Gamma-rays from Dark Matter Annihilation in Milky Way Satellites Louie Strigari UC Irvine, Center for Cosmology Getting Prepared for GLAST UCLA, Collaborators: James Bullock, Manoj Kaplinghat (UC Irvine), Savvas Koushiappas (LANL)

Dark Matter in the Milky Way

Dark Matter Annihilation Flux = Particle Physics x Astrophysics Louie Strigari, UC Irvine GLAST, UCLA Relic abundance set by annihilation cross section

Dark Matter Annihilation Sites  Galactic center: astrophysical uncertainties, backgrounds [e.g. Bergstrom, Ullio, Buckley 1999; Hooper & Dingus 2004; Profumo 2005]  Dark substructures: [Calcaneo-Roldan & Moore 2000, Tasitsiomi & Olinto 2002; Stoehr et al. 2003; Koushiappas, Zentner, & Walker 2003; Pieri, Branchini, Hofmann 2005, Koushiappas 2006; Baltz, Taylor, Wai 2006, Diemand, Kuhlen, Madau 2006]  Luminous satellites: [Baltz et al. 2000; Tyler 2002; Evans, Ferrer, Sarkar 2003, Bergstrom & Hooper 2005, Pieri & Branchini 2004, Profumo & Kamionkowski 2006, Colafrancesco, Profumo, Ullio 2006, Strigari, Koushiappas, Kaplinghat, Bullock 2007] Louie Strigari, UC Irvine GLAST, UCLA

Orders of magnitude more dark matter substructures in numerical simulations than observed Milky Way Satellites: The ``Missing Satellites Problem’’ Possible that up to 3x more exist at these luminosities [e.g. willman et al 2004] Census of Milky Way Satellites (Circa 2003) Name Year Discovered LMC1519 SMC1519 Sculptor 1937 Fornax 1938 Leo II1950 Leo I1950 Ursa Minor 1954 Draco 1954 Carina 1977 Sextans 1990 Sagittarius 1994 Louie Strigari, UC Irvine GLAST, UCLA

Walker et al ApJ 2006 Kinematics of Milky Way Satellites Satellites are modeled with the jeans equation: Louie Strigari, UC Irvine GLAST, UCLA

Klypin, Kravtsov, Bullock, Primack 01 Highest resolution simulations indicate that the inner slope is in the range [Navarro et al. 2004, Diemand et al. 2005] Scale as 1/r in the central regions. ‘ NFW ’ profile break radius outer radius Density Profiles of CDM Halos Louie Strigari, UC Irvine GLAST, UCLA

Strigari et al. ApJ 2006 Fornax Line-of-sight velocity dispersion All dsphs fit by both cores and cusps, but focus on cusps for CDM Louie Strigari, UC Irvine GLAST, UCLA

Parameter Degeneracies Louie Strigari, UC Irvine GLAST, UCLA Strigari, Koushiappas, Bullock, Kaplinghat PRD 2007

Masses of the luminous satellites Strigari, Bullock, Kaplinghat, Diemand, Kuhlen, Madau 2007 Best-constrained parameter is the mass within about 600 pc. Louie Strigari, UC Irvine GLAST, UCLA

Constraints on Astrophysical Parameters Louie Strigari, UC Irvine GLAST, UCLA Strigari, Koushiappas, Bullock, Kaplinghat PRD 2007

Two order of magnitude boost? Fluxes are ‘boosted’ with substructure LS, Koushiappas, Bullock, Kaplinghat PRD 2007 Boost factor Louie Strigari, UC Irvine GLAST, UCLA

How will we know that we’ve detected dark matter? Consider the ratio of fluxes from different dSphs 1)Fluxes must fall within the region determined by the CDM prior 2)Flux ratio is less sensitive to astrophysical processes Louie Strigari, UC Irvine GLAST, UCLA

Census of Milky Way Satellites (Circa 2007) Name Year Discovered LMC1519 SMC1519 Sculptor 1937 Fornax 1938 Leo II1950 Leo I1950 Ursa Minor 1954 Draco 1954 Carina 1977 Sextans 1990 Sagittarius 1994 Canis Major 2003 Ursa Major I2005 Willman I 2005 Ursa Major II2006 Bootes2006 Canes Venatici I2006 Canes Venatici II2006 Coma 2006 Leo IV2006 Hercules 2006 Leo T 2007 Louie Strigari, UC IrvineKICP, Belukurov et al 2006

New data sets strongly constrain mass and gamma- rays fluxes from luminous satellites How massive are the new, low-luminosity dwarfs? Will these be promising targets? Stay tuned….. Concluding remarks Louie Strigari, UC Irvine GLAST, UCLA