Cosmology with Ground-Based Cherenkov TelescopesWei Cui (Purdue University)

OutlineIndirect Dark Matter SearchSignatures of annihilation of DM particles in astronomical settingsObserving planExtragalactic Background LightAbsorption of gamma rays from bright distant sources

Dark Matter Search TriangleThree complementary approachesProduce neutralino in laboratoryDirectly detect DM WIMP in specialty detectors in (underground) labsIndirect detection of astrophysical gamma rays from DM annihilation

The Sky at Different Wavelengths

TeV SourcesBlazar:14FR I:1PWN:6SNR:5MG:2Be Bin.:1Unid.:15Cui 2006

Gamma-Ray Signals

Annihilation Line?

Very Energetic Radiation Imaging Telescope Array System (VERITAS)85 m109 m85 m35 mT1T4T2T3

Recent Development Galactic CenterHESS observations of galactic center (HESS J1745-290) from 2003/4 find bulk of emission must have non-dark-matter origin (Aharonian et al.,Phys. Rev. Lett. 97, 221102 (2006).Spectrum appears to have simple power law dependence in contrast to expectation for gamma rays produced by neutralino annihilationGalactic Center may be difficult place to search for Dark MatterAharonian et al. PRL 97,221102 (2006)

Potential TargetsDwarf Galaxies large mass to light ratioGlobular Clusters dense core gives rise to DM cusp?Galaxy ClustersDM dominatedknown density profilePossible DM cusp in cluster centerNearby Galactic Nuclei possible cuspy DM near center

Results with Whipple

Observing Plan with VERITAS @ BasecampObservations 2006M15(GC): 10 hours, September, B weather, 2 telescopes

Targets 2007 Survey several sources Spring, 2007Ursa Minor(DG) 24 hours*Draco(DG) 21 hours*M87(RG) 50 hours* ; comes for free as part of non-blazar proposalFall, 2007M15(GC) allocation to be determined; hoping for 30 hrs. in Oct

Targets 2008 Plan also will be guided by GLAST results! Sextans(DG) Jan, 2008?M13(GC) Apr, 2008?Coma (CL)?Follow up on minihaloes should GLAST be fortunate enough to find evidence early onGC Globular Cluster, DG Dwarf Galaxy, CL Galaxy Cluster, RG radio galaxy* Primary Target

Cosmic BackgroundRadioUse TeV beams from, e.g., blazars, to probe the IR background

Tentative EvidenceKrennrich et al. 2001

Universe more transparent to TeV gamma rays?lower limitsfrom galaxycountsmeasure-ments upperlimitsXXHoffman 2005

Intrinsic vs Extrinsic Mrk 421Blazejowski et al. 2004Courtesy of Alex Konopelko

Blazar Key Science Project115 hrs/Year Total, Three Components:40 hrs/year: Multiwavelength Campaign for >2 Crab Flares Sample Temporal Evolution of Flux and Spectra.40 hrs/year: Intensive Observations of 4 Sources in 2 Years Object RA(J2000) Dec(J2000) z Class1ES 1218+304 12 21 21.9 +30 10 37 0.182 HBL1ES 2344+514 23 47 04.8 +51 42 18 0.044 HBLBL 1101-232 11 03 37.6 -23 29 30 0.186 HBLH 1426+428 14 28 32.7 +42 40 20 0.129 HBL[1ES 1959+650] 19 59 59.9 +65 08 55 0.048 HBL(c) 35 hrs/year: Explore Other Blazar Classes Object RA(J2000) Dec(J2000) z Class 1ES 0120+340 01 23 08.9 +34 20 50 0.272 HBL1ES 0806+524 08 09 49.2 +52 18 58 0.138 HBLBL Lacertae 22 02 43.3 +42 16 40 0.069 IBLB2 0321+33 03 24 41.2 +34 10 45 0.062 HSFRQ1ES 1627+40.2 16 29 01.3 +40 08 00 0.271 HSFRQ1ES 0033+595 00 35 52.6 +59 50 05 0.086 HBL BL 0647+250 06 50 46.6 +25 03 00 0.203 HBLW Comae 12 21 31.7 +28 13 58 0.102 IBL3C 66A 02 22 39.6 +43 02 07 0.444? IBLMrk 1218 08 38 11.0 +24 53 43 0.028 HSFRQ WGA J0838+2453.

Smithsonian Astrophysical Observatory * Adler Planetarium Purdue University * Barnard College, NY Iowa State University * DePauw University, IN Washington University, St. Louis * Grinnell College, IA University of Chicago * University of California, Santa Cruz University of Utah * University of Massachussetts University of California, Los Angeles * Cork Institute of Technology McGill University, Montreal * Galway-Mayo Institute of Technology National University of Ireland, Dublin * National University of Ireland, Galway University of Leeds * Argonne National LabAssociate Members Project office: Whipple observatory SAO VERITAS Collaboration ~65 members in more than 20 institutionsFunding from NSF/DOE/Smithsonian/PPARC/SFI/NSERC