The Pierre Auger Observatory: Recent Results and Future Plans

Transkript

1 AERA Auger Engineering Radio Array The Pierre Auger Observatory: Recent Results and Future Plans John Kelley for the Pierre Auger Collaboration Radboud University Nijmegen The Netherlands Beyond 2010, Cape Town February 4, 2010

2 Cosmic Ray Spectrum Charged particles with steep power law spectrum Low flux at high energy: detect via extensive air showers Opportunities for new physics: cosmic ray sources cosmic ray composition UHE particle interactions / propagation E 2 dn/de (GeV cm -2 sr -1 s -1 ) protons only electrons positrons antiprotons all-particle knee 1 m -2 yr -1 CAPRICE BESS98 AMS Ryan et al. Grigorov JACEE Akeno Tien Shan MSU KASCADE CASA-BLANCA DICE HEGRA CasaMia Tibet AGASA HiRes LHC E kin (GeV / particle) ankle 1 km -2 yr -1 Figure 1. Global view of the cosmic-ray spectrum. Gaisser J. Kelley, Beyond2010 2

3 Ultra-High Energy Cosmic Rays (UHECR) Highest energy particles known in the Universe Composition unknown Sources + acceleration mechanism unknown Astrophysical acceleration or decay of exotic particles? More later UHECR spectra (2004) Cutoff in spectrum or not? Expected from interactions with CMB (GZK effect) J. Kelley, Beyond2010 3

4 Pierre Auger Observatory Hybrid air shower detector Auger South Southern site (3000 km2) in Argentina completed 2008 Northern site (21000 km2) planned for Colorado, U.S.A J. Kelley, Beyond2010 4

5 Hybrid Detection fluorescence track fluorescence track Cherenkov tank signals Hybrid observation: energy cross-calibration (~20%), better angular resolution (~0.5 ) but FD duty cycle is ~10% J. Kelley, Beyond2010 5

6 Latest Results: UHECR Energy Spectrum lg(e/ev) ) J / (A! E HiRes I HiRes II Auger 2008: Continuation of power law rejected at 6σ (confirms HiRes) Suppression energy consistent with GZK onset ] 2 ev -2 yr -1 sr -1 J(E) [km Energy [ev] ! sys (E)=22% 2009: combined FD + SD spectrum protons with strong source evolution? iron with another component below ankle? 3 E Auger combined Fit Proton, "=2.6, m=0 Proton, "=2.3, m=5 Iron, "=2.4, m=0 Difficult to rule out non- GZK causes source cutoff? Lorentz violation? see e.g. Scully & Stecker Energy [ev] Schüssler et al J. Kelley, Beyond2010 6

7 Latest Results: Anisotropy Hague et al (ICRC) Release pending 2007: 27 events above 55 EeV (ovals); correlation with nearby AGN (red crosses) 2009: 58 events above 55 EeV: correlation with original AGN catalog weakens A posteriori investigations of: Centaurus A region correlations with other catalog(s) e.g. SWIFT-BAT Isotropy rejected at 99% CL J. Kelley, Beyond2010 7

8 Composition Slant depth X max (integrated density) of shower maximum in atmosphere energy and composition-dependent higher in atmosphere for heavier nuclei (interact, lose energy sooner) Shower-to-shower fluctuations of X max iron showers (~superposition of many single-nucleon showers) have fewer fluctuations X max J. Kelley, Beyond2010 8

9 Latest Results: Composition Bellido et al (ICRC) Abraham et al., accepted PRL (2010) Both indicate composition getting heavier or protons behaving differently than expected? (see e.g. Ulrich et al., arxiv: ) J. Kelley, Beyond2010 9

10 Neutrino Detection via Air Showers *+,"+-"./(+%,0&#&"! "#$%&'!()&*+%, X max! 700 g cm "2 normal inclined shower: only muons left "#$%$&!'#$()* + X! max! 950 g cm "2!"#$%&'(#)*++,'+-#. neutrino-induced shower: young EM component (broad signals in tanks)!"1/04&51#6&%&708#6&&8#,'#*(9018/&5&#:;< tau decay from Earth-skimming ν τ : dense target, but only one flavor J. Kelley, Beyond

11 Limits on Diffuse Neutrino Flux 89-&*&#05:- COSMOGENIC!s J. Kelley, Beyond

12 Photon Fraction Limits UHE photons predicted in many top-down models super-heavy dark matter topological defects Z-bursts Photon-induced showers: develop deeper in atmosphere SD: measure shower front curvature, thickness FD: measure longitudinal profile directly Abraham et al Data consistent with only hadrons top-down models disfavored GZK photon flux may be eventually accessible J. Kelley, Beyond

13 Enhancements at Auger South HEAT: High Elevation Auger Telescopes AMIGA: Auger Muon and Infill Ground Array AERA: Auger Engineering Radio Array J. Kelley, Beyond

14 Auger Engineering Radio Array AERA: Auger Engineering Radio Array Detect air showers via radio pulses (e+e- in geomagnetic field) 20 km2 extension to southern site: 150 stations voltage [mv] found to be within a factor of two or better. Presently, the predictions for the radio-detector array are at this level of precision. Further cross checks on the predicted results have been made by other means of parameterizations using, e.g., world data on radio measurements. pole 1 EW 80 NS While we are using RDAS for answering the design questions of the proposed radio detector 60 array, a task force is integrating the radio software into the Auger Offline framework (see section 40 7). With this effort it will be possible to simulate and reconstruct all three detector systems, 20 surface detector, fluorescence detector, and radio detector, within one framework, allowing for 0 cross checks and combination of complementary shower information Site layout time [µ s] sample 2 10 ev event 18 The situation It is proposed to set up the radio antenna array at the site of the AMIGA array. is outlined in Fig. 11. For reference, tank names of the surface array are indicated. The large hexagon indicates the position of the AMIGA infill array (water-cherenkov detectors) and the smaller hexagon represents a possible infill to the infill array. These arrays are located in the field of view of the HEAT fluorescence telescopes (the latter are just outside the left border of Fig. 11). In the map the position of the CRS, an abandoned train station, a high voltage power line, and a fence are indicated. The Site e Duty cycle: ~100%; ~5000 events/year Start deployment this year! r lin owe p train station CRS HEAT fence Figure 11: Layout of the proposed antenna field. ~20 km J. Kelley, Beyond2010 antennas ~150 Baseline parameters for the antenna array are about 150 antennas distributed over an area of approximately 20 km. It is with assumed that the construction will be divided into three stages, operation together infill/heat/amiga starting with about 22 antennas in a prototype cluster, followed by further 52 antennas, and three85 antenna spacings to cover efficiently 17.2 < lg E < 19.0 finally antennas. In the map, the locations of the antennas are marked as red boxes. Boxes threeborder deployment (22borders + 52 to + stage 85 antennas) correspond tostages stage 1, black 2, and white borders to stage 3. without

15 Summary Pierre Auger UHECR results: suppression in spectrum observed suggestive anisotropy results need more statistics neutrino and photon limits: no hints beyond SM yet composition getting heavier? Strategy for further research: more data from Auger South searches for exotics: Q-balls, magnetic monopoles, etc. 7x larger array: Auger North expand complementary detection techniques like radio J. Kelley, Beyond

16 Thank you! Czech Republic France Germany Italy Netherlands Poland Portugal Slovenia Spain United Kingdom Argentina Australia Brazil Bolivia* Mexico USA Vietnam* *Associate Countries Radio Working Group J. Kelley, Beyond

17 GZK Suppression 10 5 Suppression expected above 50 EeV due to interaction with CMB photons (Greisen-Zatsepin-Kuzmin) If spectrum keeps going Sources unexpectedly close? New physics (e.g. violation of Lorentz invariance)? Situation 4-5 years ago totally unclear loss length Mpc e + e - photopion E ev Berezinsky et al J. Kelley, Beyond

18 Air Shower Detection Water (or ice) Cherenkov tanks detect EM shower front on ground near-100% duty cycle Fluorescence telescopes follow Nitrogen fluorescence as shower develops good for calorimetry, measurement of shower maximum (particle ID) duty cycle is ~10% J. Kelley, Beyond

19 The Neutrino Connection Trans-GZK protons lose energy via CMB photopion production GZK neutrino flux Also produces UHE neutrinos! Nuclei will tend to photodisintegrate first (reduced flux) Measurement of GZK neutrino flux: source spectrum source evolution composition range of iron best-fit proton Anchordoqui et al J. Kelley, Beyond

20 Radio Emission from Air Showers Separation, acceleration of e +, e - in geomagnetic field secondary: charge excess, moving dipole Broadband radio pulse (width ~50 ns) Emission is coherent up to 100 MHz RF power scales as (E primary ) 2 Observed by LOPES, CODALEMA, MAXIMA detectors geomagnetic asymmetry verified larger experiment needed to verify details of emission e + e + Shower front e + e + Shower axis e + e + e + e! e! e! B e! e! e! e! J J. Kelley, Beyond

21 Geomagnetic Origin Simplification: geomagnetic origin implies Asymmetry confirmed with LOPES, CODALEMA experiments Ardouin et al J. Kelley, Beyond

22 Composition Primary composition by: lateral distribution reconstruction of shower front curvature Simulations only at this point: need larger array, more events! 32 to 64 MHz filtered amplitude [µv m -1 ] ! = 60, ev gamma proton iron SNR of 10 for urban noise SNR of 10 for rural noise SNR of 10 for ideal noise distance from shower centre [m] Huege et al J. Kelley, Beyond

23 Expected Event Rates Effective area [km 2 ] LOPES extr. CODALEMA extr. MC simul Events per year LOPES extr. CODALEMA extr. MC simul Energy lg E [ev] Energy lg E [ev] ~5000 events / year with E > 3 x ev ~800 events / year with E > 1 x ev J. Kelley, Beyond

24 AERA Physics Radio will open a new window onto cosmic ray physics! J. Kelley, Beyond