Diffuse axion-like particle searches

Transcription

1 ECT* EUROPEAN CENTRE FOR THEORETICAL STUDIES IN NUCLEAR PHYSICS AND RELATED AREAS TRENTO, ITALY Institutional Member of the European Expert Committee NUPECC Diffuse axion-like particle searches Castello di Trento ( Trint ), watercolor 19.8 x 27.7, painted by A. Dürer on his way back from Venice (1495). British Museum, Axions at the crossroads: QCD, dark matter, astrophysics Trento, November 20-24, 2017 Main Topics -Theoretical motivations for axions: Recent developments -Impact of QCD on dark matter axion predictions -Experimental axion searches: status and perspectives -Astrophysical bounds and hints for axions Keynote participants Evan Berkowitz (Fz Jülich, Germany), Michele Cicoli (Bologna Univ., Italy), Sacha Davidson (IN2P3, CNRS, France), Inma Domínguez (Granada Univ. Spain, Germany), Horst Fischer (ALU-Freiburg, Germany), Zoltan Fodor (Wuppertal University, Germany), Claudio Gatti (LNF-INFN, Italy), Maurizio Giannotti (Barry Univ., USA ), Carlo Ligi (LNF-INFN, Italy), Axel Lindner (DESY Hamburg, Germany), Daniele Montanino (Lecce Univ., Italy), Antonello Polosa (Rome University, Italy), Javier Redondo (Zaragoza Univ., Spain), Andreas Ringwald (DESY, Hamburg, Germany), Marco Roncadelli (INFN Pavia, Italy), Gray Rybka (University of Washington, USA), Sayantan Sharma (BNL, USA ), Günter Sigl (Hamburg Univ., Germany), Frank Steffen (MPI Munich, Germany), Oscar Straniero (Teramo Observatory, Italy), Giovanni Villadoro (ICTP, Trieste, Italy), Arne Wickenbrock (Johannes Gutenberg University Mainz, Germany) PRISMA Cluster of Excellence and Mainz Institute for Theoretical Physics Johannes Gutenberg-Universität Mainz Organisers Mariapaola Lombardo (LNF, INFN, Italy), Alessandro Mirizzi (Bari Univ. & INFN Bari, Italy) Director of the ECT*: Pr ofessor J ochen Wambach (ECT*) The ECT* is sponsored by the Fondazione Bruno Kessler in collaboration with the Assessorato alla Cultura (Provincia Autonoma di Trento), funding agencies of EU Member and Associated States and has the support of the Department of Physics of the University of Trento. For local organization please contact: Susan Dr iessen - ECT* Secretariat - Villa Tambosi - Strada delle Tabarelle Villazzano (Trento) - Italy Tel.:( ) Fax:( ) , ect@ectstar.eu or visit Thanks to my collaborators: Hendrik Vogel and Manuel Meyer

2 Contents Motivation IceCube observations Methodology Preliminary results

3 Motivation

4 Parameter space for ALPs Fermi- LAT ALP dark matter CAST Meyer Many different ways to search for ALPs in astrophysical systems Can we make progress in the unconstrained regions?

5 Motivation from IceCube: a new source of high-energy photons

6 Puzzling questions about the high energy astrophysical universe Gaisser Fermi- LAT Gamma-ray sky: what process produces them? Leptonic: Hadronic: e +! e + p + p! 0! + p + p! /K +...! / The key difference are the neutrinos Cosmic rays observed over a huge energy range Neutrinos are inevitably produced in cosmic ray interactions

7 IceCube neutrino telescope Gigaton effective volume neutrino detector at South Pole 5160 Digital Optical Modules distributed over 86 strings Completed in Dec 2010; data in full configuration from May 2011 Data acquired during construction phase is analyzed Neutrino detected through Cherenkov light emission from charged particles produced due to neutrino CC/NC interactions Credit: C Rott

8 IceCube data Diffuse and isotropic spectrum of neutrinos Time-independent Clear evidence of the astrophysical nature of these neutrinos None of them point to a specific source

9 Photons corresponding to IceCube excess p +! n + +! +... p +! p + 0! +... Kistler neutrinos IceCube excess neutrinos imply a guaranteed high energy gamma-ray background Can one use these photons to do physics? We use these photons for the first time to search for new physics Ahlers and Murase p + p!... + ±! p + p! !... +

10 Very high-energy gamma-rays exp Search for very high energy (VHE) gamma-rays (> 100 TeV) are useful in this context: CASA-MIA, KASCADE Attenuation of VHE gamma-rays important VHE CMB/EBL! e+ e Inverse Compton of the background photons by the electron positron pair produce gamma-rays with energy in the Fermi-LAT band CMB Vernetto & Lipari Esmaili & Serpcio

11 ALPs help us observe these very high-energy gamma-rays High energy astrophysical source Photon converted to ALP in the magnetic field of the source galaxy VHE photons get attenuated in space ALP propagates freely in space ON OFF search technique: in the presence of ALPs, we will observe these photons otherwise we will not observe these photons propagates freely in space Milky Way Galaxy Our technique is sensitive to a new ALP parameter space Present and near-future gamma-ray instruments like HAWC, CTA, LHAASO can detect these photons and put a new bound on the ALP parameter space ALP converted back to photon in the magnetic field of the Milky Way

12 Methodology

13 Astrophysical neutrino spectrum IceCube ICRC2017 Niederhausen etal. We use two different fits to the astrophysical " neutrino spectrum E E (E ) / Neutrino energy E b 2 + E b 2 # 1 2 Niederhausen etal. E b (TeV) Kopper etal p +! n + +! +... p +! p + 0! +... E 2 E 2 photons for 3 neutrinos Many models which reproduce the spectrum of these neutrinos IceCube ICRC2017 Kopper etal. IceCube Preliminary

14 Astrophysical parameters There are various models (~ 100+) in the literature which postulate the astrophysical sources producing the IceCube observations Astrophysical parameters (like magnetic field, photon density, plasma density) vary between them We try to follow a model-independent and conservative approach where we only take the magnetic field of the galaxy in which the neutrino source is embedded Fletcher Typical values for the total and regular equipartition magnetic field strengths for 21 galaxies We use the variations zero redshift B? =3, 5, and 10 µg at Coherence length at zero redshift = 1 kpc

15 Astrophysical parameters -2 Schober etal., B(z, )=B 0 n(z) 1/6 ( H(z)) 1/3 log(b [G]) M yr Star formation rate M yr 1 z =0 = Model for interstellar photon density in progenitor galaxies u ISRF, d = X i spectral energy density f i 8 h c 3 3 exp(h /kt i ) local magnetic field n(z, )=n 0 (1 + z) 3 particle density u [erg cm 3 Hz 1 ] log 1 d u [erg cm 3 Hz 1 ] log Schober etal., normal galaxy starburst galaxy log ( [Hz]) star formation rate,0 1/1.4 Schober etal., normal galaxy starburst galaxy log ( [Hz]) z =0 z =1 z =2 z =5 z = n [cm 3 Hz 1 ] log n [cm 3 Hz 1 ] log

16 High-energy gamma-ray production in the Milky Way The photons that we are concerned with have an energy & 20 TeV An important source of photons at these energies is cosmic-ray interaction with the interstellar medium p + p! !... + Photons at these energies have not been detected ALPs can induce spectral distortions in this gamma-ray spectrum These photons are strongly correlated with the Galactic plane Fermi-LAT Ahlers and Murase Galactic plane in 10 GeV 2 TeV

17 Gamma-ray detectors (HAWC) Gamma-rays and cosmic-rays between 100 GeV and 100 TeV DuVernois HAWC and HAWC-South: TeV all-sky gamma-ray experiments for the Northern and Southern hemispheres Angular resolution varies from ~ to 2 0 Above 10 TeV the energy resolution is below 50% Reject > 99% of cosmic-ray showers at energies above roughly 3 TeV hawc-observatory.org

18 Gamma-ray detectors (LHAASO) The Large High Altitude Air Shower Observatory (LHAASO) project All-sky instrument Detect cosmic Rays and Gamma-Rays in the wide energy range ~10 11 ev ev Uses different detection techniques: (1) LHAASO-KM2A: 1 km 2 array of 5635 scintillator detectors for electromagnetic particle detection (2) LHAASO-MD: 1 km 2 array of underground water Cherenkov tanks for muon detection (3) LHAASO-WCDA: Surface water Cherenkov detector facility ~90000 m 2 (4) LHAASO-WFCTA: 24 wide field-of-view air Cherenkov and fluorescence telescopes Sciascio The LHAASO project: a new generation cosmic-ray experiment

19 Signal morphology Vogel, Laha, and Meyer in preparation The incident ALP flux is isotropic and homogenous Due to the Galactic magnetic field, the signal on Earth is highly anisotropic: ALP bubble for Jansson & Farrar magnetic field Useful for signal v/s background discrimination

20 Preliminary results CTA LHAASO and HAWC will probe new parameter space sensitivity ADMX Haloscopes HAYSTAC ORGAN These are the farthest source of high-energy photons that we know 10 years LHAASO ALP DM Very difficult to mimic these photons by astrophysical spectrum modifications CTA Astrophysical uncertainties will decrease in the near future limit ALP DM ADMX Haloscopes HAYSTAC ORGAN New physics result with these guaranteed photon sources Promising probe Vogel, Laha, and Meyer in preparation

21 Conclusions Searching for axion like particles is one of the major frontiers of physics Many of the well motivated parameter space can be probed by astrophysical systems We show that probing the very high-energy photon flux corresponding to the IceCube neutrinos will probe new ALP parameter space This is a new search technique in ALP physics

22 Muon Tracks Caused by muons produced in CC interaction of µ / µ + Long range implies larger effective volume + Better Angular resolution ~ 1 o - Higher atmospheric neutrino backgrounds dn µ de µ tracks = N A TA det ( + E µ ) Z 1 E µ de d de CC(E )e L

23 Caused by CC interactions of and their antiparticles and NC interactions of neutrinos of all flavors Cascades e / + Calorimetric + Lower atmospheric neutrino background - Smaller effective volume - Poor angular resolution ~ 50 o dn de casc = N A TV casc CC(E ) d e, + NC (E ) d e,µ, de de

24 Neutrinos as cosmic messengers + No deflection from source + Can escape from very dense sources + No interaction on the way from source to detector + Complementary to gamma-rays... - Large detectors required - Very long time required to collect signal..

25 IceCube neutrino telescope