy resolution. It is not include on the standard Fermi tools because it does not affect too much the results of many astrophysical analysis.
We include the energy resolution using a Gaussian function to convolve the gravitino DM line in order to obtain the flux.

13. μνSSM gravitino DM prospects of detection with Fermi-LAT
S/N all-sky map. DM events come from gravitino decay. This Gravitino
m3/2 = 8GeV t3/2 = 5x1027 s is consistent with the constrains found
in Choi et. al. JCAP 03(2010) 028.

14. μνSSM gravitino DM detection prospects for Fermi-LAT
We select Virgo cluster as the best target to obtain our predictions. It is far from galactic plane and M87 is the only one detected point source near Virgo.
With the purpose of scanning the most interesting portion of the μνSSM parameter space, we re- simulate the gamma-ray events for the region of 5x5 deg around Virgo. We run 17 simulations of this region, each one with a different value for m3/2 from 0.6 to 14 GeV.

15. μνSSM gravitino DM detection prospects for Fermi-LAT
Constraints on the lifetime versus mass for gravitino DM in the μνSSM.
Fermi-LAT team searches for lines 7 GeV, i.e. m3/2>14 GeV

16. Conclusions and outlook
We have found that a gravitino with a mass range of about GeV, and a lifetime of 5x10 27 s (1028) would be detectable by the Fermi-LAT with a S/N of 5σ (3σ) in 5 years of operation.
We have confirmed the potential of using extragalactic massive structures as optimal targets for decaying DM detection.
Our results can be considered as an additional motivation to extend the Fermi-LAT analysis on lines to energies below about 5 GeV

17. Backup slides
Background model.