The Gamma-Neutrino Connection in Transparent Sources – the Observational Side Alexander Kappes University Wisconsin-Madison Workshop on Non-Thermal Hadronic Processes in Galactic Sources 14. – 16. January 2008, Heidelberg, Germany

Alexander Kappes, UW-MadisonHeidelberg Germany, 14. January Overview Transparent sources and flux calculations General remarks concerning signal and background event rates in neutrino telescopes Discussion of event rate predictions in neutrino telescopes for selected sources Generic significance estimate

Alexander Kappes, UW-MadisonHeidelberg Germany, 14. January Transparent Sources Transparent sources ⇒ TeV g transparent sources Source classes: SNRs, PWNe, diffuse emissions, g sources with no counterpart Allows to make solid prediction for maximal expected neutrino flux from measured g-ray flux Strongest TeV g-ray sources (~ 1 crab): Northern hemisphere: RX J1713.7–3946 (SNR) RX J0852.0–4622 (SNR) Vela X (PWN) Southern hemisphere: MGRO J (Cygnus, ambiguous) Crab (PWN) Kappes et al., 2007 (derived from Kelner et al. 2006)

Alexander Kappes, UW-MadisonHeidelberg Germany, 14. January Skymap of TeV g-ray Sources

Alexander Kappes, UW-MadisonHeidelberg Germany, 14. January Neutrino Telescope Parameters Source identification requires good pointing resolution ⇒ muons from CC interactions only suitable channel First generation neutrino telescopes (AMANDA, ANTARES): Instrumented volume: ~ 0.01 km 3 n m effective area: ~ 0.01 m 1 TeV, ~ 3 m 100 TeV n m angular resolution: 0.3 o – 2.0 o n m energy resolution: ~ factor 2–3 (CC muon neutrinos) Next generation neutrino telescope (IceCube, KM3NeT?): Instrumented volume: ~ 1 km 3 n m effective area: ~ 0.2 m 1 TeV, ~ 60 m 100 TeV n m angular resolution: 0.1 o – 1.0 o n m energy resolution: ~ factor 2–3 (CC muon neutrinos)

Alexander Kappes, UW-MadisonHeidelberg Germany, 14. January Neutrino Telescope Parameters cont'd Neutrino effective area rises strongly with energy cross section increases light output increases n m : muon range grows; 14 PeV ! IceCube (80 Strings) n m effective area

Alexander Kappes, UW-MadisonHeidelberg Germany, 14. January Signal and Background Rates Sensitive to sources in opposite hemisphere ⇒ requires detectors in both Hemispheres Rate of mis-reconstructed muons must be low ⇒ quality cuts reduce effective area (signal rate) significantly Quality cuts to reach good pointing resolution ⇒ further reduction of effective area southern hemisphere northern hemisphere Event rates: atmospheric muons (1° x 1°)(~10 -2 Hz) atmospheric neutrinos (1° x 1°) (~10 -7 Hz) Generic flux ( E -2 (TeV cm 2 s) -1 ) (~10 -7 Hz) Example: IceCube 22 strings (trigger level)

Alexander Kappes, UW-MadisonHeidelberg Germany, 14. January Signal and Background Rates cont'd Atm. n background about same as source flux ⇒ source size very important ⇒ better pointing resolution reduces background Size of search window often underestimated 1 s window (Gaussian dist.)  less than 50% of signal retained ! Optimal choice ~1.6 s  factor 2 increase in background (~70% of signal retained) Lower energy cuts to improve Signal/Bckg ratio: Energy resolution (Factor ~ 3) ⇒ migrations True vs. rec. E: Signal (E -2 ): +5%, Bckg (E -3.7 ): +50% southern hemisphere northern hemisphere IceCube

Alexander Kappes, UW-MadisonHeidelberg Germany, 14. January RX J1713.7–3946 (SNR) One of brightest TeV g-ray sources in southern hemisphere (  = 1.3 o ) S/B improvement probably possible by selecting high flux region RX J (HESS) 1.3 o

Alexander Kappes, UW-MadisonHeidelberg Germany, 14. January History of neutrino rate predictions Unfortunately, constant decrease in expected event rates (n oscillation, wrong g-ray measurements, cut-offs not taken into account) Now expecting: E n > 1 TeV: 1–3 (atm. n = ~3) evt yr -1 E n > 5 TeV: ~0.4 (atm. n = ~0.8) evt yr -1 ⇒ Not detectable for 1 st generation telescopes Distefano 2006 Kistler & Beacom 2006 Kappes et al (1 km 3 inst. vol.) RX J (HESS) Alvarez-Muniz & Halzen 2002 Costantini & Vissani 2005 Distefano 2006 Kistler & Beacom 2006 Kappes et al. 2007

Alexander Kappes, UW-MadisonHeidelberg Germany, 14. January Impact of High Energy Cut-Offs Effective area increases rapidly with energy ⇒ high energy cut-offs have large impact on event rate E n > 1 TeV: with: 0.9 evt yr -1 without: 1.7 evt yr -1 (+90%) Integrated events for 1 year KM3NeT Most recent effective area with full event reconstruction (not optimized) A. Kappes et al., arXiv: details in: Kuch 2007, ​ / erlangen.de/publications RX J (HESS)

Alexander Kappes, UW-MadisonHeidelberg Germany, 14. January RX J0852.0–4622 (Vela Junior, SNR) TeV g flux comparable to RX J1713 but larger source diameter (southern hemisph.) RX J0852.0–4622 (HESS) 2.0 o Kistler & Beacom 2006 Kappes et al Event rates: E n > 1 TeV: 1–5 (atm. n = ~ 8) evt yr -1 E n > 5 TeV: ~ 0.5 (atm. n = ~ 2) evt yr -1 Integrated events for 1 year KM3NeT new eff. area

Alexander Kappes, UW-MadisonHeidelberg Germany, 14. January proton index: 2.2 Cygnus (MGRO J , ambiguous) Source in southern hemisphere with up to ~ 1 crab TeV g flux (  = 0.6 o ) (Halzen & ´O Murchadha 2007) Cygnus region (MILAGRO) proton index: 2.34 (Halzen & ´O Murchadha arXiv: ) EGRET measurements upper bound

Alexander Kappes, UW-MadisonHeidelberg Germany, 14. January Cygnus (MGRO J , ambiguous) cont'd Diff. source evts: g n flux calc. (-35%), finite window (-28%) ⇒ factor ~ 2 Details crucial for detectability window: 3 deg 2 (r = 1.0 o ) E > 1 TeV: source= ~ 1.5 evt yr -1 backgr = ~ 2 evt yr -1 Beacom & Kistler 2007 Phys.Rev.D75: window: 3.7 deg 2 (r = 1.1 o ) E > 1 TeV: source= ~ 0.7 evt yr -1 backgr = ~ 2.8 evt yr -1 Halzen &´O Murchadha arXiv: window: 1 deg 2 (r = 0.6 o ) E > 1 TeV: source= ~ 1.5 evt yr -1 backgr = ~ 0.4 evt yr -1 Integrated events for 1 year IceCube ( proton index = 2.34)

Alexander Kappes, UW-MadisonHeidelberg Germany, 14. January MGRO J / HESS J Event rates: E n > 20 TeV: ~1 (atm. n = ~ 0.3) evt yr -1 Integrated events for 1 year IceCube

Alexander Kappes, UW-MadisonHeidelberg Germany, 14. January and what about the Crab (PWN)? Pulsar Wind Nebulae generally expected to accelerate electrons... but maybe significant fraction of nuclei in pulsar wind !? Positive: point source for n telescopes (< 0.1 o ) pointing resolution determines background Source in lower southern hemisphere ⇒ longer visible for IceCube Rates per year E > 1 TeV in IceCube: Source: 1–3 Backgr: ~ 3 Kistler & Beacom 2006 A. Kappes IceCube

Alexander Kappes, UW-MadisonHeidelberg Germany, 14. January Integrated events for 1 year KM3NeT new eff. area Vela X (PWN) Bright TeV g-ray source in southern hemisphere Kistler & Beacom 2006 Kappes et al Event rates: E n > 1 TeV: 1.5–5 (atm. n = ~ 2) evt yr -1 E n > 5 TeV: ~ 1 (atm. n = ~ 0.5) evt yr -1 Vela X (H.E.S.S.) ~1 o

Alexander Kappes, UW-MadisonHeidelberg Germany, 14. January Summary Expected Event Rates (per year) E > 1 TeV E > 5 TeV northern hemisphere Type Ø [ o ] Src Bkg Src Bkg RX J1713.7–3946 SNR 1.3 1–3 ~3 ~ 0.4 ~ 0.8 RX J0852.0–4622SNR 2.0 1–5 ~ 8 ~ 0.5 ~ 2 VELA XPWN –5 ~ 2 ~ 1 ~ 0.5 HESS J1825–137PWN –0.7 ~ 0.7 ~0.4 ~0.2 Galactic CentreUMBI <0.1 ~0.2 ~ 0.5 ~0.1 ~0.1 southern hemisphere MGRO J UMBI – – –1 0.1–1 Crab NebulaPWN <0.1 1–3 ~ 3 ~ 0.7 ~ 1.2 MGRO J UMBI 0.2 E > 20 TeV: ~ 1 ~ 0.3 GemingaPWN 2.8 ~ 2 ~ 20 Cas ASNR <0.1 ~ 0.1~ 1.5 Regions of diffuse emission difficult, e.g. Galactic Centre Ridge (large size)

Alexander Kappes, UW-MadisonHeidelberg Germany, 14. January Significance Depends on many analysis details (binned  unbinned method, use of energy information etc.) Simple estimate: n obs incompatible with Null hypothesis (Assumption: mean bkg n bkg known with high precision) Individual sources might be difficult Source stacking may help e.g. Vela X + HESS J1825: E n > 5 TeV: ~ 1.5 (atm. n = ~ 0.7) evt yr -1

Alexander Kappes, UW-MadisonHeidelberg Germany, 14. January Summary g-ray transparent sources allow to make solid predictions for (maximal) expected neutrino flux Recent calculations yield consistent picture 1 st generation telescopes (AMANDA, ANTARES) probably not able to detect Galactic TeV g-ray transparent sources Individual sources remain challenging to detect even for 1 km 3 detectors (a few signal events per year expected but background rate of same size as signal rate) Analysis details (e.g. window size, energy resolution) crucial for detectability